How are you taking part in this consultation?

You will not be able to change how you comment later.

You must be signed in to answer questions

    The content on this page is not current guidance and is only for the purposes of the consultation process.

    Interventional procedure overview of supercapsular percutaneously assisted total hip arthroplasty for osteoarthritis

    Closed for comments This consultation ended on at   Request commenting lead permission

    Summary of key evidence on supercapsular percutaneously assisted total hip arthroplasty for osteoarthritis

    Study 1 Xie J (2017)

    Study details

    Study type

    Randomised controlled trial

    Country

    China (single centre)

    Recruitment period

    2015 to 2016

    Study population and number

    n=92 (SuperPath, n=46; conventional posterior, n=46)

    Patients with unilateral primary hip osteoarthritis

    Age and sex

    SuperPath group: mean 66.6 years; 74% (34/46) male; BMI, mean 23.62±1.63 kg/m2

    Conventional posterior group: mean 64.5 years; 59% (27/46) male; BMI, mean 24.06±2.72 kg/m2

    Patient selection criteria

    Inclusion criteria: patients with unilateral primary hip osteoarthritis.

    Exclusion criteria: femoral neck fracture, severe acetabular defect, metastatic disease, and overweight patients with a body mass index over 40.

    Technique

    The SuperPath approach (MicroPort Orthopedics Inc., Arlington, TN, USA) was done in 1 group and the conventional posterior approach (Moore approach) in another group. All patients were implanted with the same cementless THA implants (such as acetabular component, acetabular liner, femoral component and femoral head).

    Follow-up

    1 year

    Conflict of interest/source of funding

    Conflict of interest: none

    Funding: This study was supported by the Health Science and Technology Special Projects Foundation of Zhenjiang, Jiangsu Province (SHW2016005).

    Analysis

    Follow-up issues: Patients were followed up in the same rehabilitation unit at 1 week, 1 month, 3 months and 1 year after operation.

    Study design issues: This prospective, randomised controlled trial compared the SuperPath approach with the conventional posterior approach, in terms of the early outcomes and radiological results. This study was carried out according to the 'CONSORT statement' guidelines for randomised controlled trials. All surgeries were done by one senior orthopaedic chief surgeon.

    Functional outcomes were evaluated using the following measures: HHS, Barthel index, VAS for pain level, TUG and TSC. Other results included incision length, blood loss, skin-to-skin operative time, length of stay, and complication rates. All analyses were based on the intention-to-treat group and per-protocol group. And the result of the intention-to-treat analysis would be compared with that of the per-protocol analysis to check whether the results were consistent.

    Study population issues: At baseline, there was no statistically significant difference in terms of age, sex, BMI, VAS, HHS and Barthel index.

    Other issues: There were several limitations, including small sample size, short-term follow up, patients not being blinded for the approach chose. There was no information relating to the comparison of the results based on intention-to-treat analysis with that of the per-protocol analysis for consistency as planned.

    Key efficacy findings

    Number of patients analysed: 92

    Perioperative outcomes

    SuperPath (n=46)

    Conventional posterior (n=46)

    P value

    Operation time, minutes

    103.6±11.8

    106.5±16.5

    0.53

    Incision length, cm

    7.4±1.06

    14.5±2.38

    0.000

    Blood loss, ml

    303.6±106.3

    326.4±127.2

    0.11

    Transfusion rate

    4.3% (n=2)

    11% (n=5)

    0.24

    Length of stay, days

    8.3±3.6

    11.4±2.4

    0.000

    All patients were assessed according to their ability to walk weight bearing as tolerated on the first postoperative day. All the patients in the SuperPath group mobilised without restriction while the conventional posterior group mobilised with hip precautions for 4 weeks.

    Pre- and Post-operative outcomes

    Follow-up time

    SuperPath

    Conventional posterior

    P value

    VAS

    Baseline

    7.62±1.63

    7.06±1.72

    0.53

    1 week

    4.86±0.83

    6.53±0.52

    0.000

    1 month

    2.6±0.82

    3.4±0.63

    0.009

    3 months

    1.4±0.63

    1.87±0.74

    0.048

    1 year

    0.87±0.51

    0.97±0.35

    0.16

    TUG, minutes

    1 week

    2.06±1.43

    3.2±1.47

    0.002

    1 month

    1.33±0.36

    2.57±0.59

    0.016

    3 months

    0.92±0.10

    1.2±0.23

    0.036

    1 year

    0.52±0.12

    0.58±0.09

    0.70

    TSC, minutes

    1 week

    5.34±1.85

    7.2±2.04

    0.000

    1 month

    2.56±0.78

    3.47±0.83

    0.022

    3 months

    1.96±0.69

    2.21±0.55

    0.041

    1 year

    1.06±0.13

    1.09±0.19

    0.55

    HHS

    Baseline

    28.9±11.32

    29.3±17.40

    0.40

    1 week

    73.8±3.89

    69±4.81

    0.009

    1 month

    81.4±3.18

    76.8±2.93

    0.000

    3 months

    87.6±1.76

    80.1±4.49

    0.000

    1 year

    92.3±1.62

    91.6±2.41

    0.26

    Barthel index

    Baseline

    68.9±8.35

    65.3±7.64

    0.13

    1 week

    70.67±9.47

    64.46±7.70

    0.000

    1 month

    79.6±10.01

    74.26±5.76

    0.017

    3 months

    90.26±7.12

    83.07±8.62

    0.01

    1 year

    94.33±6.90

    93.60±8.74

    0.334

    Radiological evaluation of the position of the implants

    SuperPath

    Conventional posterior

    P value

    Cup abduction angle, o

    43.6±6.8

    44.5±6.5

    0.41

    Cup anteversion angle, o

    17.4±1.6

    18.5±1.8

    0.23

    Stem alignment neutral, o

    43

    44

    0.21

    Varus, o

    2

    1

    0.62

    Valgus, o

    1

    1

    -

    If the angle was under 1° valgus or varus, it was considered as good.

    Key safety findings

    None of the patients had fractures, postoperative infection, nerve damage or heterotopic ossification. No significant postoperative complications were reported in either group.

    SuperPath group:

    • Dislocation after 1 week: n=1

    Conventional posterior group:

    • Deep venous thrombosis: n=1

    • Dislocation after 2 weeks: n=2

    At the 1-year follow-up, no prosthesis was loosened or subsided.

