The patellofemoral joint after total knee arthroplasty without patellar resurfacing

One hundred total knee replacements with a total condylar prosthesis and without patellar resurfacing were followed for a minimum of two years. Eighty-four per cent of the knees were affected by osteoarthrosis. Graded according to the knee-rating system of the Hospital for Special Surgery, there were eighteen excellent, fifty-three good, eighteen fair, and eleven poor results. At the most recent follow-up, twenty-nine knees (29 per cent), nine of which were affected by rheumatoid arthritis, were still painful in the patellofemoral area. The height and weight of the patient definitely influenced the amount of patellofemoral pain postoperatively. Small patients who had osteoarthrosis were exceptionally free of pain, regardless of sex, age, or level of activity. It seems that the best approach to patellofemoral replacement includes resurfacing of the patella in all patients who have rheumatoid arthritis and in patients who have osteoarthrosis if they have preoperative patellofemoral pain, are more than 160 centimeters tall, weigh more than sixty kilograms, and have advanced changes in the patella at the time of the operation.     

Reconstruction of patellar tendon rupture after total knee arthroplasty with an extensor mechanism allograft

Although patellar tendon rupture after total knee arthroplasty (TKA) is a rare complication, the consistently poor outcome of conventional tendon repair has convinced some to abandon such reconstruction in favor of a prospective protocol using an allograft distal extensor mechanism. The graft consists of a quadriceps tendon, a patella with a cemented prosthesis, a patellar tendon, and a tibial tubercle. Since December 1985, 13 knees in 12 patients were reconstructed using this method. Ten knees were followed for six to 51 months; five of these knees were followed for more than 24 months. Knee extension power and improved function were ultimately attained in all cases, although minimal extensor lags were present in three cases. Preoperative motion returned in all but one knee. Healing of the allograft to the host tissue was attained primarily at all of the tibial junctions. Two graft complications occurred, both in the first three months after surgery: one quadriceps junction treated by resuture failed at the one-month mark, and the other graft had to be revised for extensor weakness from rupture of the graft at the patella-patellar tendon junction, which was attributed to surgical damage to the tendon. After completion of healing to the host and rehabilitation of the knee joint, no grafts in the series failed during the course of normal daily activities. One patient fractured the allograft patella in a severe fall. The long-term durability of this construct needs to be studied further.     

Factors affecting patellar tracking after total knee arthroplasty

This study examined factors that influence patellar tracking after total knee arthroplasty. A total of 62 knees were evaluated radiographically for postoperative patellar tracking. Six factors were examined regarding their influence on postoperative patellar tracking. This study showed the effects of patellar component position, patellar resection angle, and lateral retinacular release on postoperative patellar tracking. There was no significant effect of the remaining 3 factors: the thickness of the patellar resection, preoperative patellar tilt, and rotational alignment of the femoral component. A medialized patellar component and obliquity of resection of the patella are effective for obtaining proper patellar tracking, whereas the evaluation of the influence of the external rotation of the femoral component requires more clinical studies.     

Reconstruction of a ruptured patellar tendon with achilles tendon allograft following total knee arthroplasty

BACKGROUND: Rupture of the patellar tendon after total knee arthroplasty is a rare and debilitating complication. Proper surgical management of this condition remains controversial. The purpose of this study was to review the results of reconstruction of a ruptured patellar tendon with an Achilles tendon allograft following total knee arthroplasty. METHODS: We reviewed our experience with the use of a fresh-frozen Achilles tendon allograft with an attached calcaneal bone graft to restore extensor function in nine patients with patellar tendon rupture following total knee arthroplasty (five primary and four revision). All patients were examined clinically and radiographically at an average of twenty-eight months. RESULTS: The average knee and functional scores improved from 26 and 14 points, respectively, before the surgery to 81 and 53 points after the surgery. The average extensor lag decreased from 44 degrees preoperatively to 3 degrees postoperatively, and the average range of motion of the knee increased from 88 degrees to 107 degrees. Two grafts failed in the early postoperative period. Both were repaired successfully. Radiographs showed an average proximal patellar migration of 17.8 mm, which did not appear to affect extensor function. CONCLUSIONS: This short-term follow-up study showed that once an Achilles allograft has healed, it can serve as a reliable reconstruction of a ruptured patellar tendon following total knee arthroplasty. This technique may be particularly suited for patients in whom the extensor mechanism was compromised by multiple prior operations. Continued follow-up is necessary to determine the long-term durability of these results.     

