What can be learned from minimum 20-year followup studies of knee arthroplasty?

BACKGROUND: Long-term evaluation of knee arthroplasty should provide relevant information concerning the durability and performance of the implant and the procedure. Because most arthroplasties are performed in older patients, most long-term followup studies have been performed in elderly cohorts and have had low patient survivorship to final followup; the degree to which attrition from patient deaths over time in these studies might influence their results has been poorly characterized. QUESTIONS/PURPOSES: The purpose of this study was to examine the results at 20-year followup of two prospectively followed knee arthroplasty cohorts to determine the following: (1) Are there relevant differences among the two implant cohorts in terms of revision for aseptic causes (osteolysis, or loosening)? (2) How does patient death over the long followup interval influence the comparison, and do the comparisons remain valid despite the high attrition rates? METHODS: Two knee arthroplasty cohorts from a single orthopaedic practice were evaluated: a modular tibial tray (101 knees) and a rotating platform (119 knees) design. All patients were followed for a minimum of 20 years or until death (mean, 14.1 years; SD 5.0 years). Average age at surgery for both cohorts was >70 years. The indications for the two cohorts were identical (functionally limiting knee pain) and was surgeon-specific (each surgeon performed all surgeries in that cohort). Revision rates through a competing risks analysis for implants and survivorship curves for patients were evaluated. RESULTS: Both of these elderly cohorts showed excellent implant survivorship at 20 years followup with only small differences in revision rates (6% revision versus 0% revision for the modular tibial tray and rotating platform, respectively). However, attrition from patient deaths was substantial and overall patient survivorship to 20-year followup was only 26%. Patient survivorship was significantly higher in patients<65 years of age in both cohorts (54% versus 15%, p<0.001 modular tray cohort, and 52% versus 26%, p=0.002 rotating platform cohort). Furthermore, in the modular tray cohort, patients<65 years had significantly higher revision rates (15% versus 3%, p=0.0019). CONCLUSIONS: These two cohorts demonstrate the durability of knee arthroplasty in older patients (the vast majority older than 65 years). Unfortunately, few patients lived to 20-year followup, thus introducing bias into the analysis. These data may be useful as a reference for the design of future prospective studies, and consideration should be given to enrolling younger patients to have robust numbers of living patients at long-term followup. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Thirty-five-year results after Charnley total hip arthroplasty in patients less than fifty years old. A concise follow-up of previous reports.

We report the updated results for a previously described cohort of patients who were less than fifty years old at the time of the index Charnley total hip arthroplasty with cement. The original cohort consisted of ninety-three consecutive hips in sixty-nine patients. The patients were followed for a minimum of thirty-five years after surgery or until death. At the latest follow-up evaluation, there were forty-one total hip replacements (44%) in thirty-two living patients. Thirty-four (37%) of the ninety-three total hip replacements in the original cohort had been revised or removed. Twenty acetabular (22%) and seven femoral (8%) components had been revised for aseptic loosening. Since the twenty-five-year follow-up, the average six-minute-walk distance decreased from 395 m to 171 m, and this decrease correlated with increasing comorbidity. This study demonstrates the durability of cemented total hip replacements in a young patient population. Although 63% (fifty-nine) of the ninety-three original hip replacements were functioning at the latest follow-up or at the time of death, a significant decrease in activity level was seen over time (p < 0.001). Of the forty-one original implants in the patients who were alive at the time of the thirty-five-year follow-up, only 46% (nineteen) were retained.

Minimum 20-year follow-up results of revision total hip arthroplasty with improved cementing technique.

A consecutive, non-selective cohort of 83 (77 patients) cemented total hip arthroplasty revisions using contemporary cementing techniques was analyzed at a minimum of 20 years following the index procedure. No patients were lost to follow-up. The average age at revision was 62.4 years (23 to 89). Twenty-two hips (26.5%) had had a reoperation, eighteen (21.7%) for aseptic loosening, 3 (3.6%) for femoral prosthesis fracture and 1 (1.2%) for dislocation. The incidence of re-revision for aseptic femoral loosening was 7.5% and for aseptic acetabular loosening was 21.7%. These results confirm that cemented femoral revision using improved cementing techniques is a durable option in revision hip surgery. In contrast to this, THA revisions using a cemented acetabular component have been less durable at this length of follow-up.