    Study 2 Meng WK (2021)

    Study details

    Study type

    Randomised controlled trial

    Country

    China

    Recruitment period

    2017 to 2018

    Study population and number

    n=40 (SuperPath, n=20; posterolateral THA, n=20)

    Patients with unilateral end-stage primary hip osteoarthritis

    Age and sex

    SuperPath group: mean 64.55 years; 40% (8/20) male; BMI, mean 23.26±2.55 kg/m2

    Posterolateral group: mean 65.25 years; 45% (9/20) male; BMI, mean 22.82±2.61 kg/m2

    Patient selection criteria

    Inclusion criteria: patients had unilateral end-stage primary hip osteoarthritis, provided signed consent for implanting and agreed to complete the scheduled postoperative 12-month follow-up.

    Exclusion criteria: patients had non-inflammatory degenerative joint diseases (e.g., osteonecrosis, bilateral osteoarthritis, and post-traumatic arthritis), inflammatory joint diseases (e.g., reactive arthritis, ankylosing spondylitis, rheumatoid arthritis, and gout), inadequate neuromuscular status (e.g., previous paralysis and inadequate abductor strength), and overt infections or distant foci of infections.

    Technique

    SuperPath and mini-incision posterolateral THA were done with specific prostheses (SuperPath group: Microport Orthopaedics, Arlington, TN, USA; posterolateral group: DePuy Synthes, Warsaw, IN, USA).

    Standardised postoperative care was provided, including infection prophylaxis, venous thromboembolism prevention, nausea and vomiting management, wound care and functional rehabilitation.

    Follow-up

    12 months

    Conflict of interest/source of funding

    Funding: Research funding and support was provided by the National Health and Family Planning Commission of the People's Republic of China (No. 201302007) and the Sichuan Science and Technology Support Project (No. 2018SZ0145 and No. 2018SZYZF000). WKM received financial support from the China Scholarship Council.

    Conflict of interest:

    • LG: a section editor of Annals of Translational Medicine.

    • Other authors: no conflicts of interest.

    Analysis

    Follow-up issues: Patients were followed up at postoperative days 1, 3 and 14, and then at 3, 6, and 12 months after surgery. No patients were lost to follow up or stopped the intervention.

    Study design issues: This prospective, double-blind, randomised controlled trial compared the short-term outcomes between SuperPath and mini-incision posterolateral THA for patients with unilateral end-stage primary osteoarthritis. The hypothesis was that SuperPath would yield superior outcomes for osteoarthritis patients compared to posterolateral THA, with better perioperative status and improved postoperative function. This study was conducted according to the principles of the Declaration of Helsinki and presented in accordance with the CONSORT reporting checklist.

    All surgical procedures were completed by the same team, led by a senior surgeon specialising in lower limb reconstruction, with over 15 years' experience doing primary and revision THA (over 250 cases annually). To minimise the influence of a learning curve, the senior surgeon had done more than 50 SuperPath cases prior to the present trial. Patients were randomised to each group, using a shuffled deck of cards (even: SuperPath, odd: posterolateral).

    Postoperative rehabilitation: Both groups had an identical rehabilitation program, which was delivered by an experienced physical therapist who received extensive training in managing postoperative hip conditions before this study. The physical therapist was blinded to the patient allocation. Briefly, immediate hip flexion, pneumatic compression with foot pumps, and deep breathing exercises were emphasized to minimise thromboembolic and pulmonary complications. After obtaining written approval from the physical therapist, patients began indoor walking independently with a tolerated weight bearing. Patients were educated in self-care and home-based rehabilitation before discharge. They were instructed to walk daily and to gradually increase their walking distance toward a goal of 2 km/day.

    Study population issues: At baseline, there was no statistically significantly difference between the 2 groups in terms of age, sex, BMI, comorbidities and American Society of Anaesthesiologist grade.

    Other issues: The sample size was relatively limited without a power analysis done in the research planning phase, and the postoperative follow-up was short. The extent of muscle damage was only assessed with serum markers within 2 weeks postoperatively, while no radiographic analyses were done to confirm perioperative alterations of these serum markers.

    Key efficacy findings

    Number of patients analysed: 40

    All patients were discharged at postoperative day 3 and allowed to walk with a cane.

    Perioperative data, mean (SD)

    SuperPath (n=20)

    Posterolateral (n=20)

    P value

    Incision length, cm

    7.83 (1.12)

    12.45 (1.71)

    <0.001

    Operative time, minutes

    102.72 (13.55)

    66.22 (11.59)

    <0.001

    Blood loss, mL

    1,007.38 (174.22)

    844.55 (161.16)

    0.005

    Length of stay, days

    3.00 (0.00)

    2.72 (0.57)

    0.161

    Transfusion rate

    0

    0

    n/a

    Readmission within 12 months postoperatively, n (%)

    0

    0

    n/a

    Reoperation with 12 months postoperatively, n (%)

    0

    0

    n/a

    Radiological evaluation of acetabular cup positioning on postoperative day 1, mean (SD)

    Variable

    SuperPath (n=20)

    Posterolateral (n=20)

    P value

    Abduction angle, o

    36.94 (6.37)

    42.66 (3.58)

    0.004

    Anteversion angle, o

    13.94 (4.73)

    15.11 (4.06)

    0.501

    Preoperative and postoperative ROM (o), pain VAS and HHS within 12 months postoperatively, mean (SD)

    Variable

    Time point

    SuperPath (n=20)

    Posterolateral (n=20)

    P value

    Flexion

    Preoperative

    90.33 (14.11)

    89.61 (11.81)

    0.815

    Postoperative day 1

    107.66 (7.87)

    114.44 (4.81)

    0.004

    Postoperative day 3

    109.83 (6.54)

    116.11 (4.39)

    0.002

    Postoperative day 14

    111.66 (6.18)

    118.88 (3.23)

    <0.001

    Postoperative 3 months

    119.72 (5.80)

    121.22 (3.65)

    0.501

    Postoperative 6 months

    121.44 (4.52)

    123.05 (5.97)

    0.628

    Postoperative 12 months

    124.72 (5.27)

    124.16 (7.12)

    0.481

    Abduction

    Preoperative

    21.94 (10.86)

    23.05 (9.09)

    0.521

    Postoperative day 1

    28.61 (5.89)

    29.44 (5.65)

    0.584

    Postoperative day 3

    28.88 (5.82)

    30.55 (5.65)

    0.323

    Postoperative day 14

    31.38 (4.79)

    32.77 (4.27)

    0.339

    Postoperative 3 months

    34.44 (4.16)

    35.27 (3.19)

    0.521

    Postoperative 6 months

    36.11 (4.39)

    36.66 (3.42)

    0.767

    Postoperative 12 months

    38.61 (4.13)

    38.33 (2.97)