全膝关节置换术对髌骨内外倾运动的影响

目的探讨全膝关节置换术(totalkneearthroplasty,TKA)对髌骨内外倾运动的影响,及其在TKA术后膝前痛形成过程中所起的作用。方法采用6具成人尸体左侧下肢标本建立伸膝装置(股内侧、股中间、股外侧肌群按1.25∶1.5∶1的比例施以负荷)按比例负荷膝关节自由运动模型,应用激光束定位与X线摄片技术,分别测量正常膝关节与采用PFCΣ假体行人工膝关节置换术后膝关节屈曲过程中的髌骨内外倾角度。结果胫股关节屈曲30°、60°、90°、120°、150°时,以股骨滑车为参照标准,膝关节置换前后髌骨的倾斜角度分别是:0°±0°、0°±0°、0°±0°、0.24°±0.35°、-3.21°±1.80°;0°±0°、0°±0°、0°±0°、0°±0°、-1.12°±1.20°。三维空间参照系内,膝关节置换术前,膝关节屈曲0°、30°、60°、90°、120°、150°时髌骨平均外倾:0°±0°、-3.10°±2.25°、2.50°±1.07°、5.46°±2.60°、6.32°±2.16°、-2.10°±1.90°;膝关节置换术后,膝关节屈曲0°、30°、60°、90°、120°、150°时髌骨平均外倾:0°±0°、3.24°±0.35°、2.30°±1.39°、1.65°±1.17°、1.29°±1.03°、-0.86°±1.42°。结论TKA术后虽然髌骨与股骨滑车的对合关系保持正常,但在三维立体空间内髌骨的内外倾模式与幅度较未置换前发生了变化。膝关节初始屈曲时,TKA术前髌骨内倾,术后髌骨外倾,其变化的幅度与股骨假体外旋的幅度一致。膝关节屈曲60°￣120°范围内,TKA术后髌骨外倾较术前减小,而表现为相对内倾,内倾幅度与TKA术后股骨假体相对内翻的幅度一致。     

Position of the knee joint after total joint arthroplasty

A method for assessing knee joint position after surgery using the preoperative long-leg radiograph and the postoperative knee radiograph is described. Assessment of the formula has shown a near perfect correlation between the calculated position on the long-leg radiograph compared with the measured position for 44 knees. Three hundred eighteen knees after total joint arthroplasty were retrospectively reviewed and the postoperative position was determined. The preoperative position of the mechanical axis was 14.5 ± 37.3 mm medial to the knee joint center. Using the standing knee radiograph the postoperative position of the mechanical axis was 3.07 ± 9.2 mm lateral to the knee joint center, while the portable radiograph placed the mechanical axis 4.5 ± 12.4 mm medial to the knee joint center. There was a highly significant difference in the position of the knee joint center depending on the radiograph used for calculation (standing or portable). The difference between the two means was not due to opening of the knee joint, but likely due to change in the rotation of the knee in the presence of knee flexion. This series of the knee arthroplasties has a low projected rate of aseptic failure.     

Periprosthetic fractures after total knee joint arthroplasty

Periprosthetic fractures of the femur, tibia and patella are being registered with increasing frequency due to the rising numbers of total knee replacements. Depending on the site of the fracture, apart from mere traumatic mechanisms, implant specific parameters and implant loosening may represent the main causes of periprosthetic fracture. Moreover, general risk factors promote the manifestation of a periprosthetic fracture. Nowadays, valid classifications are available to categorize periprosthetic fractures of the femur, tibia and patella, and to create the basis for specific decision-making in choice of treatment. Despite a wide field of treatment options, the actual functional outcome after therapy and the high rates of complications imply that an adequate analysis of the fracture etiology and the corresponding transfer into an individualized treatment concept offer the chance of functional restoration of the patient similar to the pre-fracture state.     

Edge loading of patellar components after total knee arthroplasty.

Patellofemoral joint kinematics, contact areas, contact pressures, and contact patterns were assessed after total knee arthroplasty (TKA) using human cadaver knees. Two contemporary TKA systems with anatomic patellofemoral joints were implanted and tested under anatomically based loading conditions. An electromagnetic tracking system was used to evaluate patellofemoral kinematics, and Fuji pressure-sensitive film was used to determine contact areas, pressures, and patterns. Edge loading of patellar components was observed at higher knee flexion angles with both TKA systems. Peak contact pressures seen at the regions of edge loading exceeded the yield strength of ultra-high-molecular weight polyethylene. Efforts to reduce edge loading and contact pressures may decrease the incidence of patellofemoral joint complications and component failure after TKA.     

Failure of the all-polyethylene patellar component after total knee arthroplasty

From 1991 to 1996, 953 cases of porous-coated anatomic modular knee prostheses with all-polyethylene patellar components were implanted. Among them, 4 cases had breakage of the patellar component at the peg-button interfaces. One had loosening of the patellar component by cutting out the patellar bony bed. Heavy body weight, weakness of the pegs of the all-polyethylene patellar component, and osteonecrosis of the patella were conceived as the causes of failure.     

