Are There Sex Differences in Knee Cartilage Composition and Walking Mechanics in Healthy and Osteoarthritis Populations?

Background

Women are at a greater risk for knee osteoarthritis (OA), but reasons for this greater risk in women are not well understood. It may be possible that differences in cartilage composition and walking mechanics are related to greater OA risk in women.

Questions/purposes

(1) Do women have higher knee cartilage and meniscus T_1ρ than men in young healthy, middle-aged non-OA and OA populations? (2) Do women exhibit greater static and dynamic (during walking) knee loading than men in young healthy, middle-aged non-OA and OA populations?

Methods

Data were collected from three cohorts: (1) young active (< 35 years) (20 men, 13 women); (2) middle-aged (≥ 35 years) without OA (Kellgren-Lawrence [KL] grade < 2) (43 men, 65 women); and (3) middle-aged with OA (KL > 1) (18 men, 25 women). T_1ρ and T₂ relaxation times for cartilage in the medial knee, lateral knee, and patellofemoral compartments and medial and lateral menisci were quantified with 3.0-T MRI. A subset of the participants underwent three-dimensional motion capture during walking for calculation of peak knee flexion and adduction moments, flexion and adduction impulses, and peak adduction angle. Differences in MR, radiograph, and gait parameters between men and women were compared in the three groups separately using multivariate analysis of variance.

Results

Women had higher lateral articular cartilage T_1ρ (men = 40.5 [95% confidence interval {CI}, 38.8–42.3] ms; women = 43.3 [95% CI, 41.9–44.7] ms; p = 0.017) and patellofemoral T_1ρ (men = 44.4 [95% CI, 42.6–46.3] ms; women = 48.4 [95% CI, 46.9–50.0] ms; p = 0.002) in the OA group; and higher lateral meniscus T_1ρ in the young group (men = 15.3 [95% CI, 14.7–16.0] ms; women = 16.4 [95% CI, 15.6–17.2] ms; p = 0.045). The peak adduction moment in the second half of stance was lower in women in the middle-aged (men = 2.05 [95% CI, 1.76–2.34] %BW*Ht; women = 1.66 [95% CI, 1.44–1.89] %BW*Ht; p = 0.037) and OA (men = 2.34 [95% CI, 1.76–2.91] %BW*Ht; women = 1.42 [95% CI, 0.89–1.94] %BW*Ht; p = 0.022) groups. Static varus from radiographs was lower in women in the middle-aged (men = 178° [95% CI, 177°–179°]; women = 180° [95% CI, 179°–181°]; p = 0.002) and OA (men = 176° [95% CI, 175°–178°]; women = 180° [95% CI, 179°–181°]; p < 0.001) groups. Women had lower varus during walking in all three groups (young: men = 4° [95% CI, 3°–6°]; women = 2° [95% CI, 0°–3°]; p = 0.013; middle-aged: men = 2° [95% CI, 1°–3°]; women = 0° [95% CI, −1° to 1°]; p = 0.015; OA: men = 4° [95% CI, 2°–6°]; women = 0° [95% CI, −2° to 2°]; p = 0.011). Women had a higher knee flexion moment (men = 4.24 [95% CI, 3.58–4.91] %BW*Ht; women 5.40 [95% CI, 4.58–6.21] %BW*Ht; p = 0.032) in the young group.

Conclusions

These data demonstrate differences in cartilage composition and gait mechanics between men and women in young healthy, middle-aged healthy, and OA cohorts. Considering the cross-sectional nature of the study, longitudinal research is needed to investigate if these differences in cartilage composition and walking mechanics are associated with a greater risk of lateral tibiofemoral or patellofemoral OA in women. Future studies should also investigate the relative risk of lateral versus medial patellofemoral cartilage degeneration risk in women compared with men.

Level of Evidence

Level III, retrospective study.     