    0.815

    Adduction

    Preoperative

    16.75 (3.95)

    14.75 (4.11)

    0.521

    Postoperative day 1

    15.75 (0.96)

    15.50 (1.00)

    0.767

    Postoperative day 3

    18.25 (1.25)

    18.75 (1.50)

    0.628

    Postoperative day 14

    21.25 (2.50)

    22.25 (0.96)

    0.938

    Postoperative 3 months

    23.50 (2.38)

    24.00 (1.41)

    0.888

    Postoperative 6 months

    26.00 (1.41)

    24.50 (3.70)

    0.424

    Postoperative 12 months

    26.75 (2.36)

    27.25 (4.35)

    0.791

    External rotation

    Preoperative

    21.00 (4.55)

    20.75 (3.10)

    0.815

    Postoperative day 1

    21.00 (7.26)

    22.25 (3.30)

    0.791

    Postoperative day 3

    23.50 (5.97)

    24.25 (2.99)

    0.888

    Postoperative day 14

    27.25 (3.20)

    26.75 (2.36)

    0.988

    Postoperative 3 months

    30.75 (2.63)

    30.50 (2.38)

    0.767

    Postoperative 6 months

    33.25 (0.96)

    34.50 (3.11)

    0.424

    Postoperative 12 months

    37.75 (2.63)

    36.25 (4.79)

    0.696

    Pain VAA

    Preoperative

    7.61 (0.77)

    7.38 (0.60)

    0.443

    Postoperative day 1

    7.38 (0.77)

    6.94 (0.72)

    0.097

    Postoperative day 3

    7.05 (0.72)

    6.55 (0.70)

    0.041

    Postoperative day 14

    5.00 (1.02)

    4.44 (0.92)

    0.097

    Postoperative 3 months

    1.77 (0.80)

    1.55 (0.85)

    0.372

    Postoperative 6 months

    0.66 (0.68)

    0.72 (0.57)

    0.743

    Postoperative 12 months

    0.05 (0.23)

    0.11 (0.32)

    0.791

    HHS

    Preoperative

    45.61 (12.77)

    43.44 (12.91)

    0.521

    Postoperative day 1

    62.50 (10.07)

    60.11 (6.46)

    0.443

    Postoperative day 3

    66.44 (9.03)

    63.50 (7.17)

    0.293

    Postoperative day 14

    72.27 (8.33)

    70.66 (6.22)

    0.339

    Postoperative 3 months

    82.44 (3.51)

    82.38 (2.68)

    0.815

    Postoperative 6 months

    87.77 (3.47)

    87.55 (3.56)

    0.839

    Postoperative 12 months

    92.16 (2.76)

    92.66 (2.80)

    0.988

    Changes in pain VAS and HHS within 12 months after operation

    Comparisons between assessment time points

    VAS

    HHS

    SuperPath

    Posterolateral

    SuperPath

    Posterolateral

    Preoperative compared with postoperative day 1

    0.974

    0.477

    <0.001

    <0.001

    Preoperative compared with postoperative day 3

    0.295

    0.009

    <0.001

    <0.001

    Preoperative compared with postoperative day 14

    <0.001

    <0.001

    <0.001

    <0.001

    Preoperative compared with postoperative 3 months

    <0.001

    <0.001

    <0.001

    <0.001

    Preoperative compared with postoperative 6 months

    <0.001

    <0.001

    <0.001

    <0.001

    Preoperative compared with postoperative 12 months

    <0.001

    <0.001

    <0.001

    <0.001

    Postoperative day 1 compared with postoperative day 3

    0.837

    0.636

    0.757

    0.751

    Postoperative day 1 compared with postoperative day 14

    <0.001

    <0.001

    0.007

    <0.001

    Postoperative day 1 compared with postoperative 3 months

    <0.001

    <0.001

    <0.001

    <0.001

    Postoperative day 1 compared with postoperative 6 months

    <0.001

    <0.001

    <0.001

    <0.001

    Postoperative day 1 compared with postoperative 12 months

    <0.001

    <0.001

    <0.001

    <0.001

    Postoperative day 3 compared with postoperative day 14

    <0.001

    <0.001

    0.310

    0.033

    Postoperative day 3 compared with postoperative 3 months

    <0.001

    <0.001

    <0.001

    <0.001

    Postoperative day 3 compared with postoperative 6 months

    <0.001

    <0.001

    <0.001

    <0.001

    Postoperative day 3 compared with postoperative 12 months

    <0.001

    <0.001

    <0.001

    <0.001

    Postoperative day 14 compared with postoperative 3 months

    <0.001

    <0.001

    0.004

    <0.001

    Postoperative day 14 compared with postoperative 6 months

    <0.001

    <0.001

    <0.001

    <0.001

    Postoperative day 14 compared with postoperative 12 months

    <0.001

    <0.001

    <0.001

    <0.001

    Postoperative 3 months compared with postoperative 6 months

    <0.001

    0.009

    0.420

    0.267

    Postoperative 3 months compared with postoperative 12 months

    0.001

    <0.001

    0.004

    <0.001

    Postoperative 6 months compared with postoperative 12 months

    0.193

    0.127

    0.542

    0.280

    Key safety findings

    No postoperative complications in either group.

    Study 3 Korytkin AA (2021)

    Study details

    Study type

    Randomised controlled trial

    Country

    Russia (single centre)

    Recruitment period

    2018 to 2019

    Study population and number

    n=44 (SuperPath, n=20; mini posterior, n=24)

    Patient with non-inflammatory degenerative joint disease

    Age and sex

    SuperPath group: mean 56.75 years; 50% (10/20) male; BMI, mean 28.2 kg/m2

    Mini posterior group: mean 56.96 years; 46% (11/24) male; BMI, mean 29.04 kg/m2

    Patient selection criteria

    Inclusion criteria: patients had unilateral hip disease, were included if they were more than 20 years of age, with non-inflammatory degenerative joint disease, if they were able and available to attend follow up and were willing to sign the informed consent form.

    Exclusion criteria: BMI more than 40 kg/m2, rapid disease progression and neuromuscular diseases.

    Technique

    Cementless acetabular component Dynasty® PC Shell and femoral component Profemur Z classic femoral stem with a cobalt chrome femoral head on Ultra high molecular weight Dynasty A-class poly liner (MicroPort Orthopedics, Inc. Arlington, TN, USA) were used. A 32-mm diameter head was used in 19 cases and 28-mm in 1 case of the SuperPath group, whereas in the mini posterior group, the 32-mm head was used in 23 cases and the 28-mm in 1 case.

