Douglas Naudie

Survivorship of the High Tibial Valgus Osteotomy A 10-to 22-Year Followup Study

The results of 106 high tibial valgus osteotomies in 85 patients were evaluated after a minimum 10-year followup to determine survivorship, complications, and risk factors associated with failure. Using Kaplan-Meier survivorship analysis, 73% of patients at 5 years, 51% of patients at 10 years, 39% at 15 years, and 30% at 20 years after high tibial osteotomy had not required conversion of the high tibial osteotomy to a total knee arthroplasty. Univariate Cox regression analysis of risk factors showed that age older than 50 years, previous arthroscopic debridement, presence of a lateral tibial thrust, preoperative knee flexion less than 120 degrees, insufficient valgus correction, and development of delayed union or nonunion were significantly associated with probability of early failure. Multivariate Cox regression analysis showed that a body mass index of less than 25 kg/m2, presence of a lateral tibial thrust, and development of delayed union or nonunion were significantly associated with probability of early failure. Using recursive partitioning analysis of risk factors with the Wilcoxon test, a subset of patients who were younger than 50 years of age and who had preoperative knee flexion greater than 120 degrees had a probability of survival after high tibial osteotomy approaching 95% at 5 years, 80% at 10 years, and 60% at 15 years. These results suggest that survival of high tibial osteotomy can be improved through careful patient selection and surgical technique.

Wear and Osteolysis Around Total Knee Arthroplasty

Osteolysis induced by wear debris of ultra-high-molecular-weight polyethylene has emerged as a significant problem after total knee arthroplasty. The generation of polyethylene wear and the development of osteolysis around total knee arthroplasty are caused by a combination of patient, implant, and surgical factors. Activity level over time may be the most important patient factor affecting the loads placed on a total knee replacement, but it is the most difficult to manage. Multiple factors related to the manufacturing of the polyethylene implant influence the extent of wear, and surgeons should be cautious in considering enhanced polyethylenes pending results of further investigations. The optimal design of the articular bearing surface remains controversial but needs to be considered with respect to the stresses imparted on component-bone and modular tibial backside interfaces. Surgical factors, including restoration of alignment and ligament balance, are important for long-term durability of the implant. Methods of measuring the wear of total knee implants are still evolving. Thus, when confronted with a worn total knee implant and developing osteolysis, the surgeon should consider each of these factors in selecting the best management option to eliminate the source of debris and minimize the potential for wear and osteolysis following revision.

Opening Wedge High Tibial Osteotomy for Symptomatic Hyperextension-Varus Thrust

Background The purpose of this study was to assess the functional outcome of opening wedge high tibial osteotomy (HTO) in a young, active group of patients with instability rather than osteoarthritis. Methods The results of 17 opening wedge HTOs in 16 patients with a symptomatic hyperextension-varus thrust were evaluated. Functional results were evaluated according to the activity scoring system of Tegner and Lysholm and using a 5-point visual analogue scale to assess change in knee stability and satisfaction. Radiographs were analyzed to determine changes in femorotibial and mechanical axis alignment, tibial slope, and patellar height. Results Patients were followed for a mean of 56 months. All patients had an increase in their activity score postoperatively. Nine patients rated their symptoms as significantly better and seven as somewhat better. All but one were satisfied with the surgery. Femorotibial axis alignment was changed to a mean of 6 ° valgus, mechanical axis alignment was corrected to a mean of 46% toward the lateral compartment, posterior tibial slope was increased a mean of 8 °, and the ratio of patellar height was decreased a mean of 0.17. Conclusion Opening wedge HTO can produce good functional and radiographic results in selected patients with a symptomatic thrust.

The John Insall Award: Gender-specific Total Knee Replacement: Prospectively Collected Clinical Outcomes

