Short Leg Film Is Sufficient for Postoperative Follow-Up in Total Knee Arthroplasty

The gold standard for evaluating postoperative alignment after total knee arthroplasty (TKA) has been standing AP hip to ankle radiograph. The objective of this study was to determine if the angle between the anatomic axis of the tibia and femur measured on short standard radiographs accurately reflected overall coronal and mechanical alignment from full length knee films. Both full length and short length knee films were retrospectively compared measurements made on from 188 knees in 129 consecutive patients after primary TKA between July 1990 and January 1991. The tibiofemoral angle, distal femur and proximal tibia resection angles, and mechanical alignment were evaluated on the long leg by a blinded observer. The difference in the tibiofemoral angle measured on short and long leg films, 4.4 (+/﹣2.9) vs 5.2 (+/﹣3.0) degrees of valgus, respectively, was statistically significant (p < 0.01). The correlation coefficient between the tibiofemoral angle and mechanical axis was 0.9 (p < 0.01). There was no difference in the distal femur or proximal tibia resection angle measured on short length knee vs long leg films. In conclusion, the tibiofemoral angle measured on short length knee radiographs accurately reflects postoperative alignment. The differences between tibiofemoral angle and the mechanical alignment are highly correlated and equivalent measures of overall alignment.

Predicting Pain in Total and Partial Knee Arthroplasty

Object: Although pain relief is a primary goal of a total knee arthroplasty (TKA) and partial knee arthroplasty (PKA), a significant number of arthroplasty patients experience unexplained pain. This study attempts to determine preoperative or intraoperative factors that may predict pain after knee arthroplasty. Methods: 2585 primary TKAs and 423 PKAs were performed between 1993 and 2013. Infections, loosening, and revision arthroplasty were excluded. Knee Society scores, demographics, component sizes, pre- and postoperative alignment, treatment of the posterior cruciate ligament, range of motion, and diagnosis were analyzed. Statistical analysis utilized repeated measures ANOVA. Results: Significant predictors of increased pain after TKA were pre-operative varus alignment >5° (p = 0.0042), postoperative flexion range of motion 5° (p = 0.0006), small tibial component sizes (p = 0.0080), excision of the posterior cruciate ligament (p = 0.0259), and diagnosis as osteonecrosis (p = 0.0077). Factors not associated with pain included age, body mass index, gender, postoperative alignment and bone quality. For PKA, age was the only factor associated with pain. Conclusions: Six factors were found to be relevant to postoperative pain in TKA. For PKA, reported pain is not associated with any of the same factors, but is associated with age. Surgeons should be aware of these risk factors as we continue to understand pain after total and partial knee arthroplasty.

Changes in Femoral Stem Geometry Reduce Intraoperative Femoral Fracture Rates in Total Hip Replacement

Intraoperative fracture rates in total hip arthroplasty (THA) have been associated with uncemented stems, anterolateral surgical approach, diagnoses other than osteoarthritis, and female gender. The purpose of this study was to investigate if changes in stem design would influence intraoperative fracture rates. 1497 THA with Bi-Metric stems were compared to 1277 THA with Echo Bi-Metric Full Proximal Profile stems and 366 THA with Echo Bi-Metric Reduced Proximal Profile stems. The intraoperative fractures rates were 5.48%, 1.41% and 1.37% for Bi-Metric and Echo Bi-Metric with standard and reduced proximal geometry stems, respectively. Stem survivorship with aseptic loosening as an endpoint was 100% in all cohorts at the final follow-up. We conclude that changes in femoral stem geometry in uncemented THA reduce intraoperative fracture rates while preserving fixation.

Meeting Increased Demand for THA and Follow-Up: An Actuarial Method to Determine Optimal Follow-Up Schedules

If a surgeon performs 200 procedures per year, he/she will have to see 800 patients for follow-up by year 5 and 1300 patients per year by year 10. Normal time constraints make this implausible. When do total hip arthroplasty (THA) patients have the greatest need for follow-up? We reviewed 8331 primary THAs to determine the greatest risk of failure across time. Patients failed with the greatest ratio at 1 year or earlier, followed by 10 and 12 years postoperatively. The median time to failure for all hips was 8.8 years, the average time to failure was 9.2 years, and 75% of failures occurred by 13.0 years. The most common failure mechanisms were due to the cup (5.0%), dislocation (3.2%), cup and stem (1.7%), infection (0.4%), and the stem (0.4%). Based on the most common failure mechanisms, it is recommended to evaluate patients at the 6 months, 1 year, 3 years, 7 years, 10 years, 12 years, 18 years, and 25 years postoperatively.

Early Clinical Outcomes with a 3-D Porous Titanium Acetabular Cup

Cementless acetabular components are associated with a significant incidence of polyethylene wear and secondary osteolysis. 3-dimentional (3-D) porous coating and enhanced shell to a liner fixation are expected to reduce the polyethylene wear and to increase the longevity of an acetabular cup. The authors report the early clinical outcome with a cementless acetabular cup, Regenerex Ringloc+ (Zimmer Biomet, Warsaw, IN) for total hip arthroplasty. Between 2007 and 2013, the registry with 476 hip joints was reviewed retrospectively. There were 210 (48.4%) female and 224 (51.6%) male patients. The average age of the patients at the surgery was 63.9 (± 12.0) years and the average follow-up period was 2.6 years [0.5, 6.5]. At the final follow-up, there was no loosening or cup failure. There were 2 infections, 1 dislocation and 1 liner fracture, resulting in revision hip surgery. Average Harris hip score improved from 53.9 preoperatively to 91.4 postoperatively. The survivorship of Regenerex Ring Loc+ cup and the low complication rate is comparable with previous studies using other 3-D porous metal prostheses. Although this short-term outcome from the institute is very encouraging, a longer follow-up study is required.