    Patients were weight-bearing as tolerated on the day of surgery regardless of approach. Patients in the mini posterior group were given standard postoperative precautions to prevent dislocation, whereas the SuperPath group was not given any restrictions.

    Follow-up

    6 weeks

    Conflict of interest/source of funding

    Funding: The study was supported by MicroPort Orthopedics Inc. (Grant Number 04.02 T003).

    Conflict of interest: none.

    Analysis

    Follow-up issues: Forty-nine patients met the inclusion criteria and had surgery using one of the 2 approaches (22 in the SuperPath group and 27 in the mini posterior group). In the SuperPath group, 2 patients were lost to follow up. In the MPA group, 3 patients were not available: 2 patients chose not to participate, 1 patient was still using a walking aid at 6 weeks follow up.

    Study design issues: This prospective, randomised clinical trial tested the hypothesis that patients having THA using the SuperPath technique would achieve improved gait parameters with better functional and clinical results than patients operated on using the mini posterior approach. This trial also evaluated patients' hip kinetics and kinematic changes in walking performance. Two unbiased biostatisticians, blinded to patient attribution and outcome, did the statistical work. Gait analysis was done by an independent researcher with expertise in such an analysis, who was blinded to patients' allocation, at the clinic biomechanical laboratory.

    Based on the time to stopping use of a walking aid using mini posterior approach as 28.5 days, the total sample size of 52 patients (26 patients per group) with the probability of alpha errors at 0.05, with a power of 0.80 is sufficient to detect differences between groups. Patients who met the inclusions criteria were randomly assigned to either the mini posterior or SuperPath group according to a computed randomisation list, with numbered and sealed envelopes opened before the operation.

    All procedures were done by a fellowship-trained surgeon. Early postoperative rehabilitation was the same for both groups and was done by the same physiotherapy team at the same institution and started the first day after surgery. Upon discharge, patients were advised to resume activities as they could tolerate.

    Study population issues: At baseline, there was no statistically significantly difference between the 2 groups in terms of age, sex, BMI, disease duration, and VAS, HHS and HOOS scores.

    Limitations: This study had a short-term follow up, patients were not blinded to the approach, and gain parameters were collected in the sagittal plane only (frontal and transversal planes were not included for comprehensive analysis).

    Key efficacy findings

    Number of patients analysed: 44

    Incision length: range 7 to 11 cm.

    Surgical outcomes, mean±SD (range)

    Variable

    SuperPath (n=20)

    Mini posterior (n=24)

    P value

    Operation time, minutes

    63.2±9.87 (50 to 80)

    61.7±14.1 (40 to 90)

    0.33

    Estimated blood loss, ml

    177.5±54.95 (100 to 300)

    204.16±83.29 (50 to 450)

    0.1

    Haemoglobin (g/ml)

    Preoperative

    136.3±15.19 (110 to 166)

    139.29±18.93 (106 to 173)

    0.56

    Postoperative day 5

    110.15±14 (81 to 138)

    117±18.85 (90 to 154)

    0.17

    Haematocrit, %

    Preoperative

    42±3.87 (35 to 52.6)

    41.19±6.13 (28.2 to 52.3)

    0.56

    Postoperative day 5

    32.89±4.51 (24.1 to 43.6)

    35.2±5.91 (27 to 46.7)

    0.14

    Hospital stay, days

    8.85±1.66 (5 to 13)

    8.66±1.63 (6 to 13)

    0.35

    Stay after operation, days

    6.2±1.28 (3 to 8)

    6.1±1.55 (3 to 11)

    0.39

    Radiological evaluation of implant position

    Variable

    SuperPath (n=20)

    Mini posterior (n=24)

    P value

    Cup anteversion, mean (range)

    18o (range 16o to 21o)

    19o (range 16o to 24o)

    All p>0.05

    Cup inclination, mean (range)

    43o (range 32o to 48o)

    44o (range 31o to 49o)

    Stem alignment

    Neutral

    100%

    96%

    >2o in varus

    4%

    Clinical and functional outcomes, mean±SD

    Variable

    Follow-up time

    SuperPath

    Mini posterior

    P value

    VAS

    Preoperatively

    5.7±2.03

    5.4±1.81

    0.63

    6 weeks

    0.85±0.58

    1.87±1.2

    0.001

    HHS

    Preoperatively

    45.6±11.3

    46±11

    0.79

    6 weeks

    78.6±9.18

    68.8±15.1

    0.01

    HOOS

    Preoperatively

    40.1±10.3

    41.3±15.7

    0.75

    Symptoms

    44.5±11.2

    46.8±16.6

    0.57

    Pain

    46±11.3

    43.3±18.3

    0.55

    FDL (function – daily living)

    43.1±12.1

    44.6±18.8

    0.06

    FSR (function – sport and recreational activities)

    26.8±21.9

    32±25.7

    0.47

    Quality of life

    20±12.4

    25±19.7

    0.31

    HOOS

    6 weeks

    81.3±10.9

    72.47±13.5

    0.01

    Symptoms

    86.7±10.3

    79.8±12.2

    0.04

    Pain

    89.1±9.7

    80.4±15.3

    0.02

    FDL (function – daily living)

    80.4±11.9

    71.7±15.3

    0.04

    FSR (function – sport and recreational activities)

    80.3±21.7

    74±27.3

    0.39

    Quality of life

    60.3±17.9

    45.05±23.6

    0.01

    Overall, all the patients were satisfied with the results.

    Spatio-temporal parameters of gait

    Parameter

    SuperPath

    Mini posterior

    P value

    Gait velocity, km/h

    Preoperatively

    3.02±0.72

    2.92±0.85

    0.66

    6 weeks

    3.00±0.92

    2.69±1.00

    0.28

    Stance phase, %

    Preoperatively

    65.13±5.25

    65.63±4.27

    0.73

    6 weeks

    66.01±4.20

    68.36±6.17

    0.14

    Swing phase, %

    Preoperatively

    34.01±5.78

    34.37±4.27

    0.82

    6 weeks

    33.99±4.20

    31.64±6.17

    0.14

    Double step length

    Preoperatively

    1.00±0.19

    1.01±0.22

    0.84

    6 weeks

    1.03±0.22

    0.94±0.26

    0.26

    ROM hip

    Preoperatively

    25.66±6.74

    27.26±8.01

    0.47

    6 weeks

    26.29±5.46

    25.79±6.20

    0.77

    ROM knee

    Preoperatively

    51.95±8.66

    50.88±9.21

    0.69

    6 weeks

    51.59±9.70

    48.58±10.28

    0.32

    ROM ankle

    Preoperatively

    24.99±6.70

    24.82±4.08

    0.92

    6 weeks

    26.07±6.22

    27.12±4.83

    0.53

    Comparison of the mean differences in gait velocity between preoperative and the 6 weeks postoperative outcomes, revealed improvement in the SuperPath group over the mini posterior group (p=0.06).

