Primary total hip replacement in childhood, adolescence and young patients: quality and outcome of clinical studies.

OBJECTIVE: The present meta-analysis illustrates relevant information about hip replacement in young patients that has been published during the past 3 decades. MATERIAL AND METHODS: Based on a MedLine literature review a total of 95 studies were evaluated. Parameters for evaluation of study quality and outcome were implant survival rates (ISR),number of patients, indications, follow-up, surgical approaches and number of surgeons. RESULTS: Most studies consider patient numbers <50. In 33 studies one implant system was applied compared to 65 studies in which more than one system was used. Most studies include different surgical approaches. 20% of all studies contained neither the number of surgeons,nor the type of surgical approach. The overall ISR could be evaluated in 67 studies. Sufficient data about the ISR of stem and/or sockets were available in 50 papers. CONCLUSIONS: Most published studies analyzed inhomogeneous study populations; study variables vary as do the implants used for treatment.

Importance of vitamin D in hospital-based fracture care pathways.

OBJECTIVES: This project was developed to identify ways to support hospital-based improvements for the identification and management of osteoporosis following treatment of a fragility fracture. DESIGN: This is a retrospective review of medical records of sets of consecutive patients who were admitted for surgical treatment of fragility fracture following introduction of several versions of admission and discharge care pathways. Effectiveness of the admission pathway was defined as % subjects with measurement of serum 25- hydroxyvitamin D (25(OH)D) during hospitalization; effectiveness of the discharge pathway was defined as % subjects with documentation of instructions for calcium and/or vitamin D supplementation. SETTING: This study reviewed medical records of patients admitted to hospital for surgical treatment of a fragility fracture. PARTICIPANTS: Medical records were evaluated for 98 patients older than 50-years who were admitted with a fragility fracture of the hip or femur. MEASUREMENTS: Medical records were reviewed for the % subjects with documentation of an in-hospital order for serum 25(OH)D and with documentation of instructions to patients upon discharge concerning calcium and vitamin D intake. Median value of serum 25(OH)D was calculated. RESULTS: In accordance with the admission pathway, serum 25(OH)D was measured in 37% (36/98). The median 25(OH)D level was 19.5 ng/mL; 78% were vitamin D insufficient [serum 25(OH)D < or = 32 ng/mL] and 58% were vitamin D deficient [serum 25(OH)D < or = 20 ng/mL]. In accordance with the discharge pathway, 74% (71/96) were discharged on calcium and/or vitamin D. CONCLUSION: The high prevalence of vitamin D insufficiency (78%) observed in this study affirms the importance of incorporating vitamin D supplementation in hospital-based fracture care pathways. The discharge pathway was more effective than the newer admission pathway, a finding attributable to effects of familiarity, retraining, and introduction of computer-prompts. These evolving pathways represent a much-needed paradigm shift in the care of fragility fracture patients.

Correlation of plain radiographic indices of the hip with quantitative bone mineral density.

UNLABELLED: Radiographic parameters of the hip can be useful as an indication of bone mineral density at the femoral neck. Measurements available from routine hip radiographs were correlated with DXA values. Although radiographs are not a test for osteoporosis, measurements of cortical thickness provide information useful for referral for osteoporosis assessment. INTRODUCTION: Plain hip radiographs are widely used for evaluation of hip pathology in osteoarthritis. A purpose of this study was to determine whether there are relationships between radiographic parameters of bone structure and bone mineral density T-scores, as assessed by dual energy x-ray absorptiometry (DXA). METHODS: Pre-operative radiographs of 32 postmenopausal, osteoarthritic women undergoing hip arthroplasty were evaluated. Radiographic parameters including the Singh index, Dorr classification, canal-to-calcar ratio, and cortical thickness indices (CTI) were measured and compared with T-score, serum 25 hydroxyvitamin D levels, body mass index (BMI), and body weight. RESULTS: The T-score at the femoral neck for type C bone was significantly lower than that of type A (p = 0.041). The CTIs were correlated positively with T-scores for anteroposterior radiographs (r = 0.5814, p = 0.0005), and for lateral radiographs (r = 0.571, p = 0.0006). A threshold for lateral CTI set at a value of < or =0.40 results in sensitivity of 0.85 and specificity of 0.79 to segregate the osteoporotic and non-osteoporotic patients. CONCLUSION: Femurs with small radiographic cortical thickness indices had lower T-scores. Finding a radiographic hip cortical thickness index (LAT) with a value of < or =0.40 should be an alert for referral for osteoporosis evaluation and bone mineral density testing.