Low Albumin Levels,More Than Morbid Obesity,Are Associated With Complications After TKA

Background

Morbid obesity and malnutrition are thought to be associated with more frequent perioperative complications after TKA. However, morbid obesity and malnutrition often are co-occurring conditions. Therefore it is important to understand whether morbid obesity, malnutrition, or both are independently associated with more frequent perioperative complications. In addition, assessing the magnitude of an increase in complications and whether these complications are major or minor is important for both conditions.

Questions/purposes

We asked: (1) Is morbid obesity independently associated with more frequent major perioperative complications after TKA? (2) Are major perioperative complications after TKA more prevalent among patients with a low serum albumin?

Methods

The National Surgical Quality Improvement Program (NSQIP) database was analyzed from 2006 to 2013. Patients were grouped as morbidly obese (BMI ≥ 40 kg/m²) or nonmorbidly obese (BMI ≥ 18.5 kg/m² to < 40 kg/m²), or by low serum albumin (serum albumin level < 3.5 mg/dL) or normal serum albumin (serum albumin level ≥ 3.5 mg/dL). The study cohort included 77,785 patients, including 35,573 patients with a serum albumin level of 3.5 g/dL or greater and 1570 patients with a serum albumin level less than 3.5 g/dL. Therefore, serum albumin levels were available for only 37,173 of the 77,785 of the patients (48%). There were 66,382 patients with a BMI between 18.5 kg/m² and 40 kg/m² and 11,403 patients with a BMI greater than 40 kg/m². Data were recorded on patient mortality along with 21 complications reported in the NSQIP. We also developed three composite complication variables to represent risk of any infections, cardiac or pulmonary complications, and any major complications. For each complication, multivariate logistic regression analysis was performed. Independent variables included patient age, sex, race, BMI, American Society of Anesthesiologists classification, year of surgery, and Charlson comorbidity index score.

Results

Mortality was not increased in the morbidly obese group (0.14% vs 0.14%; p = 0.942). Patients who were morbidly obese were more likely to have progressive renal insufficiency (0.30% vs 0.10%; odds ratio [OR], 2.47; 95% CI, 1.27–4.29; p < 0.001), superficial infection (1.07% vs 0.55%; OR, 1.87; 95% CI, 1.39–2.51; p < 0.001), and sepsis (0.36% vs 0.23%; OR, 1.70; 95% CI, 1.04–2.53; p = 0.034) compared with patients who were not morbidly obese. Patients who were morbidly obese were less likely to require blood transfusion (8.68% vs 12.06%; OR, 0.70; 95% CI, 0.63–0.77; p < 0.001) compared with patients who were not morbidly obese. Morbid obesity was not associated with any of the other 21 perioperative complications recorded in the NSQIP database. With respect to the composite complication variables, patients who were morbidly obese had an increased risk of any infection (3.31% vs 2.41%; OR, 1.38; 95% CI, 1.16–1.64; p < 0.001) but not for cardiopulmonary or any major complication. The group with low serum albumin had higher mortality than the group with normal serum albumin (0.64% vs 0.15%; OR, 3.17; 95% CI, 1.58–6.35; p = 0.001). Patients in the low serum albumin group were more likely to have a superficial surgical site infection (1.27% vs 0.64%; OR, 1.27; 95% CI, 1.09–2.75; p = 0.020); deep surgical site infection (0.38% vs 0.12%; OR, 3.64; 95% CI, 1.54–8.63; p = 0.003); organ space surgical site infection (0.45% vs 0.15%; OR, 2.71; 95% CI, 1.23–5.97; p = 0.013); pneumonia (1.21 vs 0.29%; OR, 3.55; 95% CI, 2.14–5.89; p < 0.001); require unplanned intubation (0.51% vs 0.17%, OR, 2.24; 95% CI, 1.07–4.69; p = 0.033); and remain on a ventilator more than 48 hours (0.38% vs 0.07%; OR, 4.03; 95% CI, 1.64–9.90; p = 0.002). They are more likely to have progressive renal insufficiency (0.45 % vs 0.12%; OR, 2.71; 95% CI, 1.21–6.07; p = 0.015); acute renal failure (0.32% vs 0.06%; OR, 5.19; 95% CI, 1.96–13.73; p = 0.001); cardiac arrest requiring cardiopulmonary resuscitation (0.19 % vs 0.12%; OR, 3.74; 95% CI, 1.50–9.28; p = 0.005); and septic shock (0.38% vs 0.08%; OR, 4.4; 95% CI, 1.74–11.09; p = 0.002). Patients in the low serum albumin group also were more likely to require blood transfusion (17.8% vs 12.4%; OR, 1.56; 95% CI, 1.35–1.81; p < 0.001). In addition, among the three composite complication variables, any infection (5.0% vs 2.4%; OR, 2.0; 95% CI, 1.53–2.61; p < 0.001) and any major complication (2.4% vs 1.3%; OR, 1.41; 95% CI, 1.00–1.97; p = 0.050) were more prevalent among the patients with low serum albumin. There was no difference for cardiopulmonary complications.