    For kinematics, flexion/extension ROM, hip joint excursion statistically significantly improved in the SuperPath group, compared to the mini posterior group (p=0.04). Knee joint excursion consequently improved for the SuperPath group (p=0.31).

    Stance phase before and after the operation

    Parameter

    SuperPath

    Mini posterior

    Involved side

    Contralateral side

    P value

    Involved side

    Contralateral side

    P value

    Preoperation

    65.13%±5.25%

    69.36%±4.46%

    0.009

    65.63%±4.27%

    68.89%±3.93%

    0.01

    6 weeks after the operation

    66.01%±4.2%

    68.47%±5.35%

    68.36%±6.17%

    70.95%±8.35

    Key safety findings

    No major complications were seen in either group.

    Study 4 Rasuli KJ (2015)

    Study details

    Study type

    Non-randomised comparative study

    Country

    Canada (single centre)

    Recruitment period

    SuperPath: 2013 to 2014

    PATH: 2009 to 2011

    Study population and number

    n=99 (SuperPath, n=50; PATH, n=49)

    Patients with degenerative hip arthritis

    Age and sex

    SuperPath group: mean 68.1 years; 38% male; BMI, mean 29.4 kg/m2

    PATH group: mean 68.2 years; 47% male; BMI, mean 29.6 kg/m2

    Patient selection criteria

    Inclusion criteria: patients had a diagnosis of degenerative hip arthritis, failed nonoperative therapy, and were candidates for THA.

    Exclusion criteria: patients presented with a femoral neck fracture, severe acetabular defect likely to need grafting or augmentation, metastatic disease, or had simultaneous bilateral procedures.

    Technique

    SuperPath and PATH techniques were used.

    Follow-up

    SuperPath: mean 7.9 months

    PATH: mean 24.7 months

    Conflict of interest/source of funding

    WG: Active consultant for Microport, receiving fees for technique training.

    RKJ: no conflicts of interest to declare

    Analysis

    Study design issues: This study assessed the early outcomes of 2 micro-posterior approaches (SuperPath and PATH) when done by a non-developer surgeon. The surgeon had 4 years of experience doing primary THA exclusively through a Hardinge approach and had experience with the posterior approach for trauma and revision THA. He does about 250 joint replacements per year, of which 50% are THA. This study also evaluated the learning curve associated with the SuperPath and PATH approaches to assess whether the outcomes reported in the literature are likely to be reproducible by surgeons incorporating these innovative techniques into their own practice.

    Clinical outcomes included operative time and length of stay, postoperative blood transfusion, acetabular cup abduction and anteversion (evaluated using the first postoperative anteroposterior pelvis and a modified protractor).

    Study population issues: No significant statistical difference was identified between the 2 groups in terms of age, gender, BMI or preoperative haemoglobin.

    Other issues: This study did not compare the outcomes of the SuperPath approach with more traditional approaches used in THA. Other limitations of this study included small sample size, lack of long-term follow up and lack of functional results.

    Key efficacy findings

    Number of patients analysed: 99

    Comparison of clinical outcomes between groups

    Comparison items

    SuperPath

    PATH

    P value

    Mean operation time, minutes

    114.5±17.5

    101.7±18.3

    0.0002

    Mean length of stay, days

    2.2±0.9

    3.0±0.8

    <0.0001

    Discharged home by percentage of patients discharged by postoperative day 1, %

    20

    0

    Discharged home by percentage of patients discharged by postoperative day 2, %

    64

    27

    DC by percentage of patients discharged by postoperative day 3, %

    96

    78

    Discharged directly home, %

    90

    81.6

    >0.05

    Short-term inpatient rehabilitation, %

    2

    14.3

    Planned convalescence, %

    8

    4.1

    Patients having tranexamic acid, %

    92

    40.8

    >0.05

    Postoperative blood transfusion, %

    4.0

    6.1

    >0.05

    Radiographic outcomes

    Mean acetabular cup anteversion, o

    23.5±8.2

    13.1±7.1

    <0.0001

    Mena acetabular cup abduction, o

    39.0±8.4

    42.9±7.6

    <0.05

    For operation time, the correlation coefficient for the SuperPath cohort was significant (−0.467, p<0.001) but not for the PATH cohort (−0.0246, p=0.088).

    Mean length of stay in short-term rehabilitation was calculated for the PATH (10.6±3.1) group but not for the SuperPath approach as only 1 patient attended short-term rehabilitation (7 days) in the SuperPath group.

    Key safety findings

    Intraoperative and postoperative complications

    Approaches

    Overall complications

    Intraoperative complications

    Postoperative complications

    SuperPath

    4.0%

    1 femoral calcar fracture (case 5): extension of the skin incision, piriformis release and cerclage wiring, weight-bearing as tolerated

    1 transfusion reaction (case 21): recovered with supportive care

    PATH

    4.1%

    1 femoral calcar fracture (case 10): extension of the skin incision and cerclage wiring, weight-bearing as tolerated

    1 dislocation at 6 weeks (case 26): modular neck revision and soft tissue capsular repair

    Case 21 returned to hospital following discharge complaining of fatigue. The patient was found to be anaemic (haemoglobin 74 g/L) and had a blood transfusion. Subsequently, this patient developed an acute haemolytic transfusion reaction, but recovered with supportive measures.

    No superficial or deep infections were found in the SuperPath or PATH group.

    Study 5 Mas Martinez J (2019)

    Study details

    Study type

    Non-randomised comparative study

    Country

    Spain (single centre)

    Recruitment period

    2016 to 2017

    Study population and number

    n=90 (SuperPath, n=30; posterior, n=60)

    patients with hip arthrosis

    Age and sex

    SuperPath group: mean 56 years; 66.7% (20/30) male; BMI, mean 27.5 kg/m2

    Posterior group: mean 60 years; 66.7% (40/60) male: BMI, mean 27.9 kg/m2

    Patient selection criteria

    Inclusion criteria: patients with a diagnosis of hip arthrosis and indication for cementless hip replacement surgery.

    Exclusion criteria: patients with femoral or acetabular defects, acetabular protrusion, femoral fracture, or neurological condition with impaired gait.

    Technique

    THA using the SuperPath or posterior approach was done.

