Mike B. Anderson

Fixation, Polyethylene Wear, and Pelvic Osteolysis in Primary Total Hip Replacement

A multicenter retrospective review was performed analyzing 1081 primary total hip replacements in 944 patients using the Harris Galante-I cementless acetabular component with screw fixation. All patients were followed up for a minimum of 5 years with a mean followup of 81 months. Linear polyethylene wear averaged 0.11 mm/year (range, 0-0.86 mm/year). Pelvic osteolysis was seen in 25 patients (2.3%). Migration of the acetabular component was seen in four hips. A subgroup of patients was reanalyzed at a minimum followup of 10 years. The mean linear polyethylene wear rate remained 0.11 mm/year. In this group, only one socket had migrated. There was an association between wear rate and age. On average, younger patients had higher wear rates. The risk for having pelvic osteolysis develop and the need for revision surgery also was age-related. Twenty-two percent of hip replacements (15 hips) in patients younger than 50 years of age at the time of their index operation had pelvic osteolysis develop. In contrast, for patients older than 50 years of age at the time of surgery only 7.8% (eight hips) had osteolysis of the pelvis develop. For patients older than 70 years of age at the time of primary total hip replacement, none had pelvic osteolysis develop.

The value of preliminary traction in the treatment of congenital dislocation of the hip

In forty-one children who had forty-seven congenitally dislocated hips, the results of attempted closed reduction with general anesthesia, but without preliminary traction, were studied. Twenty (43 per cent) of the hips could not be reduced closed, and an open reduction was needed. After the reduction, all of the involved hips were immobilized in the so-called human position (marked flexion and slight abduction). At a minimum follow-up of two years, osteonecrosis of the femoral head had developed in only two hips (4 per cent). Patients who were more than one year old when the hip was reduced had a higher incidence of osteonecrosis of the femoral head and were more likely to need reconstructive procedures later. Patients who were more than eighteen months old at the time of the attempted closed reduction were more likely to need an open reduction of the hip. Treatment of congenital dislocation of the hip in young children remains an extremely complex problem. It has not been clearly established that the use of preliminary traction decreases the incidence of osteonecrosis of the femoral head or improves the outcome of treatment. In our experience, uncomplicated (non-teratological, postnatal) congenital dislocation of the hip has been safely treated with either open or closed reduction without preliminary traction in patients who were younger than two years old, provided that the reduction could be obtained without excessive force.

Postoperative falls after total knee arthroplasty in patients with a femoral nerve catheter: Can we reduce the incidence?

A femoral nerve catheter (FNC) is often used to minimize pain following total knee arthroplasty (TKA), but complications including inpatient falls, may increase as a result, despite fall prevention protocols. We evaluated the rate of falls in 707 primary TKAs performed with an FNC at a major academic center from May 2009 to September 2012. Despite a formalized fall prevention protocol, we found 19 falls (2.7%). Three patients required further operative intervention. At a rate of 2.7%, postoperative fall is one of the most common complications of TKA at our institution. While pain control may be good with the use of FNCs following primary TKA, improvements in fall prevention strategies or the use of alternative postoperative pain control modalities may need to be considered.

Comparison of Total Knee Arthroplasty With Highly Congruent Anterior-stabilized Bearings versus a Cruciate-retaining Design

BackgroundThe use of a highly conforming, anterior-stabilized bearing has been associated with clinical success in a limited number of studies.Questions/purposesWe compared Knee Society scores, radiographic results, complication rates, and revision rates with the use of anterior-stabilized bearings compared with cruciate-retaining (CR) bearings.MethodsA series of 382 patients with 468 primary total knee arthroplasties (TKAs) between 2003 and 2008 with minimum 2-year followup were reviewed. Anterior-stabilized bearings comprised 49% (n = 228) of the sample and CR bearings consisted of 51% (n = 240). The decision to use an anterior-stabilized bearing was based on integrity of the posterior cruciate ligament (PCL) intraoperatively or after sacrifice of the PCL to achieve soft tissue balance. The tibial and femoral component designs were the same regardless of bearing choice. Outcomes were measured with Knee Society scores, complications, revision TKA, and survival. Radiographs were analyzed for component alignment and evidence of loosening.ResultsThere was no difference in Knee Society knee scores, radiographic alignment, component loosening, manipulation rate, major complications, or time to revision for patients between the two groups. However, the CR group had significantly more revisions than the anterior-stabilized group (21 CR [1.5%] versus seven anterior-stabilized [4.6%], p = 0.03) at a minimum followup of 5 months (mean, 42 months; range, 5–181 months).ConclusionsThe use of a highly congruent anterior-stabilized bearing for PCL substitution has comparable clinical and radiographic results to traditional CR TKA. These results suggest that this approach is an effective method to achieve stability without the PCL in primary TKA.Level of EvidenceLevel III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The Prevalence of Radiographic Findings of Structural Hip Deformities in Female Collegiate Athletes

