All patients should undergo a full course of non-operative conservative management prior to any invasive procedure. The use of anti-inflammatory analgesics in addition to intensive rehabilitation under physiotherapy control can solve many patients’ problems. The use of McConnell strapping, dual bio-feedback, patella bracing and isokinetic rehabilitation provides a selection of options for patients with early disease.

Failure of symptomatic improvement constitutes the indication for further investigations and treatment. Radiographic assessment with dynamic CT scans or MR will provide useful information to assist with planning surgical treatment. Arthroscopic assessment will help to evaluate the alignment of the patellofemoral joint and give more detailed information about the state of the articular surfaces. It is important to recognise that the magnification effect of arthroscopy will make articular cartilage lesions appear several times bigger than they are in reality. Description of arthroscopic assessment and treatment has been fully described in the earlier section on investigations.

Arthroscopic chondrectomy can be beneficial to remove loose flaps of articular cartilage and tidy up areas of chondral irregularity. Although this will not promote healing of the chondral lesion, if followed by intensive rehabilitation, marked improvement in symptoms can occur in some cases. The addition of abrasion arthroplasty or microfracturing may be appropriate in more extensive and deeper lesions.

If there is any degree of malalignment of the patella or impingement of chondral lesions as flexion occurs then distal tibial tubercle realignment procedures can be very helpful. Careful analysis of the precise characteristics of the malalignment and details of the position and extent of the chondral lesions is essential to plan the treatment. The French group in Lyon have pioneered realignment procedures for the treatment of lateral overload and subluxation using the Elmslie Trilat technique. This can be refined and performed under arthroscopic control. Preliminary arthroscopic assessment is performed as described above and an extra-articular mid lateral release of the lateral retinaculum performed maintaining the integrity of the lateral synovium.

Coronal osteotony of the tibial tubercle   

Osteotomy completed with a thin osteotome

Medical displacement of the tubercle of 12-16 mm and temporary fixation

This is performed under direct vision through a small lateral lazy S incision and the inferior lateral geniculate vessels can be secured. The Elmslie procedure is performed with an osteotomy of some 5cm to 7 cm leaving an intact tongue of bone at the distal end. Medial translation of the tibial tubercle can be performed up to 75% of the osteotomy surface and slight anteriorisation can be achieved by altering the angle of the osteotomy in the transverse plane. After initial displacement temporary fixation is performed to allow arthroscopic assessment of the patella tracking and stability. Further medial displacement can be performed if necessary though it is important not to exceed 75% of the osteotomy surface. The osteotomy is then secured with two fully threaded 4.0mm lagged cancellous screws. The heads countersink into the cortical bone of the tubercle and seldom cause problems. Petalling of bone on the lateral side will fill any gaps in the osteotomy and promote union.

     
Five years post operation of an Elmslie realignment for subluxation.

If there is persistent malalignment in the more severe degrees of lateral subluxation or persistent instability then a medial plication of the vastus medialis retinaculum can be performed through a small medial extra-articular incision. It is important not to over-tighten this repair for fear of producing medial overload or even medial subluxation. More recently a more dynamic reconstruction has been used with hamstring tendons to reinforce the medial patellofemoral ligament.  Although early results of the Elmslie procedure have been reported as satisfactory, deterioration tends to occur with time with the onset of arthritic signs and symptoms. Nakagawa (1)

In cases with lesser degrees of lateral malalignment and subluxation Fulkerson’s osteotomy may be preferred. The angle of the osteotomy can be varied to create more anteriorisation or medialisation depending on the nature and position of the articular cartilage lesions of the patella and the degree of malalignment. Details of this procedure are described by Fulkerson (2) but considerable judgement is required to match the osteotomy with the chondral lesion.

In cases with pure lateral facet osteoarthritis, lateral facetectomy has been advocated by some authors. There is, however, no clear evidence of the quality or longevity of results from this procedure.

Patellectomy has traditionally been used as a salvage procedure for patellofemoral disorders. It has an uncertain outcome and many reports record good or excellent results in less than 50% of cases. Ackroyd & Polyzoides (3) Weakness of the extensor mechanism is an inevitable consequence and poor results can be expected if there is any degree of trochlea dysplasia or persistent malalignment of the extensor mechanism.

CT scan after patellectomy showing trochlear displasia and persistant subluxation

Treatment of Established Patellofemoral Disease with an arthroplasty.

Patellofemoral arthroplasty was first reported by McKeever 1955 (4). Development of the procedure led to several designs being widely used in the 1970s. Reasonable short-term results have been reported using the Richards’ and Guepar (5 - 10) designs. The Lubinus prosthesis was designed in 1974 (Ref 11). The results have proved disappointing in the medium term with only 50% successful results at 7.5 years. Nevertheless nearly half the patients continued to experience excellent function and pain relief suggesting that improvements in design may eliminate some of the problems (ref 12-13). Most series have reported difficulties with achieving satisfactory patella alignment and persistent subluxation leading on to wear has been a feature of many reports. The second major cause of failure is disease progression, which has been reported from 5% to 10% in most studies. Indeed Kooijman et al in recent long-term reviews of up to fifteen year follow-up, reported disease progression in over 20% of cases.(Ref 14-15)

References

1. Nakagawa K, Wada Y,  Minamide M, Tsuchiya A and Moriya H)  Deterioration of long term clinical results after the Elmslie-Trillat procedure for dislocation of the patella.  J Bone Joint Surg 2002; 84-B: 861-4).
2. Fulkerson JP. Anteriorisation of the tibial tuberosity for patellofemoral malalignment. Clin Orthop 1983; 177: 176.
3. Ackroyd CE, Polyzoides AJ. Patellectomy for Osteoarthritis. A study of 81 patients followed for 2 – 22 years. J Bone Joint Surg (Br) 1978; 60-B: 353-7.
4. McKeever DC. Patellar prosthesis. J Bone Joint Surg (Am) 1955; 37-A: 1074-1084.
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8. Krajca-Radcliffe JB, Coker TP. Patellofemoral arthroplasty: a 2 to 18 year follow-up study. Clin Orthop 1996; 330: 145-151.
9. Witvoet J, Benslama R, Orengo P, et al. Guepar femoropatellar prosthesis: description: Initial results. Rev Chir Orthop Reparatice Appar Mot 1983; 69(Suppl 11): 156-158.
10. Witvoet J. Etat Actuel des Prostheses Femoro-patellaires. In Chasiers d’enseignement de la Sofcot. Expansion scinitifique Francaise. 1994; 46: 79-92.
11. Lubinus HH.  Patella glide bearing total replacement. Orthopaedics 1979; 2: 119-127.
12. Smith AM, Peckett WRC, Butler-Manual PA, Venu KM, d’Arcy JC.  Treatment of patellofemoral arthritis using the Lubinus patellofemoral Arthroplasty: A retrospective review. The Knee 2002; 9: 27-30.
13. Tauro B, Ackroyd CE, Newman JH, Shah NA. The Lubinus patellofemoral arthroplasty. (J Bone Joint Surg (Br) 2001; 83-B: 696-701.
14. Kooijman HJ, Driessen APPM, van Horn JR. Long-term results of patellofemoral arthroplasty. J Bone Joint Surg (Br) 2003; 85-B: 836-840.
15. Cartier P, Sanouiller JL and Khefacha A. Long term results with the first patellofemoral prosthesis. Clin. Orthop. 2005; 436: 47-54 Argensen JN