    SuperPath group: Profemur L stem and Procotyle® cup (MicroPort Orthopedics Inc., Arlington, TN, USA) were used. The bearing surface used was the ceramic-ceramic in 5 patients, ceramic-polyethylene in 17 patients and the metal-polyethylene in 8 patients. The size of the femoral head was 28 mm in 8 patients, 32 mm in 15 patients and 36 mm in 7 patients.

    Posterior group: stem Accolade and Trident® cup (Stryker, Kalamazoo, MI, USA) were used. The bearing surface used was the ceramic-ceramic in 5 patients, ceramic-polyethylene in 44 patients and the metal-polyethylene in 11 patients. The size of the femoral head was 28 mm in 10 patients, 32 mm in 28 patients and 36 mm in 22 patients.

    No postoperative drains were used.

    Follow-up

    1 year

    Conflict of interest/source of funding

    None

    Analysis

    Follow-up issues: Patients were assessed at 3 months, 6 months and 1 year after operation. No patients were lost to follow up.

    Study design issues: This prospective, observational cohort study (cohort-paired) determined the short-term results of patients that had a THA intervention using the SuperPath approach, and compared the results with patients operated for THA using conventional posterior approach. The hypothesis was that the SuperPath approach would make it possible to obtain results similar to those of the posterior approach.

    Outcomes included hip function outcomes (measured using HHS, Merle d'Aubigné Hip Score, WOMAC for pain and for function, SF-12 physical and mental scales, HOS-AVD and iHOT-12 scales), pre- and post-operative variables and radiological evaluation.

    After the operation, walking with crutches or a walker was authorised after assessing the radiological control and postoperative laboratory results. The patient was told not to do any activities that increased pain in the operated hip. The suture was removed after 2 postoperative weeks.

    Study population issues: At baseline, there was no statistically significant difference between the 2 groups in terms of age, sex, BMI, ASA, preoperative haemoglobin and haematocrit.

    Study limitations: Different stem-stem models were used in the 2 groups. The surgeon-dependent distribution of patients into the SuperPath or posterior approaches.

    Key efficacy findings

    Number of patients analysed: 90

    Pre- and post-operative variables

    Variables

    SuperPath

    Posterior

    P value

    Mean operation time, minutes

    69.5±7.1

    56.1±5.2

    0.001

    Mean pre-operative haemoglobin, g/dl

    14.8

    14.6

    0.61

    Mean postoperative haemoglobin

    11.2±1.3

    12.5±1.5

    0.07

    Mean haemoglobin decrease

    3.4±1.0

    2.5±0.8

    0.04

    Mean pre-operative haematocrit

    42.1

    42.9

    0.83

    Mean postoperative haematocrit

    32.1±3.3

    35.6±4.8

    0.03

    Mean haematocrit decrease

    10.3±3.2

    7.7±3.0

    0.04

    Mean blood loss, ml

    977.85±285.1

    752.46±299.3

    0.03

    Mean hospital stay, days

    2.2

    2.4

    0.23

    None of the patients needed autologous blood transfusion.

    Clinical assessment results

    Outcomes, mean±SD

    SuperPath

    Posterior

    P value

    Preoperative

    HHS

    48.8±7.1

    50.0±14.5

    0.75

    Merle d'Aubigné hip score

    5.1±1.8

    5.7±1.9

    0.38

    WOMAC pain

    38.2±14.6

    41.3±12.9

    0.20

    WOMAC function

    31.8±13.8

    39.5±14.7

    0.08

    SF-12 physical

    39.8±12.3

    41.7±12.6

    0.27

    SF-12 mental

    46.1±13.7

    47.6±14.7

    0.29

    HOS-AVD

    38.6±13.5

    39.2±13.1

    0.90

    iHOT-12

    15.2±15.1

    22.2±18.7

    0.27

    3 Months

    HHS

    91.6±8.8

    93.7±5.4

    0.51

    Merle d'Aubigné hip score

    10.7±1.4

    11.0±1.3

    0.55

    WOMAC pain

    87.2±14.1

    85.8±16.1

    0.49

    WOMAC function

    85.4±12.6

    79.7±14.6

    0.24

    SF-12 physical

    82.4±13.7

    85.5±13.5

    0.95

    SF-12 mental

    82.7±12.4

    81.8±14.2

    0.92

    HOS-AVD

    84.2±14.7

    75.1±18.8

    0.15

    iHOT-12

    78.2±15.6

    63.5±22.8

    0.04

    6 months

    HHS

    90.2±12.8

    92.4±9.3

    0.21

    Merle d'Aubigné hip score

    10.1±2.1

    10.6±1.4

    0.41

    WOMAC pain

    96.2±12.5

    92.7±12.9

    0.57

    WOMAC function

    92.9±12.9

    89.6±14.6

    0.28

    SF-12 physical

    85.5±13.6

    86.3±13.0

    0.50

    SF-12 mental

    84.7±15.4

    82.6±14.4

    0.57

    HOS-AVD

    82.3±17.7

    80.5±19.7

    0.77

    iHOT-12

    76.0±24.8

    70.6±22.5

    0.74

    12 months

    HHS

    98.2±2.0

    96.2±5.6

    0.24

    Merle d'Aubigné hip score

    11.8±0.4

    11.3±0.8

    0.14

    WOMAC pain

    97.0±11.6

    91.2±12.8

    0.42

    WOMAC function

    93.0±13.6

    91.6±13.4

    0.44

    SF-12 physical

    88.6±10.5

    79.0±13.5

    0.04

    SF-12 mental

    85.6±12.0

    76.1±15.3

    0.02

    HOS-AVD

    89.8±13.1

    84.2±18.0

    0.42

    iHOT-12

    78.5±18.3

    76.8±14.9

    0.53

    The hip function surveys showed statistically significant increases between the preoperative values and those at 12 months in both groups (p<0.001).

    Radiological evaluation at 3 months

    Mean angle of acetabular inclination: SuperPath 47.6o compared with posterior 45.9o, p=0.41

    All the femoral stems were implanted in neutral position. There were no recorded cases of mobilisation of prosthetic components.

    Key safety findings

    SuperPath:

    • Intraoperative acetabular fracture: n=1

    The patient having treatment with teriparatide for osteoporosis presented fracture of the acetabular background during the impaction of the cup component. The external rotators were removed and the approach was converted to a conventional posterior approach. Given that osseous acetabular circumferential stability existed, a cemented stem was implanted. Evolution at 12 months follow up was satisfactory, with a Harris Scale score of 82 points and Merle scale score of 10 points.

    • Progressive pain in the buttock on the affected side at 6 months: n=1

    Complete radiolucency of the stem without implant mobilisation was detected in the radiological control, and the patient was pending surgical revision.

