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Total knee arthroplasty for severe valgus deformity. Five to fourteen-year follow-up.

BACKGROUND: In 1985, the senior author (C.S.R.) developed a new soft-tissue release technique to balance valgus knees to avoid unacceptably high rates of late-onset instability and the need for primary constrained implants. This report describes the soft-tissue release technique and its long-term results when performed in primary total knee arthroplasty in patients with a severe valgus knee deformity. METHODS: Four hundred and ninety consecutive total knee arthroplasties were performed by one surgeon between January 1988 and December 1992. In this group, seventy-one patients (eighty-five knees) had a valgus deformity of > or =10 degrees . Thirty-two patients (thirty-six knees) died, and four patients (seven knees) were lost to follow-up, leaving thirty-five patients (forty-two knees) followed for a minimum of five years. These twenty-seven women and eight men had a mean age of sixty-seven years at the time of the index operation. The technique included an inside-out soft-tissue release of the posterolateral aspect of the capsule with pie-crusting of the iliotibial band and resection of the proximal part of the tibia and distal part of the femur to provide a balanced, rectangular space. Cemented, posterior stabilized implants were used in all knees. Clinical and radiographic evaluations were performed at one, five, and ten years postoperatively. RESULTS: The mean modified Knee Society clinical score improved from 30 points preoperatively to 93 points postoperatively, and the mean functional score improved from 34 to 81 points. The mean range of motion was 110 degrees both preoperatively and postoperatively. The mean coronal alignment was corrected from 15 degrees of valgus preoperatively to 5 degrees of valgus postoperatively. Three patients underwent revision surgery because of delayed infection, premature polyethylene wear, and patellar loosening in one patient each. There were no cases of delayed instability. CONCLUSIONS: The inside-out release technique to correct a fixed valgus deformity in patients undergoing primary total knee arthroplasty is reproducible and provides excellent long-term results. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Adult↗

Modular fixed-bearing total knee arthroplasty with retention of the posterior cruciate ligament. A study of patients followed for a minimum of fifteen years.

BACKGROUND: There have been a limited number of studies of total knee arthroplasties with durations of follow-up of fifteen years, but we are not aware of any involving modular fixed-bearing posterior cruciate-retaining prostheses. METHODS: A consecutive series of 139 total knee arthroplasties in 109 patients (average age, sixty-seven years), performed by one surgeon using a nonconforming posterior cruciate-retaining prosthesis, was followed for fifteen years or longer. Forty-five patients (fifty-nine knees) were examined at a minimum of fifteen years postoperatively, fifty-seven patients (seventy knees) had died, five patients (eight knees) were too ill to return for assessment, and two patients (two knees) were considered lost to follow-up. The patients were assessed clinically with use of the Knee Society clinical rating system, and the knees were assessed radiographically. Survivorship analysis was performed with use of worst-case-scenario analysis and with failure defined as a reoperation for any reason. RESULTS: There were five reoperations, four of which were performed because of wear of the polyethylene insert. In addition, one loose cemented femoral component was revised at fifteen years. The survival rate without revision or a need for any reoperation was 92.6% at fifteen years. The mean Knee Society score and functional score at fifteen years were 96 and 78 points, respectively. The prevalence of radiolucent lines was 13%, with 2% around the femur, 11% around the tibia, and none around the patella. None of these lines were clinically relevant. There was no evidence of progressive radiolucent lines, and there was one case of asymptomatic femoral osteolysis. CONCLUSIONS: In this single-surgeon series, modular fixed-bearing posterior cruciate-retaining total knee arthroplasties had good clinical and radiographic results with excellent survivorship for up to fifteen years. These results are comparable with those in long-term studies of posterior stabilized implants and of prostheses with mobile-bearing and nonmodular tibial inserts.

Adolescent↗

Alumina-on-alumina total hip arthroplasty. A five-year minimum follow-up study.