Background: Structural deformities of the hip, including femoroacetabular impingement (FAI) and acetabular dysplasia, often limit athletic activity. Previous studies have reported an increased prevalence of radiographic cam FAI in male athletes, but data on the prevalence of structural hip deformities in female athletes are lacking. Purpose: (1) To quantify the prevalence of radiographic FAI deformities and acetabular dysplasia in female collegiate athletes from 3 sports: volleyball, soccer, and track and field. (2) To identify possible relationships between radiographic measures of hip morphologic characteristics and physical examination findings. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Anteroposterior (AP) pelvis and frog-leg lateral radiographs were obtained from 63 female athletes participating in Division I collegiate volleyball, soccer, and track and field. Lateral center edge angle (LCEA) and acetabular index were measured on AP films. Alpha angle and head-neck offset were measured on frog-leg lateral films. Pain during the supine impingement examination and hip rotation at 90° of flexion were recorded. Random-effects linear regression was used for group comparisons and correlation analyses to account for the lack of independence of observations made on left and right hips. Results: Radiographic cam deformity (alpha angle >50° and/or head-neck offset <8 mm) was found in 48% (61/126) of hips. Radiographic pincer deformity (LCEA >40°) was noted in only 1% (1/126) of hips. No hips had radiographic mixed FAI (at least 1 of the 2 cam criteria and LCEA >40°). Twenty-one percent (26/126) of hips had an LCEA <20°, indicative of acetabular dysplasia, and an additional 46% (58/126) of hips had borderline dysplasia (LCEA ≥20° and ≤25°). Track and field athletes had significantly increased alpha angles (48.2° ± 7.1°) compared with the soccer players (40.0° ± 6.8°; P < .001) and volleyball players (39.1° ± 5.9°; P < .001). There was no significant difference in the LCEA (all P > .914) or the prevalence of dysplasia (LCEA <20°) between teams (all P > .551). There were no significant correlations between the radiographic measures and internal rotation (all P > .077). There were no significant differences (all P > .089) in radiographic measures between hips that were painful (n = 26) during the impingement examination and those that were not. Conclusion: These female athletes had a lower prevalence of radiographic FAI deformities compared with previously reported values for male athletes and a higher prevalence of acetabular dysplasia than reported for women in previous studies.

Lessons Learned from Selective Soft-Tissue Release for Gap Balancing in Primary Total Knee Arthroplasty: An Analysis of 1216 Consecutive Total Knee Arthroplasties AAOS Exhibit Selection

BACKGROUND Soft-tissue releases are commonly necessary to achieve symmetrical flexion and extension gaps in primary total knee arthroplasty performed with a measured resection technique. We reviewed the frequency of required releases according to preoperative alignment and the clinical and radiographic results; associations with failure, reoperations, and complications are presented. METHODS We reviewed 1216 knees that underwent primary total knee arthroplasty from 2004 to 2009; 774 (64%) were in female patients and 442 (36%), in male patients. In the coronal plane, 855 knees had preoperative varus deformity, 123 were neutral, and 238 had valgus deformity. The mean age at the time of the index procedure was 62.7 years (range, twenty-three to ninety-four years), and the mean body mass index was 32.7 kg/m² (range, 17.4 to 87.9 kg/m²). Clinical outcomes included the Knee Society Score (KSS), implant failure, reoperation, and complications. Radiographs were analyzed for component alignment. RESULTS The only difference in the total KSS was found at the time of final follow-up between valgus knees with zero releases (total KSS = 178) and those with one or two releases (KSS = 160, p = 0.026). Overall, 407 knees (33.5%) required zero releases, 686 (56.4%) required one or two releases, and 123 (10.1%) required three or more releases. Among varus knees, 37% required zero releases, 55% required one or two releases, and 7.5% required three or more releases. Among neutral knees, 39% required zero releases, 55% required one or two releases, and 5.7% required three or more releases. Only 17% of valgus knees required zero releases whereas 61% required one or two releases and 21.8% required three or more releases. Valgus knees required more releases than neutral or varus knees did (p < 0.001). CONCLUSIONS Selective soft-tissue release for gap balancing in primary total knee arthroplasty is an effective technique that produced excellent clinical and radiographic results regardless of preoperative alignment. Consistent anatomic coronal-plane alignment and soft-tissue balance could be achieved without bone cut modification by using measured bone resection and selective soft-tissue release.