    Posterior:

    • Hospital readmission at 14 days postoperation for periprosthetic infection: n=1

    This event needed debridement and replacement of mobile components. Evolution was good at 1-year follow up, with a Harris Scale score of 84 points and a Merle scale score of 10 points.

    There were no cases of prosthetic dislocations or thromboembolic complications during follow-up in either cohort.

    Study 6 Qultmann H (2019)

    Study details

    Study type

    Case series

    Country

    Germany (single centre)

    Recruitment period

    2016 to 2017

    Study population and number

    n=150

    Patients with osteoarthritis of the hip

    Age and sex

    Mean 69 years; 35% (52/150) male; BMI, mean 27 kg/m2

    Patient selection criteria

    Not reported

    Technique

    Cementless THA using the SuperPath approach.

    Follow-up

    16 months

    Conflict of interest/source of funding

    HQ: consultant for MicroPort Orthopedics for surgical observation services

    Analysis

    Study design issues: This paper described the SuperPath technique and reported preliminary results. For postoperative management, full weight bearing was allowed as tolerated by pain and there were no restrictions of postoperative movement.

    Study population issues: Limited baseline data were presented.

    Key efficacy findings

    Number of patients analysed: 150

    Operation time: 81 minutes (range 58 to 121 minutes)

    Inclination angle: 39.3o (range 28o to 50o)

    Leg length difference: 5 mm or less

    Anteversion angle at a standard supine anteroposterior pelvis view: mean 17.1o (range 6.2o to 31.9o, SD 4O)

    Position of the stem measured between the stem axis and the long axis of the femur: mean 0.17° varus (range 2.7o valgus to 3.3o varus, SD 0.9o)

    Length of hospital stay: 9.9 days (because of regulations of the hospital). Most of the patients were able to leave the hospital earlier.

    There was no radiological loosening of the components after a mean of 16 months.

    Key safety findings

    Complications: n=4 (only the first related to the surgical technique)

    Subluxations: n=2 (in both patients, there was no complete dislocation because the head was captured by the closed capsule).

    • 1 patient: subluxation happened at 3 weeks after the surgery during elevated sitting. This patient had a closed reduction and was doing fine 1 year after the surgery.

    • 1 patient: subluxation happened in the operating room after turning the patient onto the back. This needed immediate exchange of the head to a longer one. This demented patient walked without crutches after a few days without any complaints.

    Wound dehiscence: n=1 (the patients had a new skin closure at day 8).

    Femoral diaphyseal fracture at 4 weeks postoperation: n=1 (the patient was retransferred from the rehabilitation clinic and needed cerclage wiring of the femur and exchange of the stem).

    Study 7 NJR (2020a, 2020b, 2020c)

    Study details

    Study type

    Non-randomised comparative study (unpublished registry data)

    Country

    UK (multiple centres)

    Recruitment period

    Profemur L Classic Stem: 2014 to 2020

    Profemur L Modular Stem: 2004 to 2020

    Procotyl L Cup: 2004 to 2020

    Study population and number

    Profemur L Classic Stem: n=432,625 (782 patients having 829 primary THAs in which Profemur L Classic Stem was used; 431,843 patients having 501,339 primary THAs using all other cementless stems)

    Profemur L Modular Stem: n=433,020 (3,874 patients having 4,233 primary THAs in which Profemur L Modular Stem was used; 429,146 patients having 497,935 primary THA using all other cementless stems)

    Procotyl L Cup: n=683,939 (5,991 patients having 6,568 primary THAs in which Procotyl L Cup was used; 677,938 patients having 795,951 primary THAs using all other cementless cups)

    Patients with osteoarthritis, rheumatoid arthritis, avascular necrosis, fractured neck of femur, CDH/DDH or others

    Age and sex

    Profemur L Classic Stem:

    • Profemur L Classic Stem: mean 61.3 years; 46.9% male; BMI, median 28 kg/m2

    • All other cementless stems: mean 65.3 years; 44.4% male; BMI, median 28 kg/m2

    Profemur L Modular Stem:

    • Profemur L Modular Stem: Mean 63.4 years; 43.7% male; BMI, median 28 kg/m2

    • All other cementless stems: mean 65.3 years; 44.4% male; BMI, median 28 kg/m2

    Procotyl L Cup:

    • Procotyl L Cup: mean 63.9 years; 43.8% male; BMI, median 28 kg/m2

    • All other cementless cups: mean 66.1 years; 43.6% male; BMI, median 28 kg/m2

    Patient selection criteria

    Not reported

    Technique

    THA procedures with the use of the Profemur L Classic Stem, Profemur L Modular Stem, Procotyl L Cup or other cementless implants.

    Follow-up

    Profemur L Classic Stem - implantation time: mean 2.3 years (maximum 6.5 years)

    Profemur L Modular Stem - implantation time: mean 8.1 years (maximum 16.5 years)

    Procotyl L Cup - implantation time: mean 6.2 years (maximum 16.5 years)

    Conflict of interest/source of funding

    Not reported

    Analysis

    Study design issues: These NJR implant reports summarised usage and outcomes associated with the Profemur L Classic Stem, Profemur L Modular Stem and Procotyl L Cup. They also compared the outcomes of these implants with all other cementless implants in NJR.

    Study population issues: The reports included patients with various indications, although most had osteoarthritis. All patients had primary THA procedures. It was unclear how many procedures used the SuperPath approach. There is some patient overlap between reports.

    Key efficacy findings

    Number of patients analysed:

    • Profemur L Classic Stem: n=432,625 (782 patients having 829 primary THAs in which Profemur L Classic Stem was used; 431,843 patients having 501,339 primary THAs using all other cementless stems in NJR)

    • Profemur L Modular Stem: n=433,020 (3,874 patients having 4,233 primary THAs in which Profemur L Modular Stem was used; 429,146 patients having 497,935 primary THA using all other cementless stems in NJR)

    • Procotyl L Cup: n=683,939 (5,991 patients having 6,568 primary THAs in which Procotyl L Cup was used; 677,938 patients having 795,951 primary THAs using all other cementless cups in NJR)

    Key safety findings

    Revisions associated with the Profemur L Classic Stem, Profemur L Modular Stem and Procotyl L Cup

    Profemur L Classic Stem

    Profemur L Modular Stem

    Procotyl L Cup

    Death

    1.0% (n=8)

    13.9% (n=590)

    10.6% (n=696)

    Revision

    1.3% (n=11)

    5.0% (n=210)

    2.8% (n=187)

    Unrevision

    97.7% (n=810)

