Accurately Predicting Total Knee Component Size without Preoperative Radiographs.

BACKGROUND: Preoperative templating of total knee arthroplasty (TKA) components can help in choosing appropriate implant size prior to surgery. While long limb radiographs have been shown to be beneficial in assessing alignment, disease state, and previous pathology or trauma, their accuracy for size prediction has not been proven. In an attempt to improve templating precision, surgeons have looked to develop other predictive models for component size determination utilizing patient characteristics. The purpose of this study was to: 1) Identify which patient characteristics influence the tibial and femoral component sizes; 2) Construct models for size prediction; 3) Test the generated models at five different centers; and 4) Compare implant survivorship and patient characteristics between those who did or did not receive an implant within one size of the prediction. MATERIALS AND METHODS: Demographic data was collected on 741 patients (845 knees) as part of a multicenter clinical trial. Correlation between component size and patient demographic data were examined using Pearson coefficients, and significant variables were included into a multivariate-linear-regression model to determine "predicted size." Operative surgeon notes and postoperative radiographs were used to determine "actual size." Predictive equations were constructed for both femoral and tibial components and were tested at five different centers. Implant survivorship and patient characteristics were compared between those who did and did not receive an implant within one size of the prediction. RESULTS: The strongest predictors of component size were height, weight, and gender (p<0.01), followed by ethnicity (p=0.03) and age (p=0.03). Predictive equations were constructed for both tibial and femoral components. The model predicted the component fit within one size in 94% (r2=0.68) and 96% (r2=0.73) of femoral and tibial components. Cases beyond ±1 sizes did not have notable device-specific adverse events with Kaplan-Meier survivorship of 100% at five years. CONCLUSION: Demographic models are an effective tool in component size prediction prior to TKA. This model has implications in reducing the need for preoperative radiographic templating, potentially resulting in increasing surgeon efficiency and possibly reducing hospital implant inventory. This may be particularly important for ambulatory or outpatient surgery centers.

Pseudotumor associated with metal-on-polyethylene total hip arthroplasty.

This case report details the presentation, imaging results, and operative findings of a pseudotumor associated with a press-fit metal-on-polyethylene total hip arthroplasty (THA). An 80-year-old man presented approximately 7 years after undergoing THA with worsening right groin and lateral hip pain with an associated proximal thigh mass. Physical examination demonstrated a tender, large anterolateral thigh mass that was also evident on metal artifact reduction sequence magnetic resonance imaging.An exploratory operative procedure revealed extensive tissue necrosis involving nearly the entire hip capsule, short external rotators, and tendinous portion of the gluteus medius muscle. In addition, marked surface corrosion was discovered about the taper at the head-neck junction of the prosthetic femoral component and the trunnion within the femoral head. The press-fit THA components were solidly fixed. The metallic head was replaced with a ceramic component, and the polyethylene liner was exchanged. The patient had complete resolution of his preoperative symptoms but had persistent problems with dislocations.Although reports of pseudotumor and local soft tissue reactions associated with metal-on-metal THAs have become increasingly ubiquitous in the literature, similar reports involving metal-on-polyethylene THA implants are less common.

Displaced femoral neck fractures: is there a standard of care?

Many factors must be considered in treating displaced femoral neck fractures. For younger patients, ORIF is preferred, whereas arthroplasty is the better option for elderly patients. For institutionalized elderly patients with a low activity level or impaired mental status, the choice should be hemiarthroplasty (either unipolar or bipolar). For high-demand, active patients, evidence continues to mount toward THA as the favored treatment option. However, there is a need for larger clinical trials to demonstrate the most cost-effective way to treat sub-populations of an ever-growing number of patients with displaced femoral neck fractures.

Current practices of AAHKS members in the treatment of adult osteonecrosis of the femoral head.