Is hospital teaching status a key factor in hospital charge for children with hip fractures?: preliminary findings from KID database.

OBJECTIVE: Proximal femur fractures cause significant pain and economic cost among pediatric patients. The purposes of this study were (a) to evaluate the distribution by hospital type (teaching hospital vs non-teaching hospital) of U.S. pediatric patients aged 1-20 years who were hospitalized with a closed hip fracture and (b) to discern the mean hospital charge and hospital length of stay after employing propensity score to reduce selection bias. METHODS: The 2006 Healthcare Cost and Utilization Project (HCUP) Kids' Inpatient Database (KID) was queried for children aged up to 20 years that had principle diagnosis of hip fracture injury. Hip fractures were defined by International Classification of Diseases, 9th Revision, Clinical Modification codes 820.0, 820.2 and 820.8 under Section "Injury and Poisoning (800-999)" with principle internal fixation procedure codes 78.55, 79.15 and 79.35. Patient demographics and hospital status were presented and analyzed. Differences in mean hospital charge and hospital length of stay by hospital teaching status were assessed via two propensity score based methods. RESULTS: In total, 1,827 patients were nation-ally included for analysis: 1,392 (76.2%) were treated at a teaching hospital and 435 (23.8%) were treated at a non-teaching hospital. The average age of the patients was 12.88 years old in teaching hospitals vs 14.33 years old in nonteaching hospitals. The propensity score based adjustment method showed mean hospital charge was $34,779 in teaching hospitals and $32,891 in the non-teaching hospitals, but these differences were not significant (p=0.2940). Likewise, mean length of hospital stay was 4.1 days in teaching hospitals and 3.89 days in non-teaching hospitals, but these differences were also not significant (p=0.4220). CONCLUSIONS: Hospital teaching status did not affect length of stay or total hospital costs in children treated surgically for proximal femur fractures. Future research should be directed at identifying factors associated with variations in hospital charge and length of stay.

Cementless THA for the treatment of osteonecrosis at 10-year follow-up: have we improved compared to cemented THA?

Results of cementless THA for osteonecrosis were evaluated at a minimum of 10-year follow-up and compared to our previous report of cemented THA for osteonecrosis. Eighty cementless THAs in 66 patients with osteonecrosis were followed for a minimum of 10 years. Evaluation consisted of need for revision; radiographic evidence of loosening, wear and osteolysis; activity monitoring with an accelerometer; UCLA, Tegner, WOMAC, and Harris hip scores. Results were compared to 48 cemented THAs performed for osteonecrosis with comparable follow-up. At a minimum of 10 years, 10 hips required reoperation. Loosening and revision for loosening were significantly lower in the cementless group compared to the cemented historical control. Cementless fixation in THAs for osteonecrosis demonstrated durable results with bearing surface wear being the major long-term problem.

Disparity in preoperative patient factors between insurance types in total joint arthroplasty.

Equity in health care has become a focal point of debate. However, the disparity between insurance payer types in total joint arthroplasty is poorly defined. The authors identified 1312 consecutive patients who underwent elective primary total hip or knee arthroplasty with available preoperative Short Form 36 and Western Ontario and McMaster University Osteoarthritis Index surveys and stratified them into groups based on insurance type (Iowa Care [a state-run insurance program for patients who are indigent], Medicare, Medicaid, or private insurance) to compare demographics, access to care, and functional data. Significance was a P value less than .05 after a Turkey-Kramer adjustment for multiple comparisons. A multivariate analysis identified independent predictors of Short Form 36 and Western Ontario and McMaster University Osteoarthritis Index preoperative functional status. Few differences existed between patients with Iowa Care and Medicaid, but both groups had significantly lower Short Form 36 and Western Ontario and McMaster University Osteoarthritis Index scores across every category compared with patients with Medicare or private insurance (P<.05 for each comparison). In addition, patients with Iowa Care and Medicaid had a higher incidence of current smoking and higher mean body mass index and traveled an average of 29 to 30 miles farther for access to care (P<.05 for each comparison). Payer type was an independent predictor of preoperative Short Form 36 and Western Ontario and McMaster University Osteoarthritis Index functional scores in the multivariate analysis (P<.02). Significant differences exist between payer types in total joint arthroplasty. Further research is necessary to better inform health policy decisions.