Effect of mechanical perturbation on the release of PGE(2) by macrophages in vitro.

Macrophages play numerous roles in both physiologic and pathologic processes. Along with fibroblasts, they comprise the synovial tissue that forms the lining of musculoskeletal joint capsules and bursae, and they often envelop implants. During the process of phagocytosing prosthesis-related particles, macrophages in peri-implant tissue release inflammatory mediators. Little is known, however, about the response of these cells to mechanical perturbation, which often is a component of the physical environment of the cell. Mouse peritoneal macrophages were grown on a flexible membrane in vitro and a dynamic 1-Hz spatially uniform sinusoidal strain pattern imparted to the elastomeric substrate. The effect of mechanical strain on prostaglandin (PG) E(2) release was evaluated using cells that were activated by lipopolysaccharide (LPS) as well as by those that were not. The results are compared with the levels of PGE(2) stimulated by metallic particles. Strain magnitudes of 4 and 8% applied for 1 h resulted in almost a twofold increase in the release of PGE(2) from LPS-stimulated cells (p < 0.05) and nonstimulated macrophages (p < 0.07), compared with nonperturbated controls. No release was elicited by a challenge of metal particles. These findings demonstrate for the first time an effect of mechanical force on the release of an inflammatory mediator by macrophages. This response may help to explain the macrophage-mediated processes underlying the osteolysis associated with loose prostheses in bone and suggests a mechanism for the inflammation of synovial tissues by excessive mechanical strain.

Alternatives to total hip arthroplasty in osteonecrosis of the femoral head.

While THA can provide excellent relief and functional return for patients with osteonecrosis, it is important to establish an early and accurate diagnosis and develop a treatment paradigm to seek surgical alternatives to THA for treatment of this condition.

Transmission electron microscopy of intracellular particles of polyethylene from joint replacement prostheses: size distribution and cellular response.

The objectives of this transmission electron microscopy study of peri-implant tissues retrieved at revision arthroplasty were to (1) determine the size distribution of intracellular polyethylene particles, and (2) assess the cellular response to phagocytosed polyethylene particles as revealed by the condition of the cellular organelles. The frequency distributions of intracellular polyethylene particle sizes for 15 cases of total hip replacement showed that more than 75% of the particles had lengths of less than 0.5 microm. More than 90% of the particles were less than 1.0 microm in size. In comparison, the frequency distribution for the particles in cellscomprising tissue retrieved from three total knee replacement prostheses showed that only 43% of the particles were less than 0.5 microm in length and 72% were less than 1 microm in size. There was no statistically significant difference in the mean particle length between the specimens from the hip and knee patients. The majority of the cells containing polyethylene were without signs of degeneration. The cytoplasmic and nuclear membranes were intact. Several electron lucent voids which once contained polyethylene particles were seen surrounded by several healthy appearing mitochondria, which displayed sharp membranes and intact cristae. There were no signs of a cytotoxic response to polyethylene at the ultrastructural level.

Cost and effectiveness of routine pathological examination of operative specimens obtained during primary total hip and knee replacement in patients with osteoarthritis.

BACKGROUND: The challenge of cost-efficiency is maintaining the quality of medical care while reducing costs and eliminating unnecessary practices. The purpose of this investigation was to evaluate the cost and effectiveness of routine pathological examination of surgical specimens from patients undergoing primary total hip or knee replacement for the treatment of osteoarthritis. METHODS: Effectiveness was assessed by comparing clinical and pathological diagnoses associated with 1,234 consecutive primary total joint replacements (471 hip and 763 knee replacements) performed between 1992 and 1995 in one hospital in patients with the clinical diagnosis of osteoarthritis. Clinical and pathological diagnoses were considered concordant if they agreed, discrepant if they differed without a resultant change in patient management, and discordant if they differed with a resultant change in patient management. Cost identification was performed by determining charges, reimbursement, and costs in 1998-adjusted American dollars for both total hip and total knee replacement. The cost per health-effect was determined by calculating the cost per discrepant and discordant diagnosis. RESULTS: The prevalence of concordant diagnoses was 97.6 percent (1,205 of 1,234) (95 percent confidence interval, 96.6 to 98.4 percent), the prevalence of discrepant diagnoses was 2.3 percent (twenty-eight of 1,234) (95 percent confidence interval, 1.4 to 3.1 percent), and the prevalence of discordant diagnoses was 0.1 percent (one of 1,234) (95 percent confidence interval, 0.1 to 0.3 percent). The cost per discrepant diagnosis was $4,383, and the cost per discordant diagnosis was $122,728. CONCLUSIONS: Routine pathological examination of surgical specimens from patients undergoing primary total hip or knee replacement because of the clinical diagnosis of osteoarthritis had limited cost-effectiveness at our hospital due to the low prevalence of findings that altered patient management.

