Faculty Bibliography

PURPOSE: There are limited studies examining the long-term survivorship for the current generation of metal-on-metal hip resurfacing (MOMHR) implants in the young male population, and fewer studies have been published on prospectively collected outcomes data for total hip resurfacing in the USA. The purpose of this study was to demonstrate the efficacy of MOMHR in comparison with total hip arthroplasty (THA) using validated outcome measures, survivorship and complication rates. METHODS: The study prospectively followed 136 implants in 123 male patients <65 years, all with a primary diagnosis of osteoarthritis and similar comorbidities as determined by the American Society of Anesthesiologists (ASA) score. A single-surgeon cohort of 89 MOMHRs was compared with a similar cohort of 47 THAs. Outcomes were prospectively assessed with the Short-Form Health Survey of 12 questions (SF-12) and Western Ontario and McMaster Universities (WOMAC) questionnaires pre- and postoperatively at yearly intervals. Minimum follow-up was two years, and average follow-up was 3.9 years. RESULTS: Diagnosis, body mass index (BMI), American Association of Anesthesiologists (ASA) and pre-operative pain and function scores were not significantly different between groups. There was no difference in SF-12 scores postoperatively. At one and two years postoperatively, the MOMHR group had better WOMAC scores than the THA group, but no difference was seen at three to five years postoperatively. There were no revisions in either group over the study period. CONCLUSIONS: This study demonstrated good results for hip resurfacing in men <65 years five years postoperatively and similar function to THA patients.

BACKGROUND: Intertrochanteric hip fractures are a major source of morbidity and financial burden, accounting for 7% of osteoporotic fractures and costing nearly $6 billion annually in the United States. Traditionally, "stable" fracture patterns have been treated with an extramedullary sliding hip screw whereas "unstable" patterns have been treated with the more expensive intramedullary nail. The purpose of this study was to identify parameters to guide cost-effective implant choices with use of decision-analysis techniques to model these common clinical scenarios. METHODS: An expected-value decision-analysis model was constructed to estimate the total costs and health utility based on the choice of a sliding hip screw or an intramedullary nail for fixation of an intertrochanteric hip fracture. Values for critical parameters, such as fixation failure rate, were derived from the literature. Three scenarios were evaluated: (1) a clearly stable fracture (AO type 31-A1), (2) a clearly unstable fracture (A3), or (3) a fracture with questionable stability (A2). Sensitivity analysis was performed to test the validity of the model. RESULTS: The fixation failure rate and implant cost were the most important factors in determining implant choice. When the incremental cost for the intramedullary nail was set at the median value ($1200), intramedullary nailing had an incremental cost-effectiveness ratio of $50,000/quality-adjusted life year when the incremental failure rate of sliding hip screws was 1.9%. When the incremental failure rate of sliding hip screws was >5.0%, intramedullary nails dominated with lower cost and better health outcomes. The sliding hip screw was always more cost-effective for A1 fractures, and the intramedullary nail always dominated for A3 fractures. As for A2 fractures, the sliding hip screw was cost-effective in 70% of the cases, although this was highly sensitive to the failure rate. CONCLUSIONS: Sliding hip screw fixation is likely more cost-effective for stable intertrochanteric fractures (A1) or those with questionable stability (A2), whereas intramedullary nail fixation is more cost-effective for reverse obliquity fractures (A3). These conclusions are highly sensitive to the fixation failure rate, which was the major influence on the model results.

Lesser-trochanter-to-center-of-femoral-head-distance (LTCHD) is commonly used in hip reconstruction. Demographic and radiographic variables were analyzed to predict the LTCHD and femoral head size (FHS). Two hundred twenty six patients after hip arthroplasty and 136 patients after hip hemiarthroplasty (HA) were retrospectively reviewed. Five variables significantly affected the LTCHD and four affected the FHS. For LTCHD, it was relative neck length (RNL), gender, height, race, age and weight. For FHS it was gender, height, age and race. The average predicted LTCHD was within 2.86 mm, and the FHS was 1.63 +/- 1.10mm of the intra-operative measurements. By using our regression formulas the LTCHD and FHS can be calculated preoperatively to help improve precision in leg length and offset reconstruction.

AIM: To track the short-term neck narrowing changes in Birmingham metal-on-metal hip resurfacing (MOMHR) patients. METHODS: Since 2001, the Center for Hip and Knee Replacement started a registry to prospectively collect data on hip and knee replacement patients. From June 2006 to October 2008, 139 MOMHR were performed at our center by two participate surgeons using Birmingham MOMHR prosthesis (Smith Nephew, United States). It is standard of care for patients to obtain low, anteriorposterior (LAP) pelvis radiographs immediately after MOMHR procedure and then at 3 mo, 1 year and 2 year follow up office visits. Inclusion criteria for the present study included patients who came back for follow up office visit at above mentioned time points and got LAP radiographs. Exclusion criteria include patients who missed more than two follow up time points and those with poor-quality X-rays. Two orthopaedic residency trained research fellows reviewed the X-rays independently at 4 time points, i.e., immediate after surgery, 3 mo, 1 year and 2 year. Neck-to-prosthesis ratio (NPR) was used as main outcome measure. Twenty cases were used as subjects to identify the reliability between two observers. An intraclass correlation coefficient at 0.8 was considered as satisfied. A paired t-test was used to evaluate the significant difference between different time points with P < 0.05 considered to be statistically significant. RESULTS: The mean NPRs were 0.852 +/- 0.056, 0.839 +/- 0.052, 0.835 +/- 0.051, 0.83 +/- 0.04 immediately, 3 mo, 1 year and 2 years post-operatively respectively. At 3 mo, NPR was significantly different from immediate postoperative X-ray (P < 0.001). There was no difference between 3 mo and 1 year (P = 0.14) and 2 years (P = 0.53). Femoral neck narrowing (FNN) exceeding 10% of the diameter of the neck was observed in only 4 patients (5.6%) at two years follow up. None of these patients developed a femoral neck fracture (FNF). CONCLUSION: Femoral neck narrowing after MOMHR occurred as early as 3 mo postoperatively, and stabilized thereafter. Excessive FNN was not common in patients within the first two years of surgery and was not correlated with risk of FNF.