Revision with cementless acetabular components: a concise follow-up, at a minimum of twenty years, of previous reports.

UNLABELLED: The purpose of the present study was to analyze the longer-term results for a previously reported cohort of patients who were managed with cementless acetabular fixation at the time of revision arthroplasty. Sixty-one consecutive revision total hip arthroplasties were performed in fifty-five patients with use of a cementless acetabular component and screw-augmented fixation. This series was evaluated at minimum of twenty years. Twelve patients (fourteen hips) were living at twenty years. In this group of sixty-one arthroplasties, there were nineteen revisions in fourteen hips (22.9%) during the follow-up period, but no revisions were performed because of loosening of the acetabular component and no additional cups had loosened since the time of the last report at a minimum of ten years. Two components had previously been reported as loose and had migrated, but neither had been revised at the time of the latest follow-up. The minimum twenty-year follow-up of these cementless acetabular components demonstrated durable long-term fixation. The survival rate was 100% with revision of the shell because of aseptic loosening as the end point and 97.7% (95% confidence interval, ± 8.8%) with radiographic evidence of loosening as the end point. The authors continue to use cementless acetabular fixation with screw augmentation for most revision total hip arthroplasty procedures. LEVEL OF EVIDENCE: Therapeutic Level IV.

Disparity in total joint arthroplasty patient comorbidities, demographics, and postoperative outcomes based on insurance payer type.

Little is known about how patient characteristics differ between insurance types. We reviewed 293 consecutive primary total joint arthroplasty patients with 12-month follow-up and stratified them based on insurance type. As compared with patients with either Medicare or private insurance, Medicaid patients traveled an extra 160 to 170 miles for access to care, both Iowa Care and Medicaid were more than 3 times more likely to be current smokers, and both Iowa Care and Medicaid had lower preoperative and 12-month postoperative 36-Item Short Form Health Survey and WOMAC outcomes scores. Payer type was a significant predictor of 36-Item Short Form Health Survey physical function at final follow-up in a multivariate analysis. Significant disparities exist between patients with different insurance payer types in total joint arthroplasty, and further research into these differences is necessary.

Primary cementless acetabular fixation at a minimum of twenty years of follow-up: a concise update of a previous report.

The purpose of the present study was to analyze the longer-term results for a previously reported cohort of patients with cementless acetabular fixation and to compare the results with those for historical controls with cement fixation and a comparable follow-up period. One hundred and twenty consecutive nonselected total hip arthroplasties were performed in 108 patients with use of a cementless acetabular component. This series was evaluated at a minimum of twenty years of follow-up and was compared with 330 consecutive hip arthroplasties that had been performed by the same surgeon with use of cemented acetabular components and had been followed for a comparable period of time. Thirty-nine patients (forty-two hips) in the cementless fixation group were living at twenty years of follow-up. In the group of 120 hips with cementless acetabular fixation, twenty-two hips (18.3%) were revised during the follow-up period, but only one hip (0.8%) was revised because of loosening of the acetabular component, with no additional cup loosening since the previous report at thirteen to fifteen years of follow-up. In the group with cemented acetabular fixation with comparable follow-up, thirty-two hips (10%) were revised overall and eighteen hips (6%) were revised because of acetabular loosening. An additional twenty-five hips (8%) had acetabular cups that were loose on radiographs but had not undergone revision. At a minimum of twenty years of follow-up, cementless acetabular components provided superior long-term fixation compared with cemented components but the overall rates of acetabular revision for mechanical reasons were comparable.

Cementless acetabular fixation in patients 50 years and younger at 10 to 18 years of follow-up.