BACKGROUND: Ceramic-on-ceramic couplings are attractive alternative bearing surfaces that have been reported to eliminate or reduce problems related to polyethylene wear debris. Disappointing experiences with alumina ceramic bearings in the past have led to many improvements in the manufacture and design of ceramic implants. The purpose of the present study was to report the results of contemporary alumina-on-alumina total hip arthroplasties with regard to wear, osteolysis, and fracture of the ceramic after a minimum duration of follow-up of five years. METHODS: We evaluated the results of a consecutive series of 100 primary alumina-on-alumina total hip arthroplasties that had been performed with use of a metal-backed socket and a cementless stem in eighty-four patients. All of the patients were sixty-five years of age or younger (mean age, forty-one years), and a single surgeon performed all of the procedures. After a minimum duration of follow-up of sixty months, one patient (one hip) had died and four patients (six hips) had been lost to follow-up, leaving a total of seventy-nine patients (ninety-three hips) available for study. All of these patients were evaluated clinically and radiographically with special attention to wear, periprosthetic osteolysis, and ceramic failure. RESULTS: The mean Harris hip score was 97 points at the time of the latest follow-up evaluation. All prostheses demonstrated radiographic evidence of bone ingrowth. No implant was loose radiographically, and no implant was revised. Ceramic wear was not detectable in the thirty-seven hips in which the femoral head could be differentiated from the cup on radiographs. Periprosthetic osteolysis was not observed in any hip. A fracture of the alumina femoral head and a peripheral chip fracture of the alumina insert occurred in one hip following a motor-vehicle accident. CONCLUSIONS: The results of contemporary alumina-on-alumina total hip arthroplasty with a metal-backed socket and a cementless stem were encouraging after a minimum duration of follow-up of five years. We believe that these improved alumina-on-alumina bearing implants offer a promising option for younger, active patients.

Adolescent↗

Clinical performance of a Durasul highly cross-linked polyethylene acetabular liner for total hip arthroplasty at five years.

BACKGROUND: Highly cross-linked polyethylene is currently the most common articulation surface used for total hip arthroplasty. The hypothesis of the present study was that the Durasul highly cross-linked polyethylene acetabular liner would have less wear at five years than would a conventional polyethylene liner used in association with the same total hip replacement system. METHODS: Forty-three consecutive patients (fifty hips) underwent total hip replacement with an uncemented titanium porous-coated metal cup and a Durasul liner that was mated with a 28-mm cobalt-chromium femoral head. Thirty-one patients (thirty-seven hips) were followed for at least five years. Thirty-five other patients (thirty-seven hips) underwent total hip arthroplasty with the same system but with a conventional polyethylene liner, and these patients also were followed for five years. Clinical assessment was performed with use of the Harris hip score and a patient self-assessment examination. Radiographic analysis included measurements of acetabular component position, fixation, and osteolysis. Femoral head penetration of the Durasul liners was compared with that of the conventional liners. RESULTS: The clinical results as determined on the basis of Harris hip scores and patient self-assessment examinations did not differ between the Durasul group and the control group. The mean bedding-in penetration was 0.054 +/- 0.07 mm for the Durasul group and 0.059 +/- 0.154 mm for the control group. The subsequent penetration, with elimination of the bedding-in wear, resulted in a linear wear rate of 0.029 +/- 0.02 mm per year for the Durasul group, compared with 0.065 +/- 0.03 mm per year for the control group (p < 0.005). The annual penetration at one and five years was 0.074 mm and 0.011 mm, respectively, for the Durasul group, compared with 0.151 mm and 0.04 mm, respectively, for the control group. CONCLUSIONS: While the qualitative wear pattern of the highly cross-linked polyethylene liner was the same as that of the conventional polyethylene liner, the annual linear wear rate was 45% of that seen with the conventional polyethylene liner. Therefore, we believe that these early data support the continued use of this highly cross-linked polyethylene liner for total hip arthroplasty.

Adult↗

Early quadriceps strength loss after total knee arthroplasty. The contributions of muscle atrophy and failure of voluntary muscle activation.