AbstractGender-specific total knee replacement design is a recent and debated topic. We determined the survivorship and clinical outcomes of a large primary total knee arthroplasty cohort, specifically assessing any differences between gender groups. A consecutive cohort of 3817 patients with 5279 primary total knee replacements (3100 female, 2179 male) with a minimum of 2 years followup were evaluated. Preoperative, latest, and change in clinical outcome scores (WOMAC, SF-12, KSCRS) were compared. While men had higher raw scores preoperatively, women had greater improvement in all WOMAC domains including pain (29.87 versus 27.3), joint stiffness (26.78 versus 24.26), function (27.21 versus 23.09), and total scores (28.35 versus 25.09). There were no gender differences in improvements of the SF-12 physical scores. Men had greater improvement in Knee Society function (22.1 versus 18.63) and total scores (70.01 versus 65.42), but not the Knee Society knee score (47.83 versus 46.64). Revision rates were 10.2% for men and 8% for women. Women demonstrated greater implant survivorship, greater improvement in WOMAC scores, equal improvements in SF-12 scores, and less improvement in only the Knee Society function and total scores. The data refute the hypothesis of inferior clinical outcome for women following total knee arthroplasty when using standard components. Level of Evidence: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Radiographic methods for the assessment of polyethylene wear after total hip arthroplasty.

All wear-measurement techniques assess femoral head penetration and therefore cannot distinguish between true polyethylene wear and bedding-in. Multiple wear measurements that are made at different time-intervals after bedding-in has occurred are required to determine the true wear rate. Computer-assisted edge-detection techniques offer improved accuracy and precision compared with manual techniques and appear to be ideally suited for the retrospective and prospective examination of large groups of patients with intermediate to long-term radiographic follow-up (more than five years). While radiostereometric analysis offers improved accuracy and precision compared with computer-assisted edge-detection techniques, widescale clinical application is limited because of its relative expense, the required expertise, and the fact that it can only be used in a prospective fashion.

Medial unicompartmental knee arthroplasty with the Miller-Galante prosthesis.

BACKGROUND Unicompartmental knee arthroplasty has become a popular treatment alternative for osteoarthritis that is confined to the medial part of the knee. Excellent intermediate-term results recently have been reported in association with the Miller-Galante unicompartmental implant. The purpose of the present study was to report on our longer-term experience with the Miller-Galante medial unicompartmental knee implant. METHODS We evaluated the results of 113 medial unicompartmental knee arthroplasties that had been performed with use of the Miller-Galante implant in eighty-four patients between 1989 and 2000. The mean age of the patients at the time of surgery was sixty-eight years. Forty-five patients were men, and thirty-nine were women. Thirteen patients (sixteen knees) died at a mean of seven years after the index arthroplasty. No patient was lost to follow-up. The remaining seventy-one patients (ninety-seven knees) were followed for a mean of ten years and were evaluated with use of the Knee Society clinical and radiographic rating system. RESULTS Eleven knees were revised at a mean of four years after the index procedure. The mean Knee Society knee and function scores for the sixty-one patients (eighty-six knees) who were living and who had not had a revision improved from 48 and 53 points preoperatively to 93 and 80 points at the time of the most recent evaluation. The five and ten-year rates of survival were 94% and 90%, respectively, with revision to tricompartmental knee arthroplasty as the end point and 93% and 86%, respectively, with revision or radiographic loosening as the end point. CONCLUSIONS The Miller-Galante medial unicompartmental knee arthroplasty provided excellent pain relief and restoration of function in carefully selected patients and demonstrated durable implant survival at ten years.

2008 John Charnley Award: Metal Ion Levels After Metal-on-Metal Total Hip Arthroplasty: A Randomized Trial

AbstractMetal-on-metal bearing total hip arthroplasty is performed more commonly than in the past. There may be manufacturing differences such as clearance, roughness, metallurgy, and head size that affect performance. In a prospective, randomized trial, we compared 2-year postoperative ion levels for a 28-mm metal-on-polyethylene bearing with 28-mm and 36-mm metal-on-metal bearings. We measured serum, erythrocyte, and urine ion levels. We observed no difference in the ion levels for the 28-mm and 36-mm metal-on-metal bearings. The ion levels in these patients were lower than reported for most other metal-on-metal bearings. Although both erythrocyte and serum cobalt increased, erythrocyte chromium and erythrocyte titanium did not increase despite a four- to sixfold serum chromium and a three- to fourfold serum titanium increase. This may represent a threshold level for serum chromium and serum titanium below which erythrocytes are not affected. Level of Evidence: Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Does morbid obesity affect the outcome of total hip replacement?: AN ANALYSIS OF 3290 THRS

We evaluated the outcome of primary total hip replacement (THR) in 3290 patients with the primary diagnosis of osteoarthritis at a minimum follow-up of two years. They were stratified into categories of body mass index (BMI) based on the World Health Organisation classification of obesity. Statistical analysis was carried out to determine if there was a difference in the post-operative Western Ontario and McMaster Universities osteoarthritis index, the Harris hip score and the Short-Form-12 outcome based on the BMI. While the pre- and post-operative scores were lower for the group classified as morbidly obese, the overall change in outcome scores suggested an equal if not greater improvement compared with the non-morbidly obese patients. The overall survivorship and rate of complications were similar in the BMI groups although there was a slightly higher rate of revision for sepsis in the morbidly obese group. Morbid obesity does not affect the post-operative outcome after THR, with the possible exception of a marginally increased rate of infection. Therefore withholding surgery based on the BMI is not justified.