The purpose of the study was to evaluate the 10- to 18-year follow-up of cementless acetabular fixation in patients 50 years and younger. We retrospectively reviewed a consecutive group of 118 patients (144 hips) in whom primary total hip arthroplasty had been performed by 2 surgeons using a cementless acetabular component. Two (1.4%) cementless acetabular components were revised because of aseptic loosening. Twenty-four hips (16.7%) were revised for any mechanical failure of the acetabular component mostly related to acetabular liner wear and osteolysis. The average linear wear rate was 0.19 mm per year, which was higher than our previous reports with cemented acetabular fixation. The fiber mesh ingrowth surface of the cementless acetabular component in this study was superior to cemented acetabular components in terms of fixation. However, the high rates of wear and osteolysis have led to poor overall acetabular component construct survivorship.

Demographic and comorbid disparities based on payer type in a total joint arthroplasty cohort: implications in a changing health care arena.

INTRODUCTION: The purpose of this study was to compare differences in demographic, functional, access to care, and comorbidity data between a Medicaid and Iowa Care (state Medicaid) insured patient cohort and Medicare and a Commercial Payer patient cohort undergoing lower extremity total joint arthroplasty (TJA). MATERIAL & METHODS: A retrospective review of 874 primary TKAs and THAs by a single surgeon at an academic institution between January, 2004 and June, 2008 was performed. Data on the primary insurance payer was used to stratify the cohort into two groups; Medicaid and Iowa Care (state Medicaid) insured and Medicare and commercial payer. Demographic, functional, access to care, and comorbidity data obtained from a standard preoperative survey were compared. RESULTS: Of 874 primary TKAs and THAs, 18.3 % of patients were Medicaid and Iowa Care insured, while 81.7 % were insured by Medicare and commercial payer. Average age was 53.7 and 62.3 respectively, while average BMI was 35.2 and 32.9 respectively. The Medicaid and Iowa Care group was found to be 3 times more likely to smoke tobacco (25.2% v. 8.3%). Preoperative WOMAC Function scores were 33.9 and 46.8, respectively. Self reported diabetes was used as a general surrogate for health comorbidities and occurred in 12.3 % and 11.5%, respectively. Distance traveled was used as a general surrogate for access to care with averages of 92.5 miles and 62.8 miles, respectively. CONCLUSION: The Medicaid and Iowa Care (state Medicaid) group had significantly higher rates of smoking, were significantly younger, and had significantly lower WOMAC scores (p<0.05) preoperatively. BMI comparison showed a trend to greater obesity in the Medicaid and Iowa Care cohort (p=0.056). Diabetes rates were comparable between the two cohorts. Medicaid and Iowa Care patients traveled 29.7 miles farther, suggesting they had less access to local orthopaedic care. There are major differences in comorbidities and patient demographics between payer types.

Pediatric sports-related lower extremity fractures: hospital length of stay and charges: what is the role of the primary payer?

OBJECTIVE: The purposes of this study were (a) to evaluate the distribution by primary payer (public vs. private) of U.S. pediatric patients aged 5-18 years who were hospitalized with a sports-related lower extremity fracture and (b) to discern the adjusted mean hospital length of stay and mean charge per day by payer type. METHODS: Children who were aged 5 to 18 years and had diagnoses of lower extremity fracture and sports-related injury in the 2006 Healthcare Cost and Utilization Project Kids' Inpatient Database were included. Lower extremity fractures are defined as International Classification of Diseases, 9th Revision, Clinical Modification codes 820-829 under Section "Injury and Poisoning (800-999)," while sports-related external cause of injury codes (E-codes) are E886.0, E917.0, and E917.5. Differences in hospital length of stay and cost per day by payer type were assessed via adjusted least square mean analysis. RESULTS: The adjusted mean hospital length of stay was 20% higher for patients with a public payer (2.50 days) versus a private payer (2.08 days). The adjusted mean charge per day differed about 10% by payer type (public, US$7,900; private, US$8,794). CONCLUSIONS: Further research is required to identify factors that are associated with different length of stay and mean charge per day by payer type, and explore whether observed differences in hospital length of stay are the result of private payers enhancing patient care, thereby discharging patients in a more efficient manner.

Cemented rotating-platform total knee replacement: a concise follow-up, at a minimum of twenty years, of a previous report.