Total knee arthroplasty with posterior cruciate retention in patients with rheumatoid arthritis.

The objective of the present study was to evaluate posterior cruciate ligament retention in total knee arthroplasty for patients with rheumatoid arthritis to determine long term ligamentuous stability. The study concerns an average 11-year followup (range, 10-13 years) of 52 patients (81 knees) with rheumatoid arthritis who had a total knee arthroplasty using a contemporary posterior cruciate retaining prosthesis. Particular attention was given to component survivorship and clinical stability. Fourteen patients (20 knees) died; none of these patients required revision surgery. No patients were lost to followup. Sixty-one knees in 38 patients were examined. In this group, the Knee Society knee score averaged 95 points (range, 63-100 points) and function score averaged 74 points (range, 0-100 points). Postoperative flexion averaged 112 degrees and extension averaged 0 degree. Four knees had 3 degrees asymptomatic hyperextension; one knee with 5 degrees hyperextension occasionally gave way. Five well aligned knees had between 6 degrees and 9 degrees varus or valgus laxity in extension, but no patient reported subjective instability. Two patients underwent revision surgery. One patient had a worn metal backed patella component replaced and the other patient had an open synovectomy for recurrent active rheumatoid synovitis. Thirteen-year survivorship based on need for revision surgery was 97% with the 95% confidence limits between 88% and 100%. There was no radiographic loosening or subsidence of prosthetic components. At 11-year followup, patients with rheumatoid arthritis whose knees were replaced with posterior cruciate retention prostheses experienced results equivalent to or better than those reported for patients with osteoarthritis at a similar followup. Late hyperextension and subsequent instability may be a concern in the second decade of followup.

Survivorship analysis of hips treated with core decompression for nontraumatic osteonecrosis of the femoral head.

We reviewed the long-term results of core decompression for the treatment of nontraumatic osteonecrosis of the femoral head, performed in thirty-four patients (fifty-four hips) between January 1, 1981, and June 30, 1995. Twenty patients (59 percent) had bilateral involvement. The mean age of the patients at the time of presentation was thirty-eight years (range, twenty-two to eighty-three years). The presumed risk factors were use of corticosteroids (thirty-seven hips), excessive intake of alcohol (eight hips), and use of adrenocorticotropic hormone for the treatment of multiple sclerosis (two hips); the remaining seven hips had idiopathic osteonecrosis. According to a modification of the classification system of Ficat and Arlet in combination with the system of Steinberg et al., thirteen hips were stage I (normal radiographs) preoperatively; seven, stage IIA sclerotic; sixteen, stage IIA cystic or sclerocystic; ten, stage IIB (transitional stage, with a crescent sign); and eight, stage III (collapse). The mean duration of follow-up after the core decompression was 120 months (range, twenty-four to 196 months). The result was considered successful if the patient was asymptomatic, with no progression of the disease, and unsuccessful if there was radiographic failure (progression to stage III [collapse]) or clinical failure (the need for a subsequent operation), or both. The Kaplan-Meier product-limit method was used to estimate clinical and radiographic survival. Overall, twenty-six hips (48 percent) had a satisfactory clinical result and twenty (37 percent) survived according to radiographic criteria. Radiographic or clinical failure, or both, were seen in four of the thirteen stage-I hips, none of the seven stage-IIA sclerotic hips, thirteen of the sixteen stage-IIA cystic or sclerocystic hips, nine of the ten stage-IIB hips, and all eight stage-III hips. On the basis of the Cox proportional-hazards regression model, significant predictors of overall failure included an advanced preoperative radiographic stage (p < 0.0001), a shorter duration of symptoms (p < 0.05), and use of corticosteroids (p < 0.05). No association was found between age, gender, excessive intake of alcohol, or renal transplantation and the overall outcome. Two patients (two hips; 4 percent) had a postoperative complication. One patient had a fracture of the femoral neck, and the other had a hematoma. Our findings suggest that core decompression is a safe and effective procedure for the treatment of stage-I or stage-IIA sclerotic disease. These data also demonstrate the importance of differentiating between stage-IIA sclerotic disease and stage-IIA cystic or sclerocystic disease. We believe that core decompression has a limited role in the operative management of patients who have evidence of cystic changes in the femoral head on plain radiographs.