BACKGROUND: While total knee arthroplasty reduces pain and provides a functional range of motion of the knee, quadriceps weakness and reduced functional capacity typically are still present one year after surgery. The purpose of the present investigation was to determine the role of failure of voluntary muscle activation and muscle atrophy in the early loss of quadriceps strength after surgery. METHODS: Twenty patients with unilateral knee osteoarthritis were tested an average of ten days before and twenty-seven days after primary total knee arthroplasty. Quadriceps strength and voluntary muscle activation were measured with use of a burst-superimposition technique in which a supramaximal burst of electrical stimulation is superimposed on a maximum voluntary isometric contraction. Maximal quadriceps cross-sectional area was assessed with use of magnetic resonance imaging. RESULTS: Postoperatively, quadriceps strength was decreased by 62%, voluntary activation was decreased by 17%, and maximal cross-sectional area was decreased by 10% in comparison with the preoperative values; these differences were significant (p < 0.01). Collectively, failure of voluntary muscle activation and atrophy explained 85% of the loss of quadriceps strength (p < 0.001). Multiple linear regression analysis revealed that failure of voluntary activation contributed nearly twice as much as atrophy did to the loss of quadriceps strength. The severity of knee pain with muscle contraction did not change significantly compared with the preoperative level (p = 0.31). Changes in knee pain during strength-testing did not account for a significant amount of the change in voluntary activation (p = 0.14). CONCLUSIONS: Patients who are managed with total knee arthroplasty have profound impairment of quadriceps strength one month after surgery. This impairment is predominantly due to failure of voluntary muscle activation, and it is also influenced, to a lesser degree, by muscle atrophy. Knee pain with muscle contraction played a surprisingly small role in the reduction of muscle activation.

Aged↗

Patellar resurfacing in total knee arthroplasty. A meta-analysis.

BACKGROUND: Patellar resurfacing during total knee arthroplasty remains controversial. We aimed to evaluate the effectiveness of this technique through an evaluation of the current literature. METHODS: We performed a meta-analysis of randomized controlled trials comparing total knee arthroplasties performed with and without patellar resurfacing. Outcomes of interest included the number of reoperations, the prevalence of postoperative anterior knee pain, and the improvement in various knee scores. RESULTS: Ten trials assessing 1223 knees were eligible. The absolute risk of reoperation was reduced by 4.6% (95% confidence interval, 1.9% to 7.3%) in the patellar resurfacing arm (between-study heterogeneity, p < 0.01; I(2) = 60%), implying that one would have to resurface twenty-two patellae (95% confidence interval, fourteen to fifty-two patellae) in order to prevent one reoperation. Patellar resurfacing reduced the absolute risk of postoperative anterior knee pain by 13.8% (95% confidence interval, 6.4% to 21.2%), implying that one would have to resurface seven patellae (95% confidence interval, five to sixteen patellae) in order to prevent one case of postoperative anterior knee pain. Only four trials provided adequate data for a quantitative synthesis of the changes in the various knee scores; on the basis of those four trials, there was no difference in the mean improvement in the knee scores (standardized mean difference, 0.03; 95% confidence interval, -0.50 to 0.56). CONCLUSIONS: The available evidence indicates that patellar resurfacing reduces the risks of reoperation and anterior knee pain after total knee arthroplasty. The observed effects are clinically important despite their modest magnitude. Additional, carefully designed randomized trials are required to strengthen this claim.

Aged↗

The effect of femoral notching during total knee arthroplasty on the prevalence of postoperative femoral fractures and on clinical outcome.

