Patellofemoral arthrosis: Proper diagnosis, indications and surgical techniques are essential

By Joseph Pagkalos, MRCS(Ed), Lancaster, United Kingdom

During the symposium Patellofemoral Arthrosis, Dr. Ramon Ferran Montserrat moderated presentations by: Philippe Neyret, MD; David Dejour, MD; John H. Newman, FRCS; and Sander Koëter, MD.

The first presentation by Dejour focused on the data from a multicenter study conducted in France on patients with isolated patellofemoral arthrosis (IPFA). Interesting results from this study included the lower incidence of progression to arthritis in patients with instability against patients with no instability, 32% vs. 41%, as well as the slow progression in the instability group who took an average of 18 years to progress to severe (stage IV) disease.

He concluded by stressing the better natural progression of the patients with instability which makes them better candidates for less invasive treatment.

Assessment parameters

The symposium continued with Neyret from the University of Lyon who focused on assessment parameters and treatment options for the dislocating and maltracking patella. The value of the distance between the tibial tubercle and the center of the groove (TT–TG) and the patellar tilt, which can be accurately measured by CT scanning, were presented.

Regarding the treatment options available, Neyret presented the encouraging results of medial patellofemoral ligament (MPFL) reconstruction from 35 cases at his institution. A reduction of the tilt by 7.5· at a mean 18-month follow-up is promising and he expressed the belief that due to the better biomechanical restoration achieved with MPFL reconstruction, the results will outweigh the ones of the vastus medialis obliquus plasty.

Diagnosis

Koëter of St Maartenskliniek in the Netherlands, stressed the need for satisfactory diagnosis, as the results of surgeries performed without clear indications of instability are poor. A prospective trial performed in the Netherlands included two groups, one with confirmed dislocation of the patella and one without, which underwent a tibial tubercle osteotomy.

Whilst presenting the operative technique, Koëter suggested the preservation of the medial and posterior soft tissue planes as they can be very important for the blood supply. Using a stable pivot point in the distal part of the osteotomized tubercle to correct the alignment, the authors reduce the risk of overmedializing. The results of the technique are encouraging with good pain relief, correction of the alignment and reduced risk of overmedializing.

Montserrat, the chairman of the symposium, gave the results of a series of 83 knees operated on at his institution. The most current follow-up was 11 years of these patients who underwent operative realignment of their paella with lateral partial facetectomy, excision of lateral osteophytes and Insall’s musclular plasty were presented. At 11 years, a significant percentage of the patients who had the procedure, 37%, progressed to have a TKA. This was associated with increased preoperative (medial) pain, and severe disease as demonstrated by clinical (Kujala score) and radiological (Ahlbäck score) terms.

Patellofemoral replacement

The final presentation of the session was given by Prof. Newman from the Avon Orthopaedic Centre in Bristol, UK on the patellofemoral replacement. With the experience of 600 replacements under his belt, the speaker started with the shift to more strict criteria for replacements in his practice.

He said that the key indication for replacing the patella in arthritis is IPFA with instability and/or dysplasia of the femur in the young patient. A key point for the surgeon who is called to assess a patient for replacement is to ensure the accurate diagnosis of dysplasia, as this is not accompanied by dislocation in many cases.

Newman also stressed the fact that the replacement of the patella should be considered a soft tissue operation in which material may be used, but the primary concern should be the restoration of biomechanics.