Current concepts of total knee arthroplasty.

Total knee arthroplasty has become a reliable surgical procedure to treat painful degenerative arthritis. Pain relief and functional improvement is excellent and can allow patients to maintain an active lifestyle. Criteria for the type of prostheses selected should include diagnosis, age, functional level, severity of the disease, and patient expectations. Improved instrumentation, attention to surgical detail, including soft tissue balancing of the knee, and the use of polyethylene inserts greater than 8 mm have led to excellent long-term results and low failure rates. Recent improvements in revision total knee systems should significantly improve the long-term results of revision knee arthroplasty. The addition of modular implants has greatly increased the versatility of most systems and allows the surgeon to custom tailor the implant, contingent upon the amount of bony and ligamentous deficiency of the knee. The future goals of total knee arthroplasty include the development of knee systems that mimic normal joint kinematics with improved fixation and decreased polyethylene wear rates.

Total knee arthroplasty with the PFC system. Results at a minimum of ten years and survivorship analysis.

A consecutive series of 235 total knee arthroplasties using the PFC system was followed prospectively for at least ten years in 186 patients. The operation was for osteoarthritis in 150 knees, for rheumatoid arthritis in 83, and for Paget's disease and femoral osteonecrosis in one knee each. At the latest review 56 patients had died, five were too ill to assess and three could not be traced. The PFC knee replacement utilised was a non-conforming posterior-cruciate-retaining prosthesis with a polyethylene insert which is flat in the sagittal plane. The patella was resurfaced using a metal-backed component in 170 cases, but later in the series we used an all-polyethylene component in 22 knees; 43 patellae were not resurfaced. The survival without need for reoperation for any reason was 90% at ten years. Nineteen revisions were component-related due to failure of nine metal-backed patellae, nine polyethylene inserts, and one unresurfaced patella; two reoperations were for synovectomy (one for recurrent haemarthrosis and one for recurrent rheumatoid synovitis) and three were for metastatic joint infection. There were no revisions for aseptic loosening of femoral or tibial components, or the all-polyethylene patellar replacement. The PFC system provides good and predictable results in tricompartmental arthritis of the knee. Loosening appeared to be negligible, but there were wear-related problems in 8%. The change from a metal-backed patella and an increase in the contact area of the tibial insert should provide further improvement by minimising wear.

Unicompartmental knee arthroplasty in middle-aged patients: a 2- to 6-year follow-up evaluation.

Twenty-eight unicompartmental knee arthroplasties performed as an alternative to high tibial osteotomy or tricompartmental knee arthroplasty in patients under 60 years of age were reviewed after 2 to 6 years of follow-up. The patient's age at the time of operation averaged 52 years. Using the Knee Society Score, 90% were rated good or excellent results in terms of function and pain relief. The average flexion angle obtained was 124 degrees, and the average postoperative alignment was 4 degrees of anatomic valgus for varus deformities and 8 degrees for valgus deformities. The average activity level according to the Tegner and Lysholm score slightly improved (preoperative, 2.3; follow-up, 2.7 points). Of the 28 knees, 9 (32%) presented radiolucent lines about the tibial component and two had incomplete radiolucent lines at the bone-cement interface on the femoral side. There was no correlation between activity level and tibial radiolucent lines. Two revisions were performed because of loosening of the femoral component at the prosthesis-cement interface. One was converted to another unicompartmental arthroplasty and the other to a tricompartmental arthroplasty. One tibial component exhibited an asymptomatic slowly progressive radiolucency. Unicompartmental knee arthroplasty in middle-aged patients yields 2- to 6-year results competitive with osteotomy but inferior to tricompartmental arthroplasty in terms of revision. The specific prosthetic design used in this series appeared to be vulnerable to femoral component loosening possibly because of constrained tibial topography and smooth tapered femoral fixation lugs.

Identification of cell types responsible for bone resorption in rheumatoid arthritis and juvenile rheumatoid arthritis.