We previously evaluated 119 consecutive total knee arthroplasties performed by a single surgeon in eighty-six patients with use of the cemented LCS (low contact stress) mobile-bearing, rotating-platform system and an all-polyethylene patellar component. The average age of the patients at the time of surgery was seventy years. The patients were contacted as part of their routine follow-up and were asked to participate in this study. The purpose of the present study was to report the updated results at a minimum follow-up of twenty years. Twenty patients (twenty-six knees) were living, and one was lost to follow-up. Three knees required a reoperation (two for periprosthetic fractures and one for infection). No component was revised as a part of the reoperations. No knee required revision since the fifteen-year follow-up evaluation. Osteolysis was present in six knees compared with only three knees at the time of the fifteen-year follow-up. One knee had radiographic signs of femoral component loosening, which was associated with osteolysis. It occurred after the fifteen-year follow-up study. The average range of motion was from 1 degrees of extension to 105 degrees of flexion. The average clinical and functional Knee Society scores were 43 and 49 points, respectively, at the preoperative evaluation and 89 and 67 points at the time of the final follow-up. We concluded that the cemented LCS rotating-platform knee performed well, with durable clinical and radiographic results at a minimum follow-up of twenty years. However, the prevalence of osteolysis continues to increase with a longer duration of follow-up in these patients.

Survivorship of a Charnley total hip arthroplasty. A concise follow-up, at a minimum of thirty-five years, of previous reports.

The purpose of this study was to update the results, at a minimum of thirty-five years, in a single-surgeon series of primary Charnley total hip arthroplasties performed with cement. Twelve patients (fifteen hips) were alive, 249 patients (314 hips) had died, and one patient (one hip) had been lost to follow-up. Seven of the hips in the living patients had required at least one revision; 290 (88%) of the original group of total hip prostheses either continued to function or were in patients who had died. Since the time of a thirty-year study of this cohort, one hip that had previously been revised because of acetabular loosening required an additional revision because of acetabular loosening and two additional hips had evidence of radiographic loosening (of one acetabular and one femoral component). The survival rate with revision for any reason as the end point was 78%. This end result study should provide a benchmark for subsequent procedures and designs with the caveat that patient life expectancy will likely continue to increase and modern-design implants are being used in younger patients.

Cemented total hip replacement cable debris and acetabular construct durability.

BACKGROUND: Third-body wear can adversely affect the outcome of total hip arthroplasty by causing increased polyethylene wear, osteolysis, and component loosening. We hypothesized that there would be greater generation and migration of metal debris to the bearing surfaces in hips in which cobalt-chromium cables were used to reattach the osteotomized greater trochanter when compared with hips in which stainless steel wires were used. METHODS: Between June 1981 and December 1983, 196 consecutive total hip arthroplasties were performed with use of an Iowa stem and a titanium-backed cemented acetabular component, with cobalt-chromium cable trochanteric reattachment. After nineteen to twenty years of follow-up, the patients were evaluated with regard to the depth of head penetration into the polyethylene (as a surrogate for wear), osteolysis, loosening, and the need for revision. The results were compared with those for a series of 304 total hip arthroplasties that were performed by the same surgeon from January 1984 to December 1985 with use of the same components and the same surgical technique, but with stainless steel wire trochanteric reattachment. The two groups had a comparable nineteen to twenty-year follow-up. All living patients (fifty-nine hips in the cable group and ninety-two hips in the wire group) had minimum ten-year follow-up radiographs. RESULTS: The polyethylene wear rate was 0.101 mm/yr for the cable group and 0.082 mm/yr for the wire group (p = 0.039). For the living patients, the rate of revision of the acetabular component because of aseptic loosening was 37.3% (twenty-two hips) for the cable group and 20.7% (nineteen hips) for the wire group (p = 0.025). The rate of acetabular osteolysis was 44% (twenty-six hips) for the cable group and 26% (twenty-four hips) for the wire group (p = 0.022). Kaplan-Meier analysis with revision of the acetabular component because of aseptic loosening as the end point demonstrated survival rates of 73.7% +/- 9% and 83% +/- 7% for the cable and wire groups, respectively, at twenty years (p = 0.03). CONCLUSIONS: Because cable trochanteric attachment led to significantly greater polyethylene wear, osteolysis, acetabular loosening, and acetabular revision, presumably due to third-body metallic debris generation in this cemented total hip replacement construct, surgeons should be aware of the deleterious effects of third-body debris and avoid the use of potential debris generators in the total hip arthroplasty construct. If cable is used and fretting is recognized, especially with intra-articular migration of metallic material or nonunion of the greater trochanter, consideration should be given to cable removal.

