chapter 13: Surgical Treatment of Patellofemoral Chondrosis and Arthrosis
OTHER SURGICAL ALTERNATIVES FOR THE PATELLAR ARTHROSIS PATIENT
Although it is rightfully considered the end of the line, patellectomy can lead to satisfactory results. These are better if the patellofemoral joint alone is affected (45‑50). For older patients, not needing full quadriceps power, and more likely to have loss of flexion, the patellar splitting technique (51) offers the advantage of immediate mobilization. Debeyre et al (52) have also reported good results with patellectomy for arthrosis, but Ackroyd and Polyzoides (53) reported only 53% good results after patellectomy. It is important when reviewing the literature on patellectomy to remember that results may be different for different conditions treated [chondromalacia (54), fracture, arthrosis (46)]. Nonetheless, patellectomy is a more questionable alternative (55), now that other techniques are available for the patient with patellar arthrosis. Kelly and Insall (56) emphasized that alternatives to patellectomy can usually be found. There is little argument, however, that a good patellectomy may be the best way to improve function and reduce pain in selected patients. Lennox et al (57) found 76% good results following patellectomy at 12 to 48 year follow‑up. Patients with osteoarthritis, however, did less well.
The essentials of the technique we use were reported by Boyd and Hawkins (51). The patella is approached through a vertical midline anterior incision (Fig. 13.39). The midportion of the quadriceps tendon and the patellar tendon are carefully identified and incised in the direction of their fibers into the joint. The insertion of the extensor apparatus into the patella is incised in the midpatellar line, taking care that the patella is divided into equal halves. A malleable retractor is introduced into the joint proximally and distally to protect the trochlear surface, and the patella is divided longitudinally with an osteotome. The patella is now enucleated by grasping each half in turn with a towel clip and working from the undersurface of the quadriceps expansion from superior to the midportion of the patella and then inferiorly to the midportion of the patella. This facilitates a clean division of the fibers and preserves an intact, tough fascial covering that is in continuity from the quadriceps tendon to the patellar tendon. Depending upon what is necessary intra‑articularly, the quadriceps tendon can be split in the midline proximally as far as 10 cm and the patellar tendon can be split down to the tibial tubercle. The wound is closed by imbricating one side over the other in a double row of interrupted sutures. Flexion on the table to 90 degrees without stressing the suture, line is possible and should be carried out. If necessary, the lateral retinaculum can be divided at the level of the anterior border of the iliotibial tract to help centralize the extensor mechanism. It is extremely important to imbricate adequately to avoid impingement of the lateral extensor mechanism over the lateral condyle. Snapping in this region can cause postoperative pain.
Postoperatively, the patient is managed in a compression dressing and posterior splint. Full vigorous quadriceps exercises are possible immediately, and the patient is encouraged to straight leg raise in the splint. The splint is removed daily starting on the fifth postoperative day so that both active flexion and extension exercises may be performed. Most patients achieve 90 degrees of flexion 2 weeks postoperatively. This technique is particularly advantageous if other intra‑articular surgery has been necessary.
In one study on the mechanical function of the patella, there was a reduction of 15% of extensor power with patellectomy and transverse closure, but a 30% reduction with longitudinal closure (57). However, their longitudinal closure was side‑to‑side without imbrication and it is likely that the quadriceps power was being transferred to the tibia through the retinacula, rather than through a central tendon with consequent reduction in extensor moment arm. In those cases in which we have employed the longitudinal imbricated closure, there has been no extension lag. Also, mobilization of the knee has been much less of a problem with the longitudinal closure technique.
Butler‑Manuel et al have noted increased uptake in the femoral groove on scintigraphy of post‑patellectomy patients (58). This raises some questions regarding the longterm fate of the femoral trochlea post patellectomy, but does not negate the validity of the procedure as a salvage operation.
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