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The patellofemoral joint in total knee prostheses. Design considerations.

Some desirable design features of the patellofemoral joint in a total knee arthroplasty condylar prosthesis are proposed. These are that the femoral element should be grooved, have a high anterior flange, and be circular as viewed from the side. The groove should be about 5 mm deep and have relatively vertical walls. The patellar component should have a saddle-shaped articular surface matching the femur and should be countersunk into the patella. The components should be placed so as to position the joint automatically. Results with such a design are reported; loosening, wear, dislocation, and fracture have been rare. Osteolysis of the patella has not been seen after 9 years, so that the cementless press-fit fixation of an H.D.P. patellar prosthesis to date seems safe and efficacious.

Aged↗

Medial patellofemoral ligament reconstruction with semitendinosus autograft for chronic patellar instability: a follow-up study.

PURPOSE: The purpose of this study was to describe the long-term results of medial patellofemoral ligament reconstruction with a free semitendinosus graft. TYPE OF STUDY: Prospective nonrandomized study. METHODS: We assessed 15 patients (16 knees) treated between 1992 and 1996 (follow-up > 5 years). Diagnosis of patellofemoral dislocation or subluxation was based on the patient's report plus reproduction of subjective complaints of instability on physical examination. All patients were treated by the same surgeon. Assessment was performed by a different surgeon based on Crosby-Insall and Aglietti criteria. RESULTS: According to Crosby-Insall criteria, 11 knees were rated as excellent, 4 good, and 1 poor. According to Aglietti criteria, 11 knees were rated as excellent, 3 good, 1 fair, and 1 poor. According to both protocols, 15 knees showed negative apprehension test, absence of patellofemoral pain, and normal patellar tracking. In one knee, the apprehension test was positive, patellofemoral pain was present, and patellar tracking was abnormal. Patellofemoral crepitus was detected in 10 knees (attenuated in 6). Thirteen patients (14 knees) were satisfied with the results. One patient considered the result acceptable, but below expectations. The final patient underwent an additional procedure. No cases of infection and no vascular problems were seen. CONCLUSIONS: Medial patellofemoral ligament reconstruction proves to be useful in improving unstable extension mechanisms and in preventing insecurity, gradual joint deterioration, and disabling pain during dislocation episodes, in a minimal 5-year follow-up study. LEVEL OF EVIDENCE: Level IV.

Adult↗

Optimizing patellofemoral tracking during total knee arthroplasty.

Fifty-seven patients who underwent 65 primary TKAs between 1993-1994 were retrospectively studied to identify the technical challenges and pitfalls associated with patellar resurfacing and to improve patellar tracking during total knee arthroplasty (TKA). Average patient age was 69 years. All surgeries were performed by a single surgeon (J.N.I), and the same prosthesis was used in all patients. Intraoperatively, attention was paid to avoid femoral and tibial component malrotation and prevent overstuffing of the patellofemoral joint. Preoperative limb alignment was varus in 42 knees, neutral in 6 knees, and valgus in 17 knees. Average pre-resection patellar thickness measured 23.8 mm and post-resection thickness averaged 21.5 mm. No patella-prosthesis composite was thicker than the native patella. Two (3%) knees required a formal lateral release to improve patellar tracking at surgery. Average follow-up for 53 patients (61 knees) was 5 years. At latest follow-up, 4 (6%) patients reported mild anterior knee pain, 5 (7%) patients reported pain with stairs, and 2 (3%) patients had knee crepitus without pain. No dislocations or recurrent subluxations occurred. No patient required revision surgery for patellofemoral complication. Awareness of the anatomic variability, attention to component rotation, and restoration of the normal patellar height improves patellar tracking and minimizes patellofemoral instability following TKA.

Aged↗

Knee dislocation: treatment of high-velocity knee dislocation.

BACKGROUND: We report the outcomes of patients treated with a new arthroscopic treatment modality for knee dislocation after high-velocity trauma. METHODS: Twenty-three patients (12 men, 11 women; 25 knees) with traumatic knee dislocation were treated with this technique. Under arthroscopy with gravity inflow irrigation, the ruptured posterior cruciate ligament was reconstructed with a patellar bone-tendon-bone graft, and the anterior cruciate ligament was debrided subacutely. The collateral ligament, meniscus, and capsules were repaired through additional incisions. RESULTS: The average interval between injury and surgery was 11.1+/-5 days (range, 5 to 25 days). After a mean follow-up period of 27.2+/-7.86 months, the mean extension was 1+/-2 degrees and the average flexion was 129.6+/-4.91 degrees. The mean Lysholm score was 84. There were no major complications. CONCLUSION: Arthroscopic posterior cruciate ligament reconstruction seems to be an effective treatment for traumatic knee dislocation.

Adolescent↗

Congenital dislocation of the patella and its operative treatment.

Twelve patients with 18 knees whose congenital permanent lateral dislocation of the patella was irreducible by nonoperative means are reported. All knees were operated on according to the same principles, including medial transfer of the patellar tendon. The age of the patients at operation varied between 3 and 19 years. The average follow-up time was greater than 13 years. All patients benefited greatly from the operation. Active knee extension ability was restored in all knees. Some extension deficit remained in two severely dysplastic patients. Congenital subluxation with habitual dislocation of the patella has been successfully treated by the method described.

Adolescent↗

The percutaneous lateral retinacular release.

