The National Institute for Health and Care Excellence (NICE) has issued full guidance to the NHS in England, Wales, Scotland and Northern Ireland on Arthroscopic trochleoplasty for patellar instability, in January 2014.


Patellar instability occurs when the patella fails to engage securely in the trochlea at the start of flexion; it slips laterally and either dislocates completely or slips back medially to its correct position as flexion continues. In some patients this happens because the trochlear groove is too shallow or uneven (trochlear dysplasia).

Conservative treatment includes physiotherapy and exercises to strengthen the quadriceps. Surgical approaches include direct reconstruction of the dysplastic trochlea or correction of associated factors by procedures such as medial patellofemoral ligament reconstruction. Trochleoplasty aims to reshape the bony anatomy of the trochlea: it may involve deepening the groove or elevating the lateral wall of the trochlea (which should be higher than the medial). Trochleoplasty is usually done as an open procedure, which is associated with risks such as arthrofibrosis and rarely infection.

Coding recommendations

W77.5 Periarticular osteotomy for stabilisation of joint

Y76.7 Arthroscopic approach to joint
Z76.5 Lower end of femur NEC
Note that the patellofemoral ligament reconstruction would be coded in addition

In addition one of the following ICD-10 codes would be recorded

M23.5 Chronic instability of knee
or a fourth character code from the following category:
M22.-Disorders of the patella

Your responsibility

This guidance represents the view of NICE, arrived at after careful consideration of the evidence available. When exercising their judgement, healthcare professionals are expected to take this guidance fully into account, and specifically any special arrangements relating to the introduction of new interventional procedures. The guidance does not override the individual responsibility of healthcare professionals to make decisions appropriate to the circumstances of the individual patient, in consultation with the patient and/or guardian or carer. 

All problems (adverse events) related to a medicine or medical device used for treatment or in a procedure should be reported to the Medicines and Healthcare products Regulatory Agency using the Yellow Card Scheme.

Commissioners and/or providers have a responsibility to implement the guidance, in their local context, in light of their duties to have due regard to the need to eliminate unlawful discrimination, advance equality of opportunity, and foster good relations. Nothing in this guidance should be interpreted in a way that would be inconsistent with compliance with those duties. Providers should ensure that governance structures are in place to review, authorise and monitor the introduction of new devices and procedures.

Commissioners and providers have a responsibility to promote an environmentally sustainable health and care system and should assess and reduce the environmental impact of implementing NICE recommendations wherever possible.

  • National Institute for Health and Care Excellence (NICE)