Psychometric Evaluation of the Lower Extremity Computerized Adaptive Test, the Modified Harris Hip Score, and the Hip Outcome Score

Background: The applicability and validity of many patient-reported outcome measures in the high-functioning population are not well understood. Purpose: To compare the psychometric properties of the modified Harris Hip Score (mHHS), the Hip Outcome Score activities of daily living subscale (HOS-ADL) and sports (HOS-sports), and the Lower Extremity Computerized Adaptive Test (LE CAT). The hypotheses was that all instruments would perform well but that the LE CAT would show superiority psychometrically because a combination of CAT and a large item bank allows for a high degree of measurement precision. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Data were collected from 472 advanced-age, active participants from the Huntsman World Senior Games in 2012. Validity evidences were examined through item fit, dimensionality, monotonicity, local independence, differential item functioning, person raw score to measure correlation, and instrument coverage (ie, ceiling and floor effects), and reliability evidences were examined through Cronbach alpha and person separation index. Results: All instruments demonstrated good item fit, unidimensionality, monotonicity, local independence, and person raw score to measure correlations. The HOS-ADL had high ceiling effects of 36.02%, and the mHHS had ceiling effects of 27.54%. The LE CAT had ceiling effects of 8.47%, and the HOS-sports had no ceiling effects. None of the instruments had any floor effects. The mHHS had a very low Cronbach alpha of 0.41 and an extremely low person separation index of 0.08. Reliabilities for the LE CAT were excellent and for the HOS-ADL and HOS-sports were good. Conclusion: The LE CAT showed better psychometric properties overall than the HOS-ADL, HOS-sports, and mHHS for the senior population. The mHHS demonstrated pronounced ceiling effects and poor reliabilities that should be of concern. The high ceiling effects for the HOS-ADL were also of concern. The LE CAT was superior in all psychometric aspects examined in this study. Future research should investigate the LE CAT for wider use in different populations.

Two-Stage Revision TKA Is Associated with High Complication and Failure Rates

Despite two-stage revision remaining the gold standard in treating periprosthetic infection of total knee arthroplasty (TKA), there remains uncertainty regarding the actual success rate and the risk factors for failure. We retrospectively reviewed 58 knees with mean follow-up of 38 months who underwent two-stage revision TKAs from 1998 to 2012 by a single surgeon. Failure was defined as persistent infection or reoperation after two-stage revision TKA surgery. Failure occurred in 36%. The overall mortality was 22%. The mean time to reinfection was 26 months. Polymicrobial infection was associated with a higher risk of failure (RR 3.31, P < 0.001). Knees requiring soft tissue coverage were also at a greater risk of failure (RR 2.67, P = 0.001), as were knees that underwent four or more additional surgeries after the primary TKA and prior to stage-one explantation (RR 2.25, P = 0.020). Thus, opportunities exist for improvement in management of infected TKA.

Higher Frequency of Reoperation With a New Bicruciate-retaining Total Knee Arthroplasty