This study reviews 34 of 37 original patients who were reviewed in 1981 after previously undergoing percutaneous lateral retinacular release. Short-term satisfactory results regarding reduction of pain and prevention of dislocation were maintained on this second followup (average, 48 months). With this increase in postoperative time, patients with recurrent subluxation developed an increase in patellar slipping. Patients with chondromalacia and degenerative joint disease are less suited for long-term treatment. Long-term problems occurred in 1 of 34 patients (3%).

Follow-Up Studies↗

Biomechanics of the patellofemoral joint.

The patellofemoral joint contains 2 complex mechanisms for ameliorating forces transmitted across it, namely increasing extensor lever arm-r in the important range of flexion 30 degrees-70 degrees and increasing contact area with increasing flexion. In this range the patella bears sole responsibility for transmitting resultant flexion of quadriceps force to the femur. Here lies the thickest cartilage in the body and perhaps not surprisingly, the most frequent site of cartilage degeneration. The Q-angle and valgus vector explain the predominance of the pathologic lesions on the lateral side of the joint as well as the associated dislocations, subluxations, lateral pressure syndromes, and patellofemoral arthrosis. Extension exercises against resistance produce non-physiologic loading of patellar articular cartilage. Even relatively small loads which are commonly used in physical therapy departments produce pressures far in excess of normal activities, such as stair climbing or squatting. Patients who are placed on such exercise programs are often made worse and develop symptoms which they did not have before. Straight leg raising with weights, on the other hand, maximally stresses the quadriceps muscle without any patellofemoral compression since the patella is out of contact, proximal to the trochlea.

Adolescent↗

Restoration of patellofemoral congruity by combined lateral release and tibial tuberosity transposition as assessed by MRI analysis.

Twelve knees in eleven patients with subluxation or dislocation of the patella were assessed by MRI at 0, 10, 20 and 30 degrees of knee flexion, before and after vastus lateralis release and medial transplant of the tibial tuberosity. The preoperative position of the patella deviated the greatest from normal in 0-20 degrees of knee flexion. The operations were found to correct the lateral patellofemoral angle and the lateral patella tilt with or without quadriceps muscle contraction, but did not completely correct the marked preoperative lateral patellar displacement and tracking.

Adult↗

[Significance of lateral release in the therapy of patellar chondromalacia].

A retrospective study was performed in 26 patients who underwent an operation for femoro-patellar pain due to a patellar chondromalacia with or without minor patellar dislocation/lateral pressure syndrome. The average age of the patients was 28.5 (15-39) years. 22 of the 26 patients revealed minor chondral damages of the stages 1 and 2 according to Outerbridge. In 12 patients ("lavage" group), an arthroscopic joint debridement only was carried out, while an additional open, lateral retinaculum release was made in 14 patients ("lateral release" group). The patella's distance of dislocation according to Hepp was reduced on an average of 3.0 (0-7) mm (p = 0.0019). The results of Bentley's score obtained during the follow-up interval on an average of 30.1 (9 to 60) months were almost identical for both groups. "Good" and "very good" results were achieved in the "lavage" group (83.3 %) and "lateral release" group (78.6 % of the patients). Lateral release should be used in cases of patellar decentration between 5 and 10 mm and adequate pain symptoms. The post-operative distance of dislocation should be less than 5 mm. Under such conditions and with minor chondral damage, a combined approach by using an arthroscopic joint debridement and open lateral release is promising to treat a patellar dislocation/lateral pressure syndrome.

Adolescent↗

Talonavicular dislocations and midfoot arthropathy in neuropathic diabetic feet. Natural course and principles of treatment.

Talonavicular dislocations, sometimes associated with other midtarsal arthropathy, occasionally occur in patients with diabetic neuropathy. The natural course and rationale of treating this diabetic arthropathy is presented, based on the literature and the authors' experience with eight cases. Appropriate management depends on the acuteness of the injury, the degree of deformity, and the degree of bone fragmentation. If the injury is acute and alignment is acceptable, immobilization and protective weight bearing may prevent progression of the neuropathic joint destruction. If dislocation is acute with marked deformity but there is little fragmentation and the foot has intact circulation, reduction and surgical arthrodesis may be indicated. If dislocation is chronic, with bone fragmentation and severe deformity, proper management consists of wearing custom-molded shoes with stiff rocker-bottom soles. Patellar tendon weight-bearing braces may be added if needed. For patients in this last category, surgical treatment is recommended as a last resort only if soft-tissue breakdown cannot be prevented by appropriate footwear and bracing alone.

Adult↗

[Results in patello-femoral joint replacement in various knee endoprostheses (Type GSB and ES)].

105 patients with 137 total knee replacements (105 model GSB, 32 model ES) were reexamined 4.3 years (2 to 9.7 years) postoperatively. 63.9 percent suffered from chronic polyarthritis. The clinical result (Insall 100-point score) averaged 73.6 points (78.2 ES-, 71.7 GSB II-knees). In 28.6 percent of the GSB- and 3.1 percent of the ES-knees osteolyses of the patella were apparent. Subluxation or complete dislocation of the patella was present in 85.7 percent of the GSB- and 25 percent of the ES-knees. The result was dependent on the preoperative knee axis, patellar height and the implant site of the tibial component. Revisions with complete removal of the inlay were most successful.

Adult↗