Conclusions

Morbid obesity is not independently associated with the majority of perioperative complications measured by the NSQIP and was associated only with increases in progressive renal insufficiency, superficial surgical site infection, and sepsis among the 21 perioperative variables measured. However, low serum albumin was associated with increased mortality and multiple additional major perioperative complications after TKA. Low serum albumin, more so than morbid obesity, is associated with major perioperative complications. This is an important finding, as low serum albumin may be more modifiable than morbid obesity in patients who are immobile or have advanced knee osteoarthritis.

Level of Evidence

Level III, prognostic study.     

Femoroacetabular Impingement: Prevalent and Often Asymptomatic in Older Men: The Osteoporotic Fractures in Men Study

Background

The epidemiology of femoroacetabular impingement (FAI) is important but incompletely understood, because most reports arise from symptomatic populations. Investigating the prevalence of FAI in a community-based cohort could help us better understand its epidemiology and in particular the degree to which it might or might not be associated with hip pain.

Questions/purposes

The purposes of this study were (1) to evaluate the proportion of older (≥ 65 years of age) men with morphologic abnormalities consistent with FAI; and (2) to assess the association of the morphologic abnormalities with prevalent radiographic hip osteoarthritis (OA) and hip pain.

Methods

Anteroposterior radiographs were obtained in 4140 subjects (mean age ± SD, 77 ± 5 years) from the Osteoporotic Fractures in Men study. We assessed each hip for cam, pincer, and mixed FAI types using validated radiographic definitions. Both intra- and interobserver reproducibility were > 0.9. Radiographic hip OA was assessed by an expert reader (intraobserver reproducibility, 0.7–0.8) using validated methods, and summary grades of 2 or greater (on a scale from 0 to 4) were used to define radiographic hip OA. Covariates including hip pain in the last 30 days were collected by questionnaires that were answered by all patients included in this report. Logistic regressions with generalized estimating equations were performed to evaluate the association of radiographic features of FAI and arthrosis.

Results

Pincer, cam, or mixed types of radiographic FAI had a prevalence of 57% (1748 of 3053), 29% (886 of 3053), and 14% (419 of 3053), respectively, in this group of older men. Both pincer and mixed types of FAI were associated with arthrosis but not with hip pain (odds ratio [OR], 1.63; 95% confidence interval [CI], 1.25–2.13; p < 0.001 for pincer and OR, 2.49; 95% CI, 1.65–3.76; p < 0.001 for mixed type). Patients with hips characterized by cam-type FAI had slightly reduced hip pain without the presence of arthrosis compared with hips without FAI (OR, 0.82; 95% CI, 0.68–0.99; p = 0.037). A center-edge angle > 39° and a caput-collum-diaphyseal angle < 125° were associated with arthrosis (OR, 1.53; 95% CI, 1.22–1.94; p < 0.001 and OR, 2.09; 95% CI, 1.24–3.51; p = 0.006, respectively), but not with hip pain (OR, 0.89; 95% CI, 0.77–1.03; p < 0.108 and OR, 0.99; 95% CI, 0.67–1.45; p = 0.945, respectively). An impingement angle < 70° was associated with less hip pain compared with hips with an impingement angle ≥ 70° (OR, 0.76; 95% CI, 0.61–0.95; p = 0.015).