BACKGROUND: The treatment of a supracondylar femoral fracture following total knee arthroplasty is complicated by the presence of the prosthetic components. Anterior femoral notching during arthroplasty has been implicated as a contributing risk factor for femoral fracture. We retrospectively reviewed the effect of anterior femoral notching on the subsequent occurrence of a periprosthetic supracondylar fracture of the distal aspect of the femur and the outcomes of primary total knee arthroplasty in such patients. METHODS: The prevalence and depth of femoral notching were determined on a review of the lateral radiographs by observers blinded to the clinical results of 1089 consecutive total knee replacements performed in 1997 and 1998. Linear and logistic regression modeling was used to analyze the relationship between femoral notching and the prevalence of supracondylar femoral fracture, postoperative range of motion, the Knee Society score, and the Knee Society functional and pain scores. RESULTS: Femoral notching was performed in 325 (29.8%) of the 1089 knees in our series. During an average follow-up period of 5.1 years, only two supracondylar femoral fractures occurred, both in femora treated without notching. Femoral notching was not associated with an increased rate of fracture (p = 1.000) or with significant differences in the measures of outcome (range of motion [p = 0.117], knee score [p = 0.967], functional score [p = 0.861], need for a lateral release [p = 0.234], or postoperative pain [p = 0.948]). CONCLUSIONS: This study demonstrated no difference in knees managed with or without notching of the anterior distal aspect of the femur with respect to the occurrence of a supracondylar fracture, range of motion, Knee Society score, Knee Society function, or pain.

Adult↗

Debridement arthroplasty for primary osteoarthritis of the elbow. Surgical technique.

BACKGROUND: Formal and more aggressive debridement procedures have been described for the treatment of advanced primary osteoarthritis of the elbow. However, the literature contains little information on the results of long-term follow-up. The purpose of this study was to evaluate outcomes at an average of ten years after debridement arthroplasties performed through a posteromedial approach. METHODS: Thirty-three elbows with primary osteoarthritis in thirty-two patients treated with debridement arthroplasty were available for clinical follow-up evaluation. Through a posteromedial approach, the flexor-pronator muscle origin was reflected from the medial epicondyle and the joint was opened, preserving the anterior oblique bundle of the medial collateral ligament. The ulnar nerve was decompressed in all patients. Osteophytes were removed from the anterior, medial, and posterior sides of the elbow joint. In nine elbows, osteophytes from the lateral compartment were removed through an additional lateral approach. The mean age at the time of the operation was fifty years. The mean duration of follow-up was 121 months, and nineteen elbows were followed for more than ten years. RESULTS: The mean preoperative limitation of extension of 31 degrees was reduced to 24 degrees , and the mean preoperative flexion of 101 degrees improved to 118 degrees (p < 0.001). The mean arc of movement improved by 24 degrees . The mean Japanese Orthopaedic Association elbow score was 83 points at the latest follow-up evaluation compared with 60 points preoperatively (p < 0.001). Of twenty-five patients who had performed heavy manual work, nineteen (76%) returned to their previous job or an equivalent job. At the latest examination of the nineteen elbows followed for more than ten years, the limitation of extension was found to have increased by 7 degrees compared with the limitation noted at one year (p < 0.009); the mean arc of flexion had remained the same. Three elbows required a reoperation. Overall, 85% of the elbows were satisfactory to the patients. CONCLUSIONS: Debridement arthroplasty through a posteromedial approach can provide stable and reliable long-term results with regard to relief of pain, gains in range of motion, and the patient's ability to return to his or her previous occupation. In our series, a modest loss of extension was observed at ten years, whereas the arc of flexion remained consistent.

Arthroplasty↗

Evaluation of a single-dose, extended-release epidural morphine formulation for pain after knee arthroplasty.

