Early results of total knee arthroplasty with a low contact stress anteroposterior glide.

PURPOSE: To present early results of 400 consecutive low contact stress (LCS) anteroposterior (AP) glide total knee arthroplasties (TKAs) performed by a single surgeon. METHODS: 304 consecutive patients aged 30 to 96 (mean, 66) years underwent 400 TKAs using LCS AP glides performed by a single surgeon. Only patients with an intact posterior cruciate ligament, a fixed flexion deformity of <15 degrees, and a valgus deformity of <15 degrees were included. Patients were assessed pre- and post-operatively using the American Knee Society (AKS) and Hospital for Special Surgery (HSS) scores. Range of motion was measured using a goniometer. AP and lateral radiographs were assessed for radiolucencies and osteolysis. RESULTS: The mean follow-up period was 4.2 (range, 1-8) years. The mean fixed flexion improved to 1 from 11 degrees and the mean active flexion improved to 120 from 111 degrees. Both AKS and HSS scores improved significantly. There were 28 anterior soft tissue impingements; 9 of them were in the first year of the study. Thereafter, the anterior lip of the bearing was modified and any offending osteophytes, soft tissue, or fat pads were excised. Of 39 (10%) knees that underwent re-operation (16 were due to anterior soft tissue impingement), 20 (5%) did not require change of the AP glide bearing and the remaining 19 were converted to a rotating platform bearing. No patellar baja was noted after fat pad excision. No patient had catastrophic wear or failure of the polyethylene bearing. The survival rate of the AP glide bearing was 95%. CONCLUSION: The early-to-mid-term outcomes of the LCS AP glide TKA are promising.

Lateral unicompartmental knee replacement: fixed or mobile bearing?

Between May 2001 and May 2003, 233 consecutive Preservation unicompartmental knee replacements (UKR) were performed. Of these, 30 were lateral UKRs (13%) performed in 12 men and 16 women (2 bilateral cases) with a mean age of 67 years (range 36-93 years). A metal-backed mobile bearing tibial component was used in 13 knees and an all-polyethylene fixed bearing tibial component in 17 knees. The patients were reviewed prospectively at 1 and 2 years. The 2 year results show no difference in range of motion or function between the mobile and fixed bearing versions of the Preservation knee when used on the lateral side. There were three early revisions, all in the mobile bearing group.

A retrospective comparative study of bilateral total knee replacement staged at a one-week interval.

The clinical results of bilateral total knee replacement staged at a one-week interval during a single hospital admission were compared with bilateral total knee replacements performed under the same anaesthetic and with bilateral total knee replacements performed during two separate admissions. The data were retrospectively reviewed. All operations had been performed by the same surgeon using the same design of prosthesis at a single institution. The operative time and length of stay for the one-week staged group were comparable with those of the separate admission group but longer than for the patients treated under one anaesthetic. There was a low rate of complications and good clinical outcome in all groups at a mean follow-up of four years (1 to 7.2). The group staged at a one-week interval had the least blood loss (p = 0.004). With appropriate patient selection, bilateral total knee replacement performed under a single anaesthetic, or staged at a one-week interval, is a safe and effective method to treat bilateral arthritis of the knee.

Cement penetration and stiffness of the cement-bone composite in the proximal tibia in a porcine model.

PURPOSE: To assess the stiffness of the cement bone composite and the depth and uniformity of cement penetration into the surface of the tibial component during total knee reconstruction in a porcine model. METHODS: The effectiveness of 3 protocols were compared: 2 commonly used cementing techniques-finger-packing of cement on the cut surface followed by impaction, and coating of the undersurface of the prosthesis with cement followed by impaction-and a new method using a tibial cement-pressurising device. Cement penetration was measured by computed tomography; stiffness was determined by hydraulic penetration testing. RESULTS: Cement penetration at a depth of 1 mm was significantly greater following coating the undersurface of the prosthesis than following finger-packing (p=0.008). There was no significant difference at deeper levels or between the tibial-pressurising device group and either of the 2 other groups at any level (p>0.3 in all cases). Differences in surface stiffness by tibial plateau region were found in tibiae that had been cemented using finger-packing and in those that had had their undersurface coated, but not in tibiae that had been cemented using the tibial-pressurising device. CONCLUSION: The tibial cement-pressurising device eliminated regional differences in stiffness seen with other cementing methods. Elimination of these differences by using this device should reduce micromotion and the incidence of aseptic loosening of tibial base plates in total knee arthroplasty.

Treatment of pathological fractures of the humerus with a locked intramedullary nail.

OBJECTIVE: The humerus is a common site for metastasis. Intramedullary nail fixation has been reported to be the best form of fixation for this disease but complications occur. This study aimed to assess the use of a new humeral nail to treat pathological fractures and impending pathological fractures of the humerus. METHODS: 29 patients received 31 Austofix locked intramedullary humeral nails: 25 for pathological fractures and 6 for impending fractures; 24 nails were inserted anterograde and 7 retrograde. Cement augmentation was applied in 4 patients, and adjuvant therapy was used in 28 patients. Complications occurred in 12 patients. RESULTS: Fixation failed in 6 patients: 2 due to intraoperative fractures during retrograde nailing, one due to a fracture through screw holes postoperatively, and 3 due to local progression of disease. Difficulty in distal locking of the nail was encountered in 4 patients. Locked intramedullary nailing resulted in a stable humerus in 80% of patients. CONCLUSION: Retrograde insertion of the nail is associated with an increased risk of intra-operative fracture, and disease progression can occur, despite the administration of adjuvant therapy.