Conclusions

FAI is common in older men and represents more of an anatomic variant rather than a symptomatic disease. This finding should raise questions on how age, activities, and this anatomic variant each contribute to result in symptomatic disease.

Level of Evidence

Level III, prognostic study.     

Morbidity and Readmission After Open Reduction and Internal Fixation of Ankle Fractures Are Associated With Preoperative Patient Characteristics

Background

Ankle fractures are common and can be associated with severe morbidity. Risk factors for short-term adverse events and readmission after open reduction and internal fixation (ORIF) of ankle fractures have not been fully characterized.

Questions/purposes

The purpose of our study was to determine patient rates and risk factors for (1) any adverse event; (2) severe adverse events; (3) infectious complications; and (4) readmission after ORIF of ankle fractures.

Methods

Patients who underwent ORIF for ankle fracture from 2005 to 2012 were identified in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP^®) database using International Classification of Diseases, 9^th Revision and Current Procedural Terminology codes. Patients with missing perioperative data were excluded from this study. Patient characteristics were tested for association with any adverse event, severe adverse events, infectious complications, and readmission using bivariate and multivariate logistic regression analyses.

Results

Of the 4412 patients identified, 5% had an adverse event. Any adverse event was associated with insulin-dependent diabetes mellitus (IDDM; odds ratio [OR], 2.05; 95% confidence interval [CI], 1.35–3.1; p = 0.001), age ≥ 60 years (OR, 1.97; 95% CI, 1.22–3.2; p = 0.006), American Society of Anesthesiologists classification ≥ 3 (OR, 1.69; 95% CI, 1.2–2.37; p = 0.002), bimalleolar fracture (OR, 1.6; 95% CI, 1.08–2.37; p = 0.020), hypertension (OR, 1.47; 95% CI, 1.04–2.09; p = 0.031), and dependent functional status (OR, 1.47; 95% CI, 1.02–2.14; p = 0.040) on multivariate analysis. Severe adverse events occurred in 3.56% and were associated with ASA classification ≥ 3 (OR, 2.01; p = 0.001), pulmonary disease (OR, 1.9; p = 0.004), dependent functional status (OR, 1.8; p = 0.005), and hypertension (OR, 1.65; p = 0.021). Infectious complications occurred in 1.75% and were associated with IDDM (OR, 3.51; p < 0.001), dependent functional status (OR, 2.4; p = 0.002), age ≥ 60 years (OR, 2.28; p = 0.028), and bimalleolar fracture (OR, 2.19; p = 0.030). Readmission occurred in 3.17% and was associated with ASA classification ≥ 3 (OR, 2.01; p = 0.017).

Conclusions

IDDM was associated with an increased rate of adverse events after ankle fracture ORIF, whereas noninsulin-dependent diabetes mellitus was not. IDDM management deserves future study, particularly with respect to glycemic control, a potential confounder that could not be assessed with the ACS-NSQIP registry. Increased ASA class was associated with readmission, and future prospective investigations should evaluate the effectiveness of increasing the discharge threshold, discharging to extended-care facilities, and/or home nursing evaluations in this at-risk population.

Level of Evidence

Level III, prognostic study.

Electronic supplementary material

The online version of this article (doi:10.1007/s11999-014-4005-z) contains supplementary material, which is available to authorized users.     

Functional Impairment Is a Risk Factor for Knee Replacement in the Multicenter Osteoarthritis Study

Background

Debilitating pain associated with knee osteoarthritis (OA) often leads patients to seek and complete total knee arthroplasty (TKA). To date, few studies have evaluated the relation of functional impairment to the risk of TKA, despite the fact that OA is associated with functional impairment.

Questions/purposes

The purpose of our study was to (1) evaluate whether function as measured by WOMAC physical function subscale was associated with undergoing TKA; and (2) whether any such association varied by sex.