BACKGROUND: DepoDur is a single-dose, extended-release epidural morphine formulation designed to provide forty-eight hours of pain relief. The drug offers potential advantages over continuous epidural infusions, particularly in patients being treated with anticoagulation therapy. The purpose of this study was to evaluate the efficacy and safety of single-dose epidural DepoDur for pain control following knee arthroplasty. METHODS: In this multicenter, randomized, double-blind, parallel-group study, patients were randomized to receive a single-dose of DepoDur (20 or 30 mg) or a sham epidural injection thirty minutes before administration of general or regional anesthesia for knee arthroplasty. At their first request for postoperative analgesia, patients who had received DepoDur were given an intravenous bolus of hydromorphone followed by placebo patient-controlled analgesia. Patients who had received the sham epidural were given an intravenous bolus of morphine followed by patient-controlled analgesia with morphine. Patient ratings of pain intensity at rest and with activity, their rating of overall pain control, and postoperative opioid use were recorded. The ability to tolerate physical therapy, the range of motion of the knee, and the need for physical support were assessed as well. Adverse events and vital signs were recorded. RESULTS: Of 168 patients randomized to receive the 20-mg injection of DepoDur, the 30-mg injection of DepoDur, or the sham epidural injection, fifty-one, fifty-eight, and fifty-five patients, respectively, were included in the efficacy analysis. Compared with the patients treated with intravenous patient-controlled analgesia with morphine, the patients treated with DepoDur had significantly reduced mean pain-intensity-recall scores during the four to eight, four to twelve, four to twenty-four, and four to thirty-hour postdose intervals (p < 0.05 for all comparisons). The patients treated with DepoDur used approximately a threefold lower amount of postoperative opioids in total, with a significant percentage requiring no supplemental opioids. Adverse events common to all groups were nausea (78%), pyrexia (46%), vomiting (43%), pruritus (43%), and hypotension (36%). Respiratory depression was the most common serious adverse event, with serious respiratory depression observed in four DepoDur-treated patients, who were more than sixty-five years of age. CONCLUSIONS: With appropriate patient selection and monitoring, perioperative single-dose epidural DepoDur was a safe and effective analgesic alternative to postoperative intravenous patient-controlled analgesia following knee arthroplasty, with younger patients benefiting from the 20-mg dose. Additional studies of 10 to 15-mg doses for older patients are warranted.

Adult↗

Osteolysis after total knee arthroplasty: influence of tibial baseplate surface finish and sterilization of polyethylene insert. Findings at five to ten years postoperatively.

BACKGROUND: Debris displaced from the articular and backside surfaces of the polyethylene inserts of modular tibial components is considered a chief cause of osteolysis at the sites of total knee arthroplasties. One design of total knee replacement featured changes, over time, in the proximal surface roughness of the tibial baseplate and the method of sterilization of the polyethylene insert. We hypothesized that polishing the baseplate surface and sterilizing the insert with means other than gamma radiation in air had reduced the prevalence of osteolysis. METHODS: Three hundred and sixty-five posterior cruciate ligament-retaining Anatomic Modular Knee primary total knee arthroplasties were performed in 300 patients from 1987 to 1998. Anteroposterior and lateral radiographs of the knees were made within a five to ten-year postoperative interval. Two arthroplasty specialists independently examined the radiographs for evidence of osteolysis (defined as any nonlinear region of cancellous bone loss with delineable margins). RESULTS: Osteolysis was identified in 34% (eighty-two) of 242 knees treated with an insert that had been gamma-irradiated in air and affixed to a rough baseplate surface, and it was identified in 9% (nine) of ninety-eight knees treated with an insert that had been gamma-irradiated in an inert gas, or had not been irradiated, and joined to a polished surface. Osteolysis was associated with six factors, including one related to the patient (male gender), one related to the tibial baseplate (the proximal surface finish), three related to the polyethylene insert (the material from which it was machined, the sterilization method, and the shelf age), and one related to the technique (hyperextension of the femoral component relative to the tibial component). CONCLUSIONS: In this design of a total knee prosthesis, polishing the tibial baseplate counterface and implementing a more contemporary sterilization practice (as opposed to gamma radiation in air) noticeably diminished but did not eliminate osteolysis.

Aged↗

Total knee arthroplasty for severe valgus deformity.