    81.1% (n=3,433)

    86.6% (n=5,685)

    Total

    100% (n=829)

    100% (n=4,233)

    100% (n=6,568)

    Profemur L Classic Stem findings
    Reasons for revision of primary procedures in which the classic stem was used – all bearing types

    Reason for revision

    Revised*

    Expected revisions**

    P value

    Unexplained pain

    2

    0.44

    0.073

    Dislocation/subluxation

    1

    2.27

    0.734

    Adverse soft tissue reaction

    0

    0.013

    1

    Infection

    3

    2.01

    0.46

    Aseptic loosening – stem

    0

    1.11

    0.634

    Aseptic loosening – socket

    1

    0.38

    0.318

    Periprosthetic fracture stem

    2

    1.23

    0.35

    Periprosthetic fracture socket

    0

    0.11

    1

    Malalignment stem

    0

    0.45

    1

    Malalignment socket

    1

    0.53

    0.413

    Wear of acetabular component

    0

    0.13

    1

    Lysis stem

    0

    0.05

    1

    Lysis socket

    0

    0.04

    1

    Implant fracture stem

    1

    0.08

    0.076

    Implant fracture socket

    0

    0.18

    1

    Implant fracture head

    0

    0.04

    1

    Dissociation of liner

    0

    0.14

    1

    Other/reason not recorded

    0

    0.43

    1

    Total revised

    11

    8.56

    0.388

    *Multiple reasons may be listed for one revision procedure.

    **Based on all NJR cementless stems, adjusted for age group, gender, indications and implantation year.

    Cox proportional hazards model for revision risk ratio of Profemur L Classic Stem / all other cementless stems in NJR, with endpoint as any revision

    Adjustment

    Hazard ration (95% CI)

    P value

    All bearings, Unadjusted

    0.92 (0.51 to 1.66)

    0.779

    All bearings. Adjusted for age, gender, year cohort and indications.

    1.29 (0.71 to 2.33)

    0.405

    Profemur L Modular Stem findings
    Reasons for revision of primary procedures in which Profemur L Modular Stem was used – all bearing types

    Reason for revision

    Revised*

    Expected revisions**

    P value

    Unexplained pain

    34

    26.45

    0.142

    Dislocation/subluxation

    38

    23.99

    0.007

    Adverse soft tissue reaction

    33

    37.46

    0.511

    Infection

    37

    21.60

    0.002

    Aseptic loosening – stem

    23

    31.93

    0.129

    Aseptic loosening – socket

    16

    16.14

    1

    Periprosthetic fracture stem

    19

    18.35

    0.814

    Periprosthetic fracture socket

    1

    2.31

    0.734

    Malalignment stem

    11

    5.05

    0.02

    Malalignment socket

    15

    10.15

    0.151

    Wear of acetabular component

    7

    8.32

    0.861

    Lysis stem

    6

    5.53

    0.828

    Lysis socket

    9

    5.33

    0.121

    Implant fracture stem

    13

    2.58

    <0.001

    Implant fracture socket

    3

    3.30

    1

    Implant fracture head

    1

    0.88

    0.587

    Dissociation of liner

    1

    3.39

    0.274

    Other/reason not recorded

    10

    9.81

    0.872

    Total revised

    210

    176.14

    0.012

    Components revised

    Components revised

    Number of procedures

    Profemur L Modular Stem

    All other cementless stems in NJR

    Femoral only

    44

    21%

    24%

    Acetabular only

    57

    27%

    33%

    Both femoral and acetabular

    80

    38%

    31%

    Neither femoral nor acetabular revision recorded***

    29

    14%

    12%

    ***Includes isolated head and/or liner exchange

    Cox proportional hazards model for revision risk ratio of Profemur L Modular Stem / all other cementless stems in NJR, with endpoint as any revision

    Adjustment

    Hazard ration (95% CI)

    P value

    All bearings, Unadjusted

    1.18 (1.03 to 1.35)

    0.017

    All bearings. Adjusted for age, gender, year cohort and indications.

    1.20 (1.04 to 1.37)

    0.010

    Excluding metal-on-metal, unadjusted.

    1.33 (1.13 to 1.55)

    <0.001

    Excluding metal-on-metal. Adjusted for age, gender, year cohort and indications.

    1.29 (1.10 to 1.51)

    0.002

    Procotyl L Cup findings
    Reasons for revision of primary procedures in which Procotyl L Cup was used – all bearing types

    Reason for revision

    Revised*

    Expected revisions**

    P value

    Unexplained pain

    23

    24.63

    0.84

    Dislocation/subluxation

    25

    29.37

    0.516

    Adverse soft tissue reaction

    11

    25.05

    0.003

    Infection

    38

    27.02

    0.042

    Aseptic loosening – stem

    22

    27.89

    0.296

    Aseptic loosening – socket

    8

    13.56

    0.17

    Periprosthetic fracture stem

    29

    24.81

    0.365

    Periprosthetic fracture socket

    1

    2.97

    0.382

    Malalignment stem

    7

    5.51

    0.515

    Malalignment socket

    9

    10.39

    0.875

    Wear of acetabular component

    2

    6.32

    0.105

    Lysis stem

    3

    4.27

    0.806

    Lysis socket

    1

    3.46

    0.277

    Implant fracture stem

    19

    3.27

    <0.001

    Implant fracture socket

    3

    3.36

    1

    Implant fracture head

    1

    0.99

    0.629

    Dissociation of liner

    0

    3.48

    0.056

    Other/reason not recorded

    9

    9.92

    1

    Total revised

    187

    179.45

    0.574

    Components revised

    Components revised

    Number of procedures

    Procotyl L Cup

    All other cementless cups in NJR

    Femoral only

    65

    35%

    22%

    Acetabular only

    37

    20%

    25%

    Both femoral and acetabular

    63

    34%

    43%

    Neither femoral nor acetabular revision recorded***

    22

    12%

    10%

    Cox proportional hazards model for revision risk ratio of Procotyl L Cup / all other cementless cups in NJR, with endpoint as any revision

    Adjustment

    Hazard ration (95% CI)

    P value

    All bearings, Unadjusted

    0.86 (0.75 to 1.00)****

    0.046****

    All bearings. Adjusted for age, gender, year cohort and indications.

    1.04 (0.90 to 1.20)

    0.570

    Excluding metal-on-metal, unadjusted.

    1.16 (1.00 to 1.35)

    0.052

    Excluding metal-on-metal. Adjusted for age, gender, year cohort and indications.

    1.16 (1.00 to 1.35)

    0.053

    ****Hazard ratio varied with time