Purpose: Spontaneous osteonecrosis of the knee is a potentially greatly debilitating condition. While success has been reported with non-operative treatment of this disorder in its earliest stages, knee arthroplasty is the only viable modality if allowed to progress to condylar collapse. The purpose of this report is to review the etiologic and pathophysiologic principles of spontaneous osteonecrosis of the knee, to present our experience with joint-preserving surgical treatment of this condition, and finally to introduce a treatment algorithm developed based on this knowledge.

Method: Seventeen patients with a clinical and/or radiographic a diagnosis of spontaneous osteonecrosis of the knee, and exclusion of secondary osteonecrosis, who failed non-operative modalities were treated with joint-preserving surgery at a single center between January 2000 and December 2006. Treatment modalities included arthroscopy, and either percutaneous core decompression and/or osteochondral autograft transfer. Three knees were lost to follow-up, leaving 14 knees with a mean follow-up of 37 months (range, 11 to 84 months).

Results: Twelve of 14 knees (86%) had knee joint survival with a mean Knee Society Score of 80 points (range, 45 to 100 points) at final follow-up. One patient was treated with serial core decompression followed by osteochondral transfer, and was included in both groups. Six of 7 patients (86%) treated with core decompression alone had a successful clinical outcome, as did 7 of 8 patients (87%) treated with osteochondral autograft transfers. Two patients (14%) progressed to condylar collapse, and were treated with total knee arthroplasty with successful results.

Conclusion: Based on these results, we propose a treatment algorithm that begins with non-operative treatment, followed by joint-preserving surgery consisting of arthroscopy, core decompression, and/or osteochondral autograft transfer. Although our sample size is small, the results suggest that this proposed treatment algorithm can successfully postpone the need for knee arthroplasty in selected patients with pre-collapse spontaneous osteonecrosis of the knee.

Purpose: Many strategies have been reported for decreasing the cost of orthopaedic procedures, including negotiating lower prices with manufacturers and using lower-cost generic implants, but prosthetic waste has not been investigated. The purpose of this study was to characterize the present and potential future cost of intra-operative waste of hip and knee implants.

Method: A regional prospective assessment of implant waste was performed from January 2007 to June 2008, evaluating the incidence and reasons for component waste, the cost of the wasted implants, and where the cost was absorbed (hospital or manufacturer). Using published data on nationwide arthroplasty volumes, the results were extrapolated to the whole of the United States. Finally, based on peer-reviewed estimates of nationwide arthroplasty volumes for the next 20 years, a projection was made about the future cost burden of implant waste.

Results: Implant waste occurred in 79 of 3443 recorded procedures (2%), with the surgeon bearing primary responsibility in 73% of occurrences. The annualized waste cost was $109,295.35, with 67% absorbed by the hospital. When extrapolated to the whole of the United States, the annual cost to hospitals of hip and knee prosthetic waste is $36,019,000, and is estimated to rise to $112,033,000 in current dollars by the year 2030.

Conclusion: This study discovered a notable incidence of intra-operative hip and knee implant waste, with the majority of cases attributed to the surgeon, and representing an important additional cost burden on hospitals. With arthroplasty rates projected to increase markedly over the next twenty years, this waste represents a potentially noteworthy target for educational programs and other cost containment measures in orthopaedic surgery.

Purpose: Minimally-invasive total knee arthroplasty has generated tremendous recent interest, but there have been reports of complications resulting from these new techniques. However, most studies have less than one year follow-up and are anecdotal in their results. The purpose of this study was to retrospectively evaluate a series of 1,000 consecutive minimally invasive total knee arthroplasties, to describe the clinical and radiographic complications of this technique, to determine whether complication rates changed with experience, and finally to compare complication rates to a match group operated by the same surgeon.

Method: Clinical and radiographic data were reviewed for the first 1,000 consecutive minimally-invasive knees (820 patients) performed by a single surgeon with a minimum 2 year post-operative period. All patients were operated using the mid-vastus approach, with a mean incision length of 10 cm (range, 8 to 13 cm). Nine patients were lost prior to 2 year follow-up, leaving 990 knees (811 patients) in this report with annual follow-up. After determining overall results, data was stratified into 100-knee groups to determine whether complication rates changed over time. Finally, complication rates were compared to a matched group of 50 knees operated by the same surgeon.

Results: There were a total of 45 clinical complications (4.5%), including 20 (2.0%) manipulations under anesthesia, 12 (1.2%) arthroscopies for painful crepitus, 4 (0.4%) component changes, and 3 (0.3%) spacer changes. There were 3 (0.3%) impending radiographic failures. Stratification of results showed a complication rate of 6% over the first 200 knees, and 1% over the subsequent 800 knees. In comparison, the matched group had a complication rate of 4% over mean follow-up of 3 years (range, 2 to 4).

Conclusion: This large series with minimum two year follow-up describes many of the long-term complications of this technique. Additionally, this large series suggests that high volume knee surgeons may require as many as 200 minimally invasive arthroplasties before achieving optimum proficiency with this technique. Nonetheless, comparison to a matched group suggests that even with this learning curve, complication rates need not increase markedly during this period if surgeons remain attentive to the potential complications associated with minimally invasive techniques.