BACKGROUND: In 1985, the senior author (C.S.R.) developed a new soft-tissue release technique to balance valgus knees to avoid unacceptably high rates of late-onset instability and the need for primary constrained implants. This report describes the soft-tissue release technique and its long-term results when performed in primary total knee arthroplasty in patients with a severe valgus knee deformity. METHODS: Four hundred and ninety consecutive total knee arthroplasties were performed by one surgeon between January 1988 and December 1992. In this group, seventy-one patients (eighty-five knees) had a valgus deformity of 10 degrees . Thirty-two patients (thirty-six knees) died, and four patients (seven knees) were lost to follow-up, leaving thirty-five patients (forty-two knees) followed for a minimum of five years. These twenty-seven women and eight men had a mean age of sixty-seven years at the time of the index operation. The technique included an inside-out soft-tissue release of the posterolateral aspect of the capsule with pie-crusting of the iliotibial band and resection of the proximal part of the tibia and distal part of the femur to provide a balanced, rectangular space. Cemented, posterior stabilized implants were used in all knees. Clinical and radiographic evaluations were performed at one, five, and ten years postoperatively. RESULTS: The mean modified Knee Society clinical score improved from 30 points preoperatively to 93 points postoperatively, and the mean functional score improved from 34 to 81 points. The mean range of motion was 110 degrees both preoperatively and postoperatively. The mean coronal alignment was corrected from 15 degrees of valgus preoperatively to 5 degrees of valgus postoperatively. Three patients underwent revision surgery because of delayed infection, premature polyethylene wear, and patellar loosening in one patient each. There were no cases of delayed instability. CONCLUSIONS: The inside-out release technique to correct a fixed valgus deformity in patients undergoing primary total knee arthroplasty is reproducible and provides excellent long-term results.

Aged↗

Custom patellofemoral arthroplasty of the knee.

BACKGROUND: The treatment of isolated patellofemoral arthritis is controversial. Several surgical procedures have been used to treat the severely degenerated patellofemoral joint, with varying degrees of success. The purpose of this study was to determine the clinical results of a custom patellofemoral arthroplasty for the treatment of isolated patellofemoral degenerative arthritis of the knee. METHODS: From 1995 through 2002, twenty-five patellofemoral replacements, three of which were bilateral, were performed in twenty-two patients for the treatment of isolated patellofemoral arthritis of the knee. According to the Ahl-back radiographic evaluation scale, the mean preoperative score for the severity of the arthritis was 4.65 points in the patellofemoral compartment and 0.5 point in both the medial and the lateral compartment. The patients included sixteen women (two of whom had a bilateral replacement) and six men (one of whom had a bilateral replacement) with a mean age of forty-five years at the time of the index arthroplasty. Seventeen patients (nineteen knees) had had a prior procedure on the knee. The mean preoperative Knee Society functional score was 49 points, and the mean preoperative Knee Society objective score was 52 points. RESULTS: At a mean of seventy-three months (range, thirty-two to 119 months) postoperatively, all twenty-five implants were in place and functioning well. There were eighteen excellent and seven good results. The mean Knee Society functional score was 89 points, and the mean Knee Society objective score was 91 points. No patient had required additional surgery or had component loosening. CONCLUSIONS: On the basis of our relatively short-term follow-up study, custom patellofemoral arthroplasty appears to be a safe and effective treatment for isolated patellofemoral arthritis of the knee. We believe that the results presented in this paper justify the additional cost associated with the custom device. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Adult↗

Extensor mechanism allograft reconstruction after total knee arthroplasty.

BACKGROUND: Disruption of the extensor mechanism is an uncommon but catastrophic complication of total knee arthroplasty. We evaluated two techniques of reconstructing a disrupted extensor mechanism with the use of an extensor mechanism allograft in revision total knee arthroplasty. METHODS: Twenty consecutive reconstructions with the use of an extensor mechanism allograft consisting of the tibial tubercle, patellar tendon, patella, and quadriceps tendon were performed. The first seven reconstructions (Group I) were done with the allograft minimally tensioned. The thirteen subsequent procedures (Group II) were performed with the allograft tightly tensioned in full extension. All surviving allografts were evaluated clinically and radiographically after a minimum duration of follow-up of twenty-four months. RESULTS: All of the reconstructions in Group I were clinical failures, with an average postoperative extensor lag of 59 degrees (range, 40 degrees to 80 degrees ) and an average postoperative Hospital for Special Surgery knee score of 52 points. All thirteen reconstructions in Group II were clinical successes, with an average postoperative extensor lag of 4.3 degrees (range, 0 degrees to 15 degrees ) (p < 0.0001) and an average Hospital for Special Surgery score of 88 points. Postoperative flexion did not differ significantly between Group I (average, 108 degrees ) and Group II (average, 104 degrees ) (p = 0.549). CONCLUSIONS: The results of reconstruction with an extensor mechanism allograft after total knee arthroplasty depend on the initial tensioning of the allograft. Loosely tensioned allografts result in a persistent extension lag and clinical failure. Allografts that are tightly tensioned in full extension can restore active knee extension and result in clinical success. On the basis of the number of knees that we studied, there was no significant loss of flexion. Use of an extensor mechanism graft for the treatment of a failure of the extensor mechanism will be successful only if the graft is initially tensioned tightly in full extension.