Methods

The National Institutes of Health-funded Multicenter Osteoarthritis Study (MOST) is an observational cohort study of persons aged 50 to 79 years with or at high risk of symptomatic knee OA who were recruited from the community. All eligible subjects with complete data were included in this analysis. Our study population sample consisted of 2946 patients with 5796 knees; 1776 (60%) of patients were women. We performed a repeated-measures analysis using baseline WOMAC physical function score to predict the risk of TKA from baseline to 30 months and WOMAC score at 30 months to predict risk of incident TKA from 30 months to 60 months. We used generalized estimating equations to account for the correlation between two knees within an individual and across the two periods. We calculated relative risk (RR) of TKA over 30 months by WOMAC function using a score of 0 to 5 as the referent in multiple binomial regressions with log link.

Results

Those with the greatest functional impairment (WOMAC scores 40–68; 62 TKAs in 462 knee periods) had 15.5 times (95% confidence interval [CI], 7.6–31.8; p < 0.001) the risk of undergoing TKA over 30 months compared with the referent group (12 TKAs in 3604 knee periods), adjusting for basic covariates, and 5.9 times (95% CI, 2.8–12.5; p < 0.001) the risk after further adjusting for knee pain severity. At every level of functional limitation, the RR for TKA for women was higher than for men, but interaction with sex did not reach significance after adjustment for covariates including ipsilateral pain (p = 0.138).

Conclusions

Baseline physical function appears to be an important element in patients considering TKA. Future studies should examine whether interventions to improve function can reduce the need for TKA.

Level of Evidence

Level III, observational cohort study.     

Acetate Templating on Digital Images Is More Accurate Than Computer-based Templating for Total Hip Arthroplasty

Background

Templating is an important aspect of preoperative planning for total hip arthroplasty and can help determine the size and positioning of the prosthesis. Historically, templating has been performed using acetate templates over printed radiographs. As a result of the increasing use of digital imaging, surgeons now either obtain additional printed radiographs solely for templating purposes or use specialized digital templating software, both of which carry additional cost.

Questions/purposes

The purposes of this study was to compare acetate templating of digitally calibrated images on an LCD monitor to digital templating in terms of (1) accuracy; (2) reproducibility; and (3) time efficiency.

Methods

Acetate onlay templating was performed directly over digital radiographs on an LCD monitor and was compared with digital templating. Five separate observers participated in this study templating on 52 total hip arthroplasties. For the acetate templating, the digital images were magnified to the scaled reference on the templates provided by the manufacturer (ratio 1.2:1) before templating using a 25-mm marker as a reference. Both the acetate and digital templating results were then compared with the actual implanted components to determine accuracy. Interobserver and intraobserver variability was determined by an intraclass correlation coefficient. Observers recorded time to complete templating from the time of complete upload of patients’ imaging onto the system to completion of templating.

Results

Both acetate and digital templates demonstrated moderate accuracy in predicting within one size of the eventual implanted acetabular cup (77% [199 of 260]; 70% [181 of 260], respectively; p = 0.050; 95% confidence interval [CI], 0.058–0.32), whereas acetate templating was better at predicting the femoral stem compared to digital templating (75% [195 of 260]; 60% [155 of 260], respectively; p < 0.001; 95% CI, 0.084–0.32). Acetate templating showed moderate to substantial interobserver agreement (cup intraclass correlation coefficient [ICC] = 0.55; 95% CI, 0.14–0.86; femoral ICC = 0.75; 95% CI, 0.39–0.95) and both methods showed almost perfect intraobserver agreement in reproducibility (acetate cup ICC = 0.82; 95% CI, 0.66–0.97; acetate femoral ICC = 0.86; 95% CI, 0.74–0.97; digital cup ICC = 0.82; 95% CI, 0.68–0.97; digital femoral ICC = 0.88; 95% CI, 0.77–1.0). Acetate templating could be performed more quickly (acetate mean 119 seconds; range, 37–220 seconds versus 154 seconds; range, 73–343 seconds; p < 0.001).