Total hip arthroplasty with cement and use of a collared matte-finish femoral component: nineteen to twenty-year follow-up.

BACKGROUND: In the mid- to late 1970s, on the basis of laboratory and finite element data, many surgeons in the United States began using collared matte-finish femoral components and metal-backed acetabular components in their total hip arthroplasties. The purpose of this study was to evaluate the long-term results of the use of one such construct in arthroplasties performed by a single surgeon in a consecutive nonselected patient cohort. METHODS: Between January 1984 and December 1985, 273 patients underwent a total of 304 consecutive nonselected total hip arthroplasties with cement and use of the Iowa femoral component (which is collared, has a proximal cobra shape, and has a matte finish) and a metal-backed TiBac acetabular component performed by a single surgeon. At nineteen to twenty years postoperatively, only two patients (two hips) were lost to follow-up. For clinical evaluation, we attempted to interview all living patients and the families of the patients who had died to verify the status of the hip prosthesis or any revisions. Radiographic evaluation consisted of analysis for loosening and osteolysis as well as wear of the acetabular component. RESULTS: At the time of the nineteen to twenty-year follow-up, the rate of revision of the arthroplasty for any reason was 10.5% (thirty-two hips) for all patients and 25% (twenty-three hips) for living patients. The rate of revision due to aseptic femoral loosening was 2.6% (eight hips). There was radiographic evidence of loosening of the femoral component in fifteen hips (4.9%), including those that were revised, and femoral osteolysis was seen distal to the trochanters in twenty-two hips (7.2%). The rate of revision due to aseptic loosening of the acetabular component was 7.9% (twenty-four hips), and there was radiographic evidence of acetabular loosening in forty-two hips (13.8%), including those that were revised. CONCLUSIONS: This study demonstrates the durability of a cemented matte-finish collared femoral component at twenty years postoperatively, with a rate of revision due to aseptic loosening of 2.6%. The metal-backed acetabular component also performed well in many patients, with a 7.9% rate of revision due to aseptic loosening. However, in the living patients, the rate of loosening of the acetabular component, including cases revised because of aseptic loosening, was 30.4%.

Total hip arthroplasty with a cemented, polished, collared femoral stem and a cementless acetabular component. A follow-up study at a minimum of ten years.

BACKGROUND: Recent studies have suggested that cemented femoral components with a polished surface may provide superior long-term fixation when compared with femoral components with a roughened surface. The purpose of this study was to evaluate the results of total hip arthroplasty with a cemented femoral component with a polished surface finish and compare them with the results of total hip arthroplasty performed with a similar design of cemented femoral component with a rougher surface finish. METHODS: We retrospectively reviewed a consecutive group of 132 patients (149 hips) in whom primary total hip arthroplasty had been performed by one surgeon using a cemented collared femoral component with a polished (0.1-microm Ra) surface finish and a cementless acetabular component. Ninety-eight patients (115 hips) were followed for a minimum of ten years. We compared the survivorship of this prosthesis with that of a femoral component of similar design but with rougher surfaces (matte or grit-blasted). RESULTS: No polished stems were revised because of aseptic loosening or demonstrated radiographic evidence of loosening; however, eight hips (5.4%) with a polished stem demonstrated osteolysis distal to the greater or lesser tro-chanter. In contrast, six stems (2.0%) with a matte surface finish of 0.8-microm Ra were revised because of aseptic loosening, and an additional five stems were seen to be loose radiographically. Eleven stems (9.2%) with a grit-blasted surface finish of 2.1-microm Ra were revised because of aseptic loosening, and an additional four stems were seen to be loose radiographically. The difference in the prevalence of revision due to aseptic loosening between the group with the 0.1-microm Ra surface and the group with the 2.1-microm Ra surface was significant (p = 0.001), as was the difference between the prevalence of revision due to aseptic loosening between the group with the 0.8-microm Ra surface and the group with the 2.1-microm Ra surface (p = 0.001). No cups were revised because of aseptic loosening, and one hip had radiographic signs of acetabular loosening. CONCLUSIONS: This study demonstrated excellent durability of a prosthesis consisting of a cemented, collared, polished femoral component and a cementless acetabular component. While no hips were revised because of aseptic loosening, distal femoral osteolysis was observed in eight hips (5.4%), a higher prevalence than has been reported by others after similar durations of follow-up of tapered, collarless, polished femoral components.