Arthroplasty, Replacement, Knee↗

Arthrodesis of the knee with a long intramedullary nail following the failure of a total knee arthroplasty as the result of infection.

BACKGROUND: Knee arthrodesis can be an effective treatment option for relieving pain and restoring some function after the failure of a total knee arthroplasty as the result of infection. The purpose of the present study was to review the outcome of a staged approach for arthrodesis of the knee with a long intramedullary nail after the failure of a total knee arthroplasty as the result of infection. METHODS: We reviewed the results for twelve patients who underwent knee arthrodesis after the removal of a prosthesis because of infection. The study group included seven women and five men who had an average age of sixty-eight years at the time of the arthrodesis. All patients were managed with a staged protocol. Implant removal, débridement, and insertion of antibiotic cement spacers was followed by the administration of systemic antibiotics. Provided that clinical and laboratory data suggested eradication of the infection, arthrodesis of the affected knee with use of a long intramedullary nail was carried out. Clinical and laboratory evaluation and radiographic analysis were performed after an average duration of follow-up of 4.1 years. RESULTS: Solid union was achieved in ten of the twelve knees. The average time to union was 5.5 months. One patient had an above-the-knee amputation because of recurrence of infection. In another patient, nail breakage occurred three years following implantation. The average limb-length discrepancy was 5.5 cm. The mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score improved from 41 to 64 points. None of the seven patients who underwent arthrodesis with a technique involving convex-to-concave reamers had a complication, and the average time to union for these seven patients was shorter than that for the remaining five patients (4.3 compared with 7.4 months). CONCLUSIONS: We believe that obtaining large surfaces of bleeding contact bone during arthrodesis following staged treatment of an infection at the site of a failed total knee arthroplasty contributes to stability and enhances bone-healing. Staged arthrodesis with use of a long intramedullary nail and convex-to-concave preparation of bone ends provided a painless functional gait with low complication and reoperation rates in this challenging group of patients.

Aged↗

Intraoperative fractures of the acetabulum during primary total hip arthroplasty.

BACKGROUND: The intraoperative occurrence of an acetabular fracture is a rare complication of primary total hip arthroplasty. Previous reports have lacked a sufficiently large number of subjects to allow for an analysis of the causes and appropriate treatment of this problem. METHODS: Between 1990 and 2000, 7121 primary total hip arthroplasties were performed at our institution. We retrospectively reviewed the records in our Total Joint Registry and found that twenty-one patients (twenty-one hips) had sustained an intraoperative acetabular fracture. Nineteen of these patients (nineteen hips) had been followed until revision or for a minimum of two years (mean duration of follow-up, forty-four months). We evaluated the anatomic location, cause, treatment, and outcome of the fractures. Acetabular component designs were categorized as modular, nonmodular (monoblock), true hemispherical, or elliptical, and then each design was analyzed for fracture risk. RESULTS: No fractures occurred in association with cemented acetabular components. The fracture rate associated with uncemented components was 0.4%. In seventeen hips, the acetabular component was judged to be stable despite the detection of a fracture and the cup was retained. In four hips, the original cup was not stable and therefore was replaced with a design that allowed for supplemental screw fixation. All fractures united, and all cups demonstrated osseous ingrowth at the time of the most recent follow-up. Elliptical monoblock cups were associated with a significantly higher fracture rate than were elliptical modular cups (p < 0.0001) and hemispherical modular cups (p < 0.0001). There was no significant difference between elliptical modular and hemispherical modular components with regard to the fracture rate. CONCLUSIONS: Acetabular fracture during primary total hip arthroplasty is a rare complication of acetabular fixation without cement. In the present series, retention of a stable cup was associated with uneventful osseous ingrowth and excellent early-term outcomes. We found a high rate of fracture in association with the use of monoblock elliptical components. LEVEL OF EVIDENCE: Therapeutic Level III.