Conclusions

Acetate onlay templating on digitally calibrated images can be a reliable substitute for digital templating using specialized software. It is quicker to perform and much less expensive. Hospitals and practices need not purchase expensive software, particularly at lower volume centers.

Level of Evidence

Level III, diagnostic study.     

What Host Factors Affect Aseptic Loosening After THA and TKA?

Background

Aseptic loosening is the most common cause for revisions after lower-extremity total joint arthroplasties, however studies differ regarding the degree to which host factors influence loosening.

Questions/purpose

We performed a systematic review to determine which host factors play a role in the development of clinical and/or radiographic failure from aseptic loosening after (1) THA and (2) TKA.

Methods

Two searches on THA and TKA, respectively, using four electronic databases (EMBASE, CINAHL Plus, PubMed, and Scopus) were conducted. We identified a total of 209 reports that encompassed nine potential host factors affecting aseptic loosening. Inclusion criteria for consideration of scientific clinical reports were that 20 or more patients were involved, with more than 1-year followup, with at least three studies pertaining to each factor, and at least six of the Methodological Index for Non-randomized Studies criteria met, and with raw data for odds ratio (OR) calculations. Twenty-one studies (16 THA studies with 45,779 hips and five TKA studies with 288 knees, respectively) were used to calculate weighted OR and CIs (using the random effects theory) and study heterogeneity for four different host factors in THAs (male sex, high activity level, obesity defined as BMI ≥ 30 kg/m², and current or former tobacco use) and one factor in TKA (BMI ≥ 30 kg/m²), which were placed in a forest plot.

Results

For THA, male sex (OR, 1.39; 95% CI, 1.22–1.58; p = 0.001) and high activity level (University of California Los Angeles [UCLA] activity score ≥ 8 points; OR, 4.24; 95% CI, 2.46–7.31; p = 0.001) were associated with aseptic loosening. However, obesity (OR, 1.01; 95% CI, 0.73–1.40; p = 0.96), and tobacco use (OR, 1.96; 95% CI, 0.43–8.97; p = 0.39) were not associated with an increased risk of aseptic loosening after THA with the numbers available. For TKA, we found no host factors associated with loosening. In particular, obesity (BMI ≥ 30 kg/m²) was not associated with aseptic loosening with the numbers available (OR, 2.28; 95% CI, 0.60–8.62; p = 0.22).

Conclusions

Patients undergoing a lower-extremity total joint arthroplasty who engage in impact sports should be counseled regarding their potential increased risk of aseptic loosening; however, given the weak evidence available, we believe that higher-level studies are necessary to clearly define the risk factors, particularly with newer-generation constructs.

Level of Evidence

Level IV, therapeutic study.     

Biomechanical Outcomes of Bridge-enhanced Anterior Cruciate Ligament Repair Are Influenced by Sex in a Preclinical Model

Background

Despite the well-established role of sex on the anterior cruciate ligament (ACL) injury risk, its effects on ACL surgical outcomes remain controversial. This is particularly critical when developing novel surgical techniques to treat the injury because there are limited data existing on how these procedures will respond in each sex. One such approach is bridge-enhanced ACL repair, in which primary suture repair of the ACL is augmented with a bioactive scaffold saturated with autologous blood. It has shown comparable biomechanical outcomes to ACL reconstruction in preclinical models.

Questions/purposes

We asked (1) whether sex affects the biomechanical outcomes of bridge-enhanced ACL repair; and (2) if suture type (absorbable or nonabsorbable), used to repair the torn ACL, can minimize the potential sex discrepancies in outcomes after 15 weeks of healing in a large animal preclinical model.

Methods

Seventeen (eight males, nine females) Yorkshire pigs (Parson’s Farms, Hadley, MA, USA) underwent bilateral ACL transection and received bridge-enhanced ACL repair with an absorbable suture (n = 17) on one side and with a nonabsorbable suture (n = 17) on the other side. The leg receiving the absorbable suture was randomized within each animal. ACL structural properties and AP knee laxity for each knee were measured after 15 weeks of healing. Mixed linear models were used to compare the biomechanical outcomes between sexes and suture groups.