BackgroundWith as many as 25% of patients reporting residual knee symptoms after primary total knee arthroplasty (TKA), alternative implant designs and surgical techniques have been proposed to further reduce these symptoms. There is growing evidence that retention of the anterior cruciate ligament (ACL) results in more natural knee kinematics; thus, implants with more normal joint mechanics could provide improved physical function postoperatively and reduce the amount of residual symptoms. Advancements in the bicruciate-retaining (BCR) TKA implant design have been made, and based on these, we wished to compare the BCR with a more traditional cruciate-retaining (CR) implant.Questions/purposes(1) Was there a difference in the risk of reoperation after primary TKA between BCR and CR implant designs? (2) Was there a difference in the radiographic findings of radiolucent lines (RLLs) between the implant designs? (3) Was there a difference in patient-reported and clinical outcomes between the two implant designs?MethodsBetween January 2013 and May 2014, two surgeons performed 475 primary TKAs. During this time, 78 (16%) of these were performed with BCR implants and 294 (62%) with CR implants; the remainder were performed with anterior-stabilized or more constrained designs as a result of increased deformity and/or ligamentous deficiencies. During this period, the general indications for BCR TKA were arthritic knees with only slight to moderate deformity and sufficient ligamentous integrity of both the ACL and posterior cruciate ligament. The indications for CR TKA were similar other than these patients presented with a deficient ACL. A total of 66 (85%) of the BCR and 237 (81%) of the CR TKAs were available for followup at a minimum of 12 months or when reoperation occurred before 12 months (mean, 18 months; range, 2–32 months). With the numbers available, there were no differences between the groups in terms of age and sex, but the patients undergoing CR TKA had a greater mean body mass index (33 ± 7 versus 31 ± 5 kg/m2, p = 0.032). The frequency of early reoperation was compared between the groups as were radiographic evidence of RLL, patient-reported outcomes, and knee range of motion (ROM).ResultsKnees in the BCR group had a higher frequency of all-cause revision (5% [three of 66] versus 1.3% [three of 237]; hazard ratio (HR), 7.44; 95% confidence interval [CI], 1.24–44.80; p = 0.028). Knees in the BCR group had a higher frequency of irrigation and débridement with component retention (HR, 0.07; 95% CI, 0.02–0.28; p < 0.001). No differences were found between groups for subsequent manipulation (HR, 0.34; 95% CI, 0.08–1.42; p = 0.137). The proportion of RLLs was greater in the BCR group (HR, 2.93; 95% CI, 1.62–5.32; p < 0.001) compared with the CR group. There were no differences between the groups in terms of the Physical Function Computerized Adaptive Test scores, Global10 scores or knee ROM outcomes.ConclusionsPreliminary short-term findings suggest the BCR implant has inferior survivorship and concerning radiographic findings when compared with a conventional CR implant with respect to complications after primary TKA. These findings raise concerns about the new BCR design; however, further randomized trials are necessary to determine superiority between alternative implant designs.Level of EvidenceLevel III, therapeutic study.

Continuous femoral nerve block using 0.125% bupivacaine does not prevent early ambulation after total knee arthroplasty.

BackgroundContinuous femoral nerve block has been shown to decrease opioid use, improve postoperative pain scores, and decrease length of stay. However, several studies have raised the concern that continuous femoral nerve block may delay patient ambulation and increase the risk of falls during the postoperative period.Questions/purposesThis study sought to determine whether continuous femoral nerve block with a single-shot sciatic block prevented early ambulation after total knee arthroplasty (TKA) and whether the technique was associated with adverse effects.MethodsBetween January 2011 and January 2013, 77 consecutive patients undergoing primary TKAs at an orthopaedic specialty hospital received a continuous femoral nerve block for perioperative analgesia. The femoral block was placed preoperatively with an initial bolus and 76 (99%) patients received a single-shot sciatic nerve block performed at the same time. Fifty-eight percent (n = 45) received an initial bolus of 0.125% bupivacaine and 42% (n = 32) received 0.25% bupivacaine. All 77 patients received 0.125% bupivacaine infusion postoperatively with the continuous femoral nerve block. All patients were provided a knee immobilizer that was worn while they were out of bed and was used until 24 hours after removal of the block. All patients also used a front-wheeled walker to assist with ambulation. All 77 patients had complete records for assessing the end points of interest in this retrospective case series, including distance ambulated each day and whether in-hospital complications could be attributed to the patients’ nerve blocks.ResultsThirty-five patients (45%) ambulated for a mean distance of 19 ± 22 feet on the day of surgery. On postoperative Days 1 and 2, all 77 patients successfully ambulated a mean of 160 ± 112 and 205 ± 123 feet, respectively. Forty-eight patients (62%) had documentation of ascending/descending stairs during their hospital stay. No patient fell during the postoperative period, required return to the operating room, or readmission within 90 days of surgery. One patient experienced a transient foot drop related to the sciatic nerve block, which resolved by postoperative Day 1.ConclusionsContinuous femoral nerve block with dilute bupivacaine (0.125%) can be successfully used after TKA without preventing early ambulation. By taking active steps to prevent in-hospital falls, including the use of a knee immobilizer for ambulation while the block is in effect, patients can benefit from the analgesia provided by the block and still ambulate early after TKA.Level of EvidenceLevel IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.