Focal resorption of bone at the bone-pannus interface is common in rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA) and can result in significant morbidity. However, the specific cellular and hormonal mechanisms involved in this process are not well established. We examined tissue sections from areas of bone erosion in patients with RA and JRA. Multinucleated cells (MNCs) were present in resorption lacunae in areas of calcified cartilage and in subchondral bone immediately adjacent to calcified cartilage, as previously described. mRNA for the calcitonin receptor (CTR) was localized to these MNCs in bone resorption lacunae, a finding that definitively identifies these cells as osteoclasts. These MNCs were also positive for tartrate-resistant acid phosphatase (TRAP) mRNA and TRAP enzymatic activity. Occasional mononuclear cells on the bone surface were also CTR positive. Mononuclear cells and MNCs not on bone surfaces were CTR negative. The restriction of CTR-positive cells to the surface of mineralized tissues suggests that bone and/or calcified cartilage provide signals that are critical for the differentiation of hematopoietic osteoclast precursors to fully differentiated osteoclasts. Some MNCs and mononuclear cells off bone and within invading tissues were TRAP positive. These cells likely represent the precursors of the CTR-TRAP-positive cells on bone. Parathyroid hormone receptor mRNA was present in cells with the phenotypic appearance of osteoblasts, in close proximity to MNCs, and in occasional cells within pannus tissue, but not in the MNCs in bone resorption lacunae. These findings demonstrate that osteoclasts within the rheumatoid lesion do not express parathyroid hormone receptor. In conclusion, the resorbing cells in RA exhibit a definitive osteoclastic phenotype, suggesting that pharmacological agents that inhibit osteoclast recruitment or activity are rational targets for blocking focal bone erosion in patients with RA and JRA.

In vivo anteroposterior femorotibial translation of total knee arthroplasty: a multicenter analysis.

A study was conducted to determine in vivo femorotibial contact patterns for subjects having a posterior cruciate retaining or posterior cruciate substituting total knee arthroplasty. Femorotibial contact of 72 subjects implanted with a total knee replacement, performed by five surgeons, was analyzed using video fluoroscopy. Thirty-one subjects were implanted with a posterior cruciate retaining total knee replacement with a flat polyethylene posterior lipped insert, 12 with a posterior cruciate retaining total knee replacement with a curved insert, and 29 with a posterior cruciate substituting total knee replacement. Each subject performed successive deep knee bends to maximum flexion. Video images at 0 degree, 30 degrees, 60 degrees, and 90 degrees flexion were downloaded onto a workstation computer. Femorotibial contact paths were determined for the medial and lateral condyles using an interactive model fitting technique. Femorotibial contact anterior to the tibial midline in the sagittal plane was denoted as positive and contact posterior was denoted as negative. Analysis of average femorotibial contact pathways of both posterior cruciate retaining designs revealed posterior femorotibial contact in full extension with anterior translation of femorotibial contact commonly observed in midflexion and terminal flexion. In posterior cruciate substituting designs, anterior femoral translation was seen medially at 30 degrees to 60 degrees flexion but rarely was observed laterally. Posterior femoral rollback laterally from full extension to 90 degrees flexion was seen in 100% of subjects implanted with a posterior cruciate substituting total knee replacement, versus 51.6% (posterior lipped polyethylene insert) and 58.3% (curved insert) of those with a posterior cruciate retaining total knee replacement. Data from this multicenter study are remarkably similar to previous fluoroscopy data from a single surgeon series, showing a lack of customary posterior femoral rollback in both posterior cruciate retaining designs, and conversely showing an average anterior femoral translation with knee flexion. Posterior femoral rollback, less than in normal knees, routinely was observed in posterior cruciate substituting total knee arthroplasty, attributed to engagement of the femoral component cam with the tibial post. The abnormal anterior femoral translation observed in posterior cruciate retaining total knee arthroplasty may be a factor in premature polyethylene wear observed in retrieval studies.

Press-fit condylar total knee arthroplasty. 5- to 9-year follow-up evaluation.

Between November 1984 and December 1987, 378 consecutive Press-Fit Condylar (PFC, Johnson & Johnson Professional, Raynham, MA) total knee arthroplasties were performed in 290 patients. The average age at surgery was 67 years (range, 22-91 years). The average follow-up period was 6.5 years (range, 5-9 years). Scoring was carried out according to the Knee Society scoring system. The average preoperative knee score was 28, and the average postoperative knee score was 88. The average preoperative functional knee score was 49, and the average postoperative functional knee score was 72. Ninety-five percent of the patients had no pain on level walking and were satisfied with their functional result. The average postoperative knee flexion was 110 degrees. No implant showed any evidence of radiographic loosening. There were 17 complications, all requiring reoperation. Complications included excessive wear of a metal-backed patella in 8 knees. If complications resulting from the earlier use of a metal-backed patella are eliminated, the overall complication rate is 2.9%, which is comparable to or lower than the rates for other total knee systems with similar follow-up periods.