Cephalomedullary devices (CMN) have become an increasingly popular for treatment of intertrochanteric hip fractures compared to sliding hip screw and side plate (SHS) devices. Failed fixation is often treated with conversion total hip arthroplasty (THA). We performed a multi-institutional study in which 60 patients with SHS devices and 31 patients with CMN devices were converted to THA. Harris Hip Score improved from 41.6 preoperatively to 83.6 at final follow-up in the SHS group and from 41.6 to 78.6 in the CMN group, with no significant difference between the groups (P=0.23). However, the complication rate in converted CMN patients was significantly higher at 41.9% compared with 11.7% (P=0.001) in converted SHS patients. Prior fixation with CMN may be associated with significantly higher complication rates during conversion.

BACKGROUND: Intraarticular hip disease is commonly acknowledged as a cause of ipsilateral knee pain. However, this is based primarily on observational rather than high-quality evidence-based studies, and it is unclear whether ipsilateral knee pain improves when hip disease has been treated. QUESTIONS/PURPOSES: We asked whether (1) hip disease was associated with preoperative ipsilateral knee pain and (2) ipsilateral knee pain would improve after hip arthroplasty. PATIENTS AND METHODS: We retrospectively assessed knee pain in 255 patients who underwent hip arthroplasties between 2006 and 2008. The WOMAC pain score of each joint was the primary outcome measure, which was obtained prospectively before surgery and at 3 months and 1 year postoperatively. Of the 255 patients, 245 (96%) had followup data obtained at 3 months or 1 year. RESULTS: Preoperatively, ipsilateral knee pain was observed more frequently than contralateral knee pain (55% versus 18%). Preoperative ipsilateral knee pain scores were worse than contralateral knee pain scores (mean, 80 versus 95). Ipsilateral knee pain improved at 3 months and 1 year. When compared with the scores for contralateral knee pain at 3 months (95) and 1 year (96), there were no differences between knees. CONCLUSIONS: Our observations suggest hip disease is associated with ipsilateral knee pain and that it improves after hip arthroplasty. This should be considered during preoperative evaluation for patients with hip and knee pain. LEVEL OF EVIDENCE: Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

The purpose of this study was to compare short-term clinical outcomes between total hip arthroplasty (THA) and total knee arthroplasty (TKA) patient cohorts, adjusting for confounding variables including age, sex, body mass index, operative time, length of stay, and preoperative Western Ontario and McMaster Universities and 12-Item Short-Form Health Survey. A total of 349 patients who met inclusion and exclusion criteria created 2 cohorts: THA, 194, and TKA, 155, for statistical analysis via multiple regression and analysis of covariance measures. Outcome measures included Western Ontario and McMaster Universities and 12-Item Short-Form Health Survey data, collected prospectively at baseline and 2 years of follow-up. The current study showed that baseline characteristics of TKA patients have more factors with negative effect on postoperative outcome than THA. However, despite controlling for the possible confounding effect of these variables, THA patients experienced a significantly better functional outcome than TKA patients.

AIM: To identify factors that affect patient response rates to preoperative functional surveys in hip and knee arthroplasty patients. METHODS: From May 2008 to March 2009, 247 patients were scheduled more than 4 wk in advance for hip or knee arthroplasty by one of two participating surgeons at our center. A personalized questionnaire comprised of the Short Form 12 (SF-12) and Western Ontario and McMaster Universities (WOMAC) Index was mailed to patients at random time points ranging from 7 to 101 d prior to surgery. Nine independent factors were documented prospectively, including age, gender, ethnicity, marital status, type of surgery, surgeon, days prior to surgery (DPS) of survey mailing, WOMAC score and SF-12 score. The date of the completed survey receipt was also documented. For non-responders, the surveys were completed with the research team at the hospital upon admission. Multivariate regression and chi(2) analysis were performed with Statistical Analysis Software software. RESULTS: DPS was the only factor that affected patient response. Mailing surveys 26 d to 31 d prior to surgery dates led to a peak response rate of 80% that was significantly higher (P < 0.023) than response rates for patients who were mailed their surveys /= 32 d prior to surgery (55%). No other factors, including preoperative WOMAC and SF-12 scores, significantly influenced response behavior. CONCLUSION: The DPS was independently the most significant predictor of response rates for pre-operative functional data among patients scheduled for hip and knee arthroplasty.

Total knee arthroplasty (TKA) can lead to substantial blood loss. To avoid the high costs of autologous blood predonation programs and efficiently allocate limited blood resources, we sought to identify preoperative and intraoperative factors associated with allogeneic blood transfusion (AllTx) after primary TKA and, subsequently, develop a model to predict patients who will require AllTx. We analyzed 31 independent variables in 644 primary unilateral TKAs without autologous blood predonation for requirement of AllTx. Seventy-one procedures (11.0%) required AllTx. Age, comorbid anemia, preoperative hemoglobin concentration, and surgical time were significant predictors for requiring AllTx. When applied to an independent cohort, our model for predicting the need for AllTx after TKA was 90% sensitive and 52.5% specific.