Posttraumatic osteoarthritis: a first estimate of incidence, prevalence, and burden of disease.

Although posttraumatic osteoarthritis (OA) is a common and important entity in orthopedic practice, no data presently exist regarding its prevalence or its relative burden of disease. A population-based estimate was formulated, based on one large institution's experience in terms of its fraction of patients with OA presenting to lower-extremity adult reconstructive clinics with OA of posttraumatic origin. The relative proportion of these patients undergoing total joint replacement provided a basis for extrapolating institutional experience with posttraumatic OA to a populationwide estimate because the numbers of lower-extremity total joint arthroplasty procedures performed were reliably tabulated both within the institution and populationwide. By this methodology, approximately 12% of the overall prevalence of symptomatic OA is attributable to posttraumatic OA of the hip, knee, or ankle. This corresponds to approximately 5.6 million individuals in the United States being affected by posttraumatic OA sufficiently severe to have caused them to present for care by an orthopedic lower-extremity adult reconstructive surgeon. Further, based on the relative prevalence of OA versus rheumatoid arthritis, and their relative impacts as assessed by the SF-36 (Short-Form 36) lower-extremity physical composite scores, about 85.5% of the societal costs of arthritis are attributable to OA. The corresponding aggregate financial burden specifically of posttraumatic OA is Dollars 3.06 billion annually, or approximately 0.15% of the total U.S. health care direct cost outlay.

Results of Charnley total hip arthroplasty with use of improved femoral cementing techniques. a concise follow-up, at a minimum of twenty-five years, of a previous report.

UNLABELLED: The current study was performed to determine the status, at a minimum of twenty-five years, of a prospective, single-surgeon series of patients treated with primary Charnley total hip arthroplasty with a contemporary femoral cementing technique that included use of a distal cement plug and a retrograde cement-delivery system. Since our review at a minimum of twenty years postoperatively, two primary total hip prostheses were revised (one because of acetabular loosening, and one because of femoral loosening). Of the original cohort of 357 hips (320 patients), ten (2.8%) had revision of the femoral stem because of aseptic loosening. Forty-nine patients (fifty-two hips, 14.6%) who had been in the initial study group were still living at the time of the present review. Five hips (10%) in living patients had required a femoral revision because of aseptic loosening. Including those that were revised, eight femoral components (17%) in living patients were seen to be loose radiographically. Although this study demonstrates the remarkable durability of the femoral fixation obtained with the polished flatback Charnley prosthesis and the contemporary cementing technique, there was some deterioration of the results with time. These results provide a standard for comparison with cementless fixation after hips treated with that technique have been followed for a similar duration. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

The John Insall Award: unicompartmental knee replacement: a minimum twenty-one-year followup, end-result study.

UNLABELLED: We report the results of a minimum 21-year followup of a consecutive series of 103 patients who had 136 Marmor cemented unicompartmental knee replacements done between 1975 and 1982. Patients were evaluated clinically and radiographically. At minimum 21-year followup 14 patients (19 knees) were alive, 87 patients (115 knees) had died, and only two patients (two knees) were lost to followup. The average age at surgery was 70.9 years. The average followup Hospital for Special Surgery knee score was 58. The average Knee Society final followup clinical and functional scores averaged 72 and 53 points, respectively. Nineteen knees (14%) were revised during the 21-year followup period: nine for progression of disease, eight for loosening, and two for pain, at an average of 10.6 years (range, 1-22 years). Of the 19 knees in the 14 patients who were still alive at final followup, seven (37%) were revised: two for tibial loosening, four for disease progression, and one for pain. Unicompartmental knee replacements in this relatively older age group of patients performed well at minimum 21-year followup. Although we are encouraged by these results, only 22% were done in patients who were younger than 65 years at the time of surgery and the results in this group were significantly less durable. LEVEL OF EVIDENCE: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.