Increased Rates of Tibial Aseptic Loosening in Primary Cemented Total Knee Arthroplasty With a Short Native Tibial Stem Design.

BACKGROUND: Emerging evidence has suggested that both obesity and a short, native tibial stem (TS) design may be associated with early aseptic loosening in total knee arthroplasty. The use of short, fully cemented stem extensions may mitigate this risk. As such, we devised a multicenter study to confirm or negate these claims. METHODS: A search of our institutional research databases was done. A minimum 2-year time from index procedure was selected. Cohorts were created according to patient body mass index and the presence (stemmed tibia [ST]) or absence (nonstemmed tibia [NST]) of a short TS extension. Kaplan-Meier survival analyses for aseptic loosening and log-rank tests were done. RESULTS: A total of 1,350 patients were identified (ST = 500, NST = 850). The mean time to the final follow-up in cases without aseptic loosening for the ST cohort was 3.5 years (2.8-6.3) and 5.0 years (2.9-6.3) for the NST cohort (P < 0.001). Kaplan-Meier survival analysis at 6 years was superior for the ST cohort (100%, 98.5%; P = 0.025), and a trend toward superior 5-year survival was observed for body mass index <40 kg/m2 (99.1%, 93.2%; P = 0.066). The mean time to aseptic loosening was 2.4 years (0.9-4.5), with approximately 40% occurring within the first 2 years. CONCLUSIONS: Short, native TS design is associated with early aseptic loosening in primary cemented total knee arthroplasty. This can be mitigated through the use of an ST. More cost-effective solutions include (1) use of implants with longer native stem designs or (2) redesign of short TS implants.

Lack of small tibial component size availability for females in a highly utilized total knee arthroplasty system.

PURPOSE: Surgeons must rely on manufacturers to provide an appropriate distribution of total knee arthroplasty (TKA) sizes. There is a lack of literature regarding current appropriateness of tibial sizing schemes according to sex. As such, a study was devised assessing the adequacy of off-the-shelf tibial component size availability according to sex. METHODS: A search was conducted to identify all primary TKAs between July 2012 and June 2019 performed using a single implant. Baseline patient characteristics were collected (age, weight, height, BMI, and race). Two cohorts were created according to patient sex. Tibial sizes for each cohort were collected. Tibial component bar graph and histogram were created according to component sizes. Skewness and kurtosis were calculated for each distribution. Overhang was noted and measured radiographically. RESULTS: A total of 864 patients were identified, 38.7% males and 61.3% females. Most patients were Caucasian, and BMI was similar between cohorts. Tibial size distribution for males was as follows: 0.3% C, 4.8% D, 16.5% E, 40.1% F, 31.4% G, 6.9% H. Tibial size distribution for females was as follows: 30.8% C, 42.8% D, 23.0% E, 2.6% F, 0.8% G, 0.0% H. Histograms and normal curves demonstrated a fairly symmetric distribution of sizes for males (skewness = - 0.31, kurtosis = - 0.03). The distribution for females was positively skewed (skewness = 0.57, kurtosis = 0.12). Overall, overhang was noted in 16.6% of all size C tibias. CONCLUSIONS: The results of this study highlight an implant-specific discrepancy in size availability affecting female patients which could result in inferior outcomes. The authors urge manufacturers to critically assess current implant size distribution availability to ensure both genders are adequately, and equally represented. LEVEL OF EVIDENCE: IV.

Clinical Outcomes of Intermediate-Length Cephalomedullary Nails for Intertrochanteric Femur Fracture Repair in Older Adults.

INTRODUCTION: Hip fracture is a major cause of morbidity and mortality in older adults. Intertrochanteric hip fractures often are treated surgically using cephalomedullary nails (CMN), in either a short or long length. Their outcomes are documented in the literature; however, outcomes of the intermediate-length CMN have not been well described. METHODS: A retrospective review was conducted of older adults with intertrochanteric hip fractures that were treated with cephalomedullary nail fixation using an intermediate-length (235 mm Synthes Trochanteric Fixation® nail or 240 mm Stryker Gamma 3®) nail. Outcome data were collected during the inpatient stay and 16 months post-operatively. RESULTS: Seventy-seven patients met inclusion criteria and were reviewed during inpatient stay; however, only 42 had documented post-operative outcomes. Of those, two patients died post-discharge and were not included in the 16-month follow-up. Comparison of results to published literature suggested that intermediate-length nails are comparable to short-length nails with regard to time in the operating room and estimated blood loss. The rate of blood transfusion was lower and length of hospital stay was shorter than in comparable studies of both short- and long-length nails. There were no post-operative peri-prosthetic fractures in the 16-month follow-up. This rate was lower than published rates for short and long nails. The hardware failure rate (3/42, 7.1%) of intermediate-length nails was higher than comparison studies of both short- and long-length nails. CONCLUSION: Patient outcomes for intermediate-length nails were similar to outcomes of shorter length nails. Utilization of the intermediate-length nail appears to be an effective treatment option for repair of intertrochanteric femur fractures. However, direct comparison is difficult since peri-prosthetic fracture rate may increase over time and nail length and hardware failure are not defined consistently in the literature. Further study is needed with a larger sample size followed over a longer period of time to confirm our findings.