Computed Tomography in the Assessment of Periacetabular Osteolysis

BACKGROUND Computed tomography recently has been proposed as an accurate method for diagnosing periacetabular osteolytic lesions. Several investigators have attempted to validate the accuracy of this technique, but they employed cadaveric and animal models, which cannot replicate the adaptive changes that occur over time in vivo. This study was performed to determine the accuracy of computed tomography in identifying and measuring periacetabular osteolytic lesions in hemipelves retrieved at autopsies of individuals with a previously well-functioning total hip prosthesis. METHODS We evaluated nine hemipelves, retrieved at autopsy, that contained a cementless porous-coated acetabular component. The fresh specimens were examined with conventional radiographs and computed tomography and then were embedded and sectioned into 1.5-mm slices for evaluation with slab radiographs. Anteroposterior and iliac oblique plain radiographs as well as axial, coronal, and sagittal computed tomography scans were reviewed to determine the presence and location of any periacetabular osteolytic lesions. These results were then compared with those identified on the slab radiographs. Lesion volume was calculated from computed tomography scans with use of post-processing software. RESULTS A total of twenty-three periacetabular osteolytic lesions were identified on the slab radiographs of the nine hemipelves. The plain radiographs identified twelve (52%) of the twenty-three lesions, and the computed tomography scans identified twenty (87%) of the twenty-three lesions. Three medial wall perforations were identified on the computed tomography scans but were not detected on the plain radiographs. Computed tomography was accurate in measuring the volume of the osteolytic lesions (r(2) = 0.997) but tended to overestimate the volumes measured on the slab radiographs. Periacetabular osteolytic lesions appeared on the computed tomography scans and slab radiographs as areas devoid of trabecular bone that were delineated by a sclerotic border and communicated with the joint space. CONCLUSIONS In this autopsy model, computed tomography was an accurate method for detecting the location and measuring the volume of periacetabular osteolytic lesions.

Diagnostic features of pelvic osteolysis on computed tomography: the importance of communication pathways.

BACKGROUND Progressive periacetabular osteolysis following total hip arthroplasty may require revision surgery. The purpose of this study was to use computed tomography scans of hemipelves retrieved at autopsy from patients who had had a total hip arthroplasty, to define the radiographic characteristics that differentiate clinically important osteolytic lesions from osteoarthritic bone cysts. METHODS We analyzed forty-four hemipelves that had been retrieved at autopsy at a mean of eight years after a total hip arthroplasty with an uncemented acetabular component. Computed tomography images were analyzed to identify the location, volume, and presence of cortical erosion and/or communication pathways with the joint space for all periacetabular bone defects. Lesions that were not present on preoperative or immediate postoperative plain radiographs were defined as new lesions. These new lesions were compared with those that were present on preoperative or immediate postoperative plain radiographs, which were defined as preexisting lesions. RESULTS Forty-six lesions were identified on computed tomography, and sixteen of them were preexisting lesions. The mean volume of the preexisting lesions was 1.5 +/- 1.5 cm(3), which was significantly smaller than the mean volume of 5.6 +/- 11.4 cm(3) of the thirty new lesions (p = 0.034). Twenty-eight of the thirty new lesions had a clear communication pathway with the joint space, while thirteen of the sixteen preexisting lesions demonstrated no communication pathway. New lesions were significantly more likely to communicate with the joint space than were preexisting lesions (p < 0.001). Cortical erosion was seen in sixteen of the thirty new lesions; none of the sixteen preexisting lesions exhibited cortical erosion (p < 0.001). CONCLUSIONS The most important difference between osteolytic lesions and preexisting bone defects was the presence of a communication pathway to the joint space. Lesions that did not have an identifiable communication to the joint space were smaller and were not associated with cortical erosion. Lesions with communication to the joint through multiple pathways or through a central dome hole were larger and more likely to be associated with cortical erosion.