Results

When treated with absorbable suture, females had a lower ACL linear stiffness (females, 11 N/mm [range, 8–42]; males, 31 N/mm [range, 12–56]; difference, 20 N/mm [95% confidence interval {CI}, 4–36]; p = 0.032), ACL yield (females, 121 N [range, 56–316]; males, 224 N [range, 55–538]; difference, 103 N [95% CI, 6–200]; p = 0.078), and maximum load (females, 128 N [range, 63–332]; males, 241 N [range, 82–538]; difference, 114 N [95% CI, 15–212]; p = 0.052) than males after 15 weeks of healing. Female knees treated with absorbable suture had a lower linear stiffness (absorbable, 11 N/mm [range, 8–42]; nonabsorbable, 25 N/mm [range, 8–64]; difference, 14 [95% CI, 2–26] N; p = 0.054), ACL yield (absorbable, 121 N [range, 56–316]; nonabsorbable, 230 N [range, 149–573]; difference, 109 N [95% CI, 56–162]; p = 0.002), and maximum load (absorbable, 128 N [range, 63–332]; nonabsorbable, 235 N [range, 151–593]; difference, 107 N [95% CI, 51–163]; p = 0.002) along with greater AP knee laxity at 30° (absorbable, 9 mm [range, 5–12]; nonabsorbable, 7 mm [range, 2–13]; difference, 2 mm [95% CI, 1–4]; p = 0.034) than females treated with nonabsorbable suture. When repaired using nonabsorbable suture, the biomechanical outcomes were similar between female and male knees (p > 0.10).

Conclusions

Females had significantly worse biomechanical outcomes than males when the repairs were performed using absorbable sutures. However, the use of nonabsorbable sutures ameliorated these differences between males and females.

Clinical Relevance

The current findings highlight the critical role of sex on the biomechanical outcomes of bridge-enhanced ACL repair in a relevant large animal model. Better understanding of the mechanisms responsible for these observations using preclinical models and concomitant clinical studies in human patients may allow for additional development of sex-specific surgical and rehabilitative strategies with potentially improved outcomes in women.     

Addition of Vancomycin to Cefazolin Prophylaxis Is Associated With Acute Kidney Injury After Primary Joint Arthroplasty

Background

With increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in patients undergoing hip and knee arthroplasty, some have advocated a dual-antibiotic regimen including vancomycin as prophylaxis against surgical site infections. However, routine administration of vancomycin may result in impaired renal functions in susceptible patients.

Questions/purposes

The purpose of this study was to determine whether patients receiving antibiotic prophylaxis with cefazolin and vancomycin have a higher risk of postoperative acute kidney injury (AKI) compared with patients receiving cefazolin alone before elective primary hip and knee arthroplasty. We also aimed to compare severity and recovery of AKI in these two cohorts and to determine independent risk factors for AKI.

Methods

We retrospectively evaluated a series of 1828 patients undergoing primary hip and knee arthroplasty over a 2-year period who received either cefazolin (n = 500) or cefazolin and vancomycin (n = 1328) as perioperative antibiotic prophylaxis. During the study period, a perceived high prevalence of MRSA infections at our institution led some surgeons to add vancomycin to the prophylactic antibiotic regimen. The patient characteristics, case mix, and preoperative renal function and baseline creatinine clearance were similar between the two groups. We defined AKI according to the published Acute Kidney Injury Network (AKIN) criteria, and the risk of AKI in both groups was compared. We also compared the proportions of patients by AKIN severity stage and assessed recovery as defined by creatinine levels showing kidney function reaching 50% baseline. The American Society of Anesthesiologists (ASA) classification, preoperative chronic kidney disease, intraoperative fluid requirements, and estimated blood loss were recorded. We analyzed the data using a multivariate logistic regression model to identify potential independent risk factors, including dual antibiotic therapy.