Revision surgery for patellar dislocation after primary total knee arthroplasty

This study evaluated risk factors for patellar dislocation after primary total knee arthroplasty and determined functional outcomes in patients following revision. Thirty-nine knees in 39 patients averaging 68 years (range, 27-91 years) at the time of revision were evaluated at a mean of 3.2 years (range, 2-7 years). Mean Knee Society and Function scores significantly improved from 34 and 35 to 77 and 54, respectively. Patellar dislocation most commonly resulted from errors in technique such as soft-tissue imbalance and malaligned components that led to poor tracking of the patella. Patellar tracking only improved after soft-tissue realignment in combination with revision of malaligned or loose components. Although revision significantly improved active knee extension and Knee Scores, two thirds of the patients had residual disabilities and pain.     

Patellotibial fusion for patellar tendon rupture after total knee arthroplasty

Patellar tendon rupture is a rare but recognized complication of total knee arthroplasty. Multiple repair methods have been described in the literature. This unique case involved a patient with an underlying metabolic disorder and poor soft tissue quality. A patellotibial fusion was used to achieve a more definitive reestablishment of the extensor mechanism and to improve the patient's level of activity.     

Use of a turndown quadriceps tendon flap for rupture of the patellar tendon after total knee arthroplasty

Patellar tendon rupture is a devastating complication after total knee arthroplasty. The results of surgical treatment of this complication were discouraging in most of the reports. We describe a case of rupture of patellar tendon 7 weeks after total knee arthroplasty treated with a turndown quadriceps flap and circumferential wiring. Two years and 6 months after operation, the patient had no extension lag of the knee and knee flexion to 110 degrees .     

Knee joint synovial cyst following total knee arthroplasty with bone allograft

Allograft has been shown to be highly successful for managing large osseous defects in total knee arthroplasty. We report a 68-year-old woman in whom a bone allograft had been used during total knee arthroplasty owing to a massive segmental medial tibia plateau defect 4 years earlier. Eighteen months after surgery, a 10 × 10 cm knee synovial cyst was detected by computed tomography scanning on the anteromedial side of the tibial plateau, and an en-bloc surgical excision was performed. At 36-month follow-up, a 16 × 12 cm cyst was found. Excision was again performed with removal of the allograft and application of an autologous iliac graft. After allograft removal, clinically and radiologically satisfactory results were achieved at the final follow-up.     

Fungal prosthetic joint infection after total knee arthroplasty

Fungal prosthetic joint infection after total knee arthroplasty (TKA) is a rare complication. Lacunae exist in the management of this complication. 62 year old lady presented with pain and swelling in left knee and was diagnosed as Candida tropicalis fungal infection after TKA. She underwent debridement, resection arthroplasty and antifungal plus antibiotic loaded cement spacer insertion, antifungal therapy with fluconazole followed by delayed revision TKA and further fluconazole therapy. Total duration of fluconazole therapy was 30 weeks. At 2 year followup, she has pain less range of motion of 10^°-90^° and there is no evidence of recurrence of infection.     

Lateral patellar chamfer in total knee arthroplasty

Derangement of the anterior compartment of the knee can cause patellofemoral dysfunction in up to 50% of secondary surgeries after total knee arthroplasty. A technique of patellar chamfering is described that can minimize the risk of anterior knee pain from lateral patellar impingement without compromising bone stock for future operations.     

全膝关节置换术髌骨相关问题的探讨

髌骨是人体最大的籽骨，它是伸膝装置的重要组成部分，在20世纪的早、中期，髌骨的重要性并不为人们所重视。自1971年Kaufer报告髌骨的机械力学功能以来，髌骨的重要性也越来越为人们所认识，众多研究证实，髌骨对全膝关节置换（totalkneearthroplasty,TKA）术后的功能恢复有着重要的影响。一、髌骨的解剖及功能髌骨厚度为2～3cm，其中关节软骨最厚处可达5mm。髌骨后表面的上3/为关节面，共七个，由纵向的中央嵴及内侧嵴分为外侧关节面、内侧关节面和奇面，内、外侧关节面又被两条横嵴分为上、中、下三部分。髌骨后表面的下1/位于关节外，…     

Excisional arthroplasty for patellar loosening in total knee arthroplasty

Four thousand two hundred eighty-seven cases of Anatomic Graduated Components total knee replacements with a cemented, single-peg, all-polyethylene patellar component were performed at our institution over the past 15 years. One hundred eighty cases of patellar component loosening were found. Eleven knees (0.3%) in 11 patients required isolated patellar component reoperation. In all cases, the patellar component was excised and not reimplanted. The average follow-up for the 11 patients was 2.2 years. Five had a complete minimum follow-up of 2 years following reoperation. Pain and function were improved. Complications included infection in 3 knees and extensor lag in 1 knee. Because of the complication rate associated with isolated patellar component excision caused by a loose patellar component, we recommend surgical removal of the patellar component only in cases of severe pain and/or prominence of the component.