BACKGROUND: There is currently no standardized protocol for evaluating and treating osteonecrosis of the femoral head in adults in the United States. We sought to understand current treatment practices of a group of surgeons who commonly treat this disease to determine if there was agreement on some aspects of care. METHODS: We designed a two-staged mixed-mode (mailed and faxed) sixteen-question self-administered descriptive survey questionnaire to be sent to all 753 active members of the American Association of Hip and Knee Surgeons (AAHKS). The survey design was based on Dillman's survey research methodology, and the questionnaire included hypothetical clinical scenarios based on the Steinberg classification system. The responses elucidated the opinions and treatment preferences of high-volume arthroplasty surgeons who treat adult patients with osteonecrosis of the femoral head. RESULTS: Of the 753 active members of the AAHKS, 403 (54%) responded to the questionnaire. Total hip replacement was reported to be the most frequent intervention for treatment of postcollapse (Steinberg stage-IIIB, IVB, V, and VI) osteonecrosis; core decompression was reported to be the most commonly offered intervention for symptomatic, precollapse (Steinberg stage-IB and IIB) osteonecrosis. Less frequently offered treatments included nonoperative management, osteotomy, vascularized and non-vascularized bone-grafting, hemiarthroplasty, and arthrodesis. CONCLUSIONS: The care of adults with osteonecrosis of the femoral head varies among American orthopaedic surgeons specializing in hip and knee surgery. A consensus may evolve with a continued concerted effort on the part of interested surgeons, but it will require randomized, controlled, prospective studies of treatment of each stage of the disease and collaborative multicenter studies. LEVEL OF EVIDENCE: Therapeutic Level V.

Treatment of medial compartment arthritis of the knee: a survey of the American Association of Hip and Knee Surgeons.

Medial compartmental arthritis of the knee is a common orthopedic problem. This study surveyed active members of the American Association of Hip and Knee Surgeons on recommended surgical treatment of this condition. A response rate of 30.8% was obtained. One third of respondents (32.9%) reported patient age as the most important factor in determining surgical treatment. Total knee arthroplasty (89.2%) and arthroscopy (87.2%) were the most widely reported surgical treatments. Most respondents (73.7%) rated experience as the primary basis in determining factors for surgical recommendations. Case scenarios revealed age and gender having significant bearing on treatment recommendations. These results suggest that age and degree of deformity are 2 important considerations in surgical treatment of medial compartment arthritis and, among this group of respondents, influence the wide variety of treatment options.

Does shortened length of hospital stay affect total knee arthroplasty rehabilitation outcomes?

Rehabilitation outcomes were compared after primary total knee arthroplasty between patients who participated in a hospital joint arthroplasty program implemented to decrease length of stay and patients who did not. Once inclusion criteria were met, purposive sampling was used to select subjects for retrospective medical records review. Range of motion and Knee Society scores at preoperative and 3-, 6-, and 12-month postoperative intervals were then compared. Preoperatively, there were no significant differences between groups. Program implementation reduced length of hospital stay by a mean of 1.3 days, which resulted in a decreased range of motion at discharge. No significant differences were found between groups postoperatively at all intervals. Primary total knee arthroplasty rehabilitation outcomes were not compromised by reduced length of hospital stay.

Long-term follow-up care recommendations after total hip and knee arthroplasty: results of the American Association of Hip and Knee Surgeons' member survey.

Long-term follow-up care is needed to evaluate and manage hip and knee arthroplasty outcomes, because impending failure may be asymptomatic. All active American Association of Hip and Knee Surgeons' members (N = 682) were surveyed for recommendations for follow-up care type and frequency, radiograph interpretation, and clinical indicators related to follow-up frequency intervals; and to describe reimbursement experiences and practice demographics. The response rate (65.5%, n = 447) established a 95% (+/-3%) confidence interval for the survey results. We found that 80% of respondents recommended annual or biennial orthopaedic clinical and radiographic examinations, with more frequent follow-up times for clinical or radiologic signs of failure, previous revision arthroplasty, previous joint sepsis, and subnormal periprosthetic bone quality. Further research is needed to correlate follow-up care type and frequency with outcomes, complications, and costs.