Acetabulum↗

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.

Adult↗

The effect of ankle rotation on cutting of the tibia in total knee arthroplasty.

BACKGROUND: Extramedullary alignment guides are commonly used to prepare the tibia during total knee arthroplasty. One disadvantage is that the guide is easily affected by the position of the ankle joint. The tibia may have a rotational mismatch between its proximal and distal ends. We hypothesized that a rotational mismatch might cause incorrect positioning of an extramedullary alignment guide and evaluated such a mismatch on the predicted postoperative coronal alignment of the tibia. METHODS: Fifty-three osteoarthritic knees with varus deformity in fifty-one patients were evaluated with use of computerized tomography scans before total knee arthroplasty. We defined one anteroposterior axis of the ankle joint and five different anteroposterior axes of the proximal aspect of the tibia using three-dimensional bone models from the computerized tomography data. We measured the rotational angle between the anteroposterior axis of the ankle joint and the proximal part of the tibia. The distal end of the extramedullary guide was placed in front of the center of the ankle joint (on the line of the extended anteroposterior axis of the ankle joint), and the proximal end was placed on the line of the extended anteroposterior axis of the proximal part of the tibia. We established spatial coordinates to evaluate the effect of the rotational angle on the predicted postoperative coronal alignment of the tibia and calculated the presumed tibial coronal alignment. RESULTS: The rotational angle was positive (3.6 degrees to 19.7 degrees) for all of the anteroposterior axes of the proximal aspect of the tibia, indicating that the ankle joint was externally rotated relative to the proximal part of the tibia. The predicted tibial coronal alignment was varus (0.5 degrees to 5.1 degrees) for all of the anteroposterior axes of the proximal part of the tibia. CONCLUSIONS: When an extramedullary alignment guide is used to prepare the tibia in total knee arthroplasty, varus alignment of the tibial component can occur because of a rotational mismatch between the proximal part of the tibia and the ankle joint.

Aged↗

Serum and breast milk levels of methylmethacrylate following surgeon exposure during arthroplasty.

BACKGROUND: Although pregnant personnel are commonly encouraged to leave the operating room during the mixing and application of polymethylmethacrylate, we are not aware of any information regarding the safety of exposure to methylmethacrylate fumes for breastfeeding women. The present study was performed to investigate the concentrations of methylmethacrylate in serum and breast milk following exposure during total joint arthroplasty. METHODS: A survey designed to determine present-day attitudes to polymethylmethacrylate exposure during pregnancy and lactation was sent to members of the Ruth Jackson Orthopaedic Society and the National Association of Orthopaedic Nurses. To define the presence or absence of a scientific basis for this behavior, serum and breast milk samples were collected from two lactating surgeons at selected intervals after exposure to methylmethacrylate during eight total joint arthroplasty procedures. Two healthy breastfeeding women without exposure to methylmethacrylate served as controls. All twenty-five samples were analyzed for methylmethacrylate with use of a previously published headspace gas chromatography protocol. RESULTS: The gas chromatography protocol detected methylmethacrylate at levels as low as 0.5 part per million. No serum or breast milk sample demonstrated evidence of methylmethacrylate at that level, nor did any surgeon sample test at a higher level than the control specimens. Serum and milk samples spiked with methylmethacrylate yielded the analyte peak as expected, evidencing no interference from either matrix. CONCLUSIONS: Methylmethacrylate was not detectable at the 0.5-part-per-million level in serum or breast milk following inhalational exposure during total joint arthroplasty. Although a controlled longitudinal relative risk analysis was not performed and the sample size was relatively small, pregnant or breastfeeding women may use this information to make an informed decision regarding such exposure. LEVEL OF EVIDENCE: Therapeutic Level II.

Adult↗