Results of total elbow arthroplasty after excision of the radial head and synovectomy in patients who had rheumatoid arthritis.

We compared the results of twenty-three consecutive capitellocondylar total elbow arthroplasties in twenty-three patients in whom an excision of the radial head and synovectomy for rheumatoid arthritis had failed with those of twenty-three non-consecutive primary capitellocondylar total elbow arthroplasties in twenty-three patients who had rheumatoid arthritis. The two groups were matched for age, gender, duration of follow-up, side of the operation, type of prosthesis, and operative approach. The average duration of follow-up was four years (range, two to fourteen years). At the most recent follow-up examination, use of a 100-point rating system demonstrated an improvement from an average preoperative score of 21 points (range, 12 to 42 points) to an average postoperative score of 87 points (range, 17 to 97 points) for the group in whom an excision of the radial head and synovectomy had failed. The group that had primary arthroplasty demonstrated an improvement from an average preoperative score of 22 points (range, 7 to 42 points) to an average postoperative score of 94 points (range, 85 to 100 points). The group that had primary arthroplasty had a significantly greater improvement in terms of relief of pain (p < 0.05), functional status (p < 0.01), and the elbow-rating score (p < 0.03) than the other group. Four patients who had had failure of an excision of the radial head and synovectomy and none of those who had primary arthroplasty needed an additional operative procedure. Six of the patients who had had a failed excision and synovectomy and none of the patients who had primary arthroplasty had instability of the elbow components. We concluded that, although excision of the radial head and synovectomy is a conservative and effective method of treating a painful rheumatoid elbow, conversion to a capitellocondylar total elbow arthroplasty is more difficult after such an operation and the results at a minimum of two years are inferior to those for primary capitellocondylar total elbow arthroplasty.

Conversion of failed modern unicompartmental arthroplasty to total knee arthroplasty.

Between January 1983 and January 1991, 29 patients (31 knees) with a failed Robert Brigham metal-backed knee arthroplasty (Johnson & Johnson, Raynham, MA) underwent revision to a total knee arthroplasty (TKA). Twenty-five patients had osteoarthritis, three avascular necrosis, and one rheumatoid arthritis. The average patient age was 72.3 years (range, 49-88 years), and the average weight was 179 lb. (range, 112-242 lb.). The interval between the primary and secondary index procedures averaged 62 months (range, 7-106 months), and mean postrevision follow-up period was 45 months (range, 24-104 months). The primary mechanism of failure of the UKA was tibial polyethylene wear in 21 knees and opposite compartment progression of arthritis in 10 knees. Sixteen knees had particulate synovitis with dense metallic staining of the synovium. At revision, the posterior cruciate ligament was spared in 30 knees and substituted in 1 knee. Restoration of bony deficiency at revision required cancellous bone-graft for contained defects in seven knees, tibial wedges in four knees, and femoral wedges in two knees. No defects received structural allografts. The data suggest that failed, modern unicompartmental knee arthroplasty can successfully be converted to TKA. In most cases, the posterior cruciate ligament can be spared and bone defects corrected with simple wedges or cancellous grafts. Moreover, the results of revision of failed unicompartmental knee arthroplasty are superior to those of failed TKA and failed high tibial osteotomy and comparable to the authors' results of primary TKA with similar-length follow-up periods. Although these results are encouraging, longer-term follow-up evaluation is required to determine survivorship of these revision arthroplasties.

Revision total knee arthroplasty after failed unicompartmental knee arthroplasty or high tibial osteotomy.

A retrospective matched-pair comparative analysis was done between 30 total knee arthroplasties following failed high tibial osteotomies and 30 total knee arthroplasties following failed unicompartmental knee arthroplasties. The groups were matched according to age, gender, type of prosthesis, primary disease, and length of followup. A minimum followup of 2 years was required for inclusion in the study, and the average followup was 3.8 years (range, 2-9 years). The Knee Society Knee Score for the high tibial osteotomy group was significantly higher than that for the unicompartmental arthroplasty group. More osseous reconstructions were required in the unicompartmental revisions. Difficulty with exposure was not significantly greater in the osteotomy group. Rates of component loosening were not significantly different between the groups. A failed unicompartmental knee arthroplasty and a failed high tibial osteotomy can be revised successfully to a total knee arthroplasty. The results confirm that revisions after unicondylar arthroplasty and high tibial osteotomy are technically demanding. In this series, the results of total knee arthroplasty following unicompartmental knee arthroplasty approached but did not equal those obtained after high tibial osteotomy.