Results

Patients receiving dual antibiotics were more likely to develop AKI compared with those receiving cefazolin alone (13% versus 8%, p = 0.002). Dual-antibiotic prophylaxis also was associated with greater severity; patients in the dual antibiotic group had higher rates of Grade II and III acute kidney injury (3% versus 0%, p = 0.003). There was no difference in the rate of return to baseline renal function (2 ± 1.4 days versus 3 ± 3.4 days; mean difference, 0.5 days; 95% confidence interval [CI], −0.2 to 1.2 days; p = 0.155). Controlling for confounding variables, dual antibiotic prophylaxis (adjusted odds ratio [OR], 1.82; 95% CI, 1.25–2.64; p = 0.002), ASA class (adjusted OR, 1.64; 95% CI, 1.24–2.17; p = 0.001), and preoperative kidney disease (adjusted OR, 1.81; 95% CI, 1.30–2.52; p = 0.001) were independent risk factors for AKI after primary total joint arthroplasty.

Conclusions

Without a clear advantage in reducing surgical site infections, the utility and safety of routine addition of vancomycin to the prophylactic regimen in all patients undergoing primary hip and knee arthroplasty should be avoided. Further prospective studies should look at the efficacy of preoperative MRSA screening, decolonization, and selective use of vancomycin in high-risk patients.

Level of Evidence

Level III, therapeutic study.     

Incidence and Risk Factors of Allograft Bone Failure After Calcaneal Lengthening

Background

Calcaneal lengthening with allograft is frequently used for the treatment of patients with symptomatic planovalgus deformity; however, the behavior of allograft bone after calcaneal lengthening and the risk factors for graft failure are not well documented.

Questions/purposes

(1) What proportion of the patients treated with allograft bone had radiographic evidence of graft failure and what further procedures were performed? (2) What are the risk factors for radiographic graft failure after calcaneal lengthening? (3) What patient factors are associated with the magnitude of correction achieved after calcaneal lengthening?

Methods

Between May 2003 and January 2014, we performed 341 calcaneal lengthenings on 202 patients for planovalgus deformity, the etiology of which included idiopathic, cerebral palsy, and other neuromuscular disease. Of these, 176 patients (87%) had adequate followup for graft evaluation, defined as lateral radiographs taken before and at least 6 months after the index procedure (mean, 18 months; range, 6–100 months) and 117 patients (58%) had adequate followup for the assessment of the extent of correction, defined as weightbearing anteroposterior and lateral radiographs taken before and at least 1 year after the index procedure (mean, 24 months; range, 12–96 months). These patients’ results were evaluated retrospectively. The Goldberg scoring system was chosen for demonstration of allograft behavior. A score lower than 6 at 6 months after surgery was defined as radiographic graft failure; the highest possible score was 7 points, and this represented graft incorporation with excellent reorganization of the graft and no loss of height. The patient age, sex, diagnosis, graft material, ambulatory status, and use of antiseizure medication were evaluated as possible risk factors, and we controlled for the interaction of potentially confounding variables using multivariate analysis. Additionally, six radiographic indices were analyzed for their effects on the extent of correction.

Results

The mean estimated Goldberg score was 6 (SD, 1.14) at 6 months after calcaneal lengthening with 11 feet (4%) classified as radiographic graft failure (Goldberg score < 6). Of these, four feet (1%) underwent reoperation using an iliac autograft bone resulting from pain and loss of correction. Multivariate analysis showed that the tricortical iliac crest allograft was superior to the patellar allograft (odds ratio [OR], 3.2; 95% confidence interval [CI], 1.1–9.8; p = 0.038) and the possibility of radiographic graft failure was found to increase along with age (OR, 1.2; 95% CI, 1.0–1.3; p = 0.006). Radiographically, the extent of correction was found to decrease with patient age, as observed at the anteroposterior talus-first metatarsal angle (p < 0.001), lateral talocalcaneal angle (p < 0.001), lateral talus-first metatarsal angle (p < 0.001), and relative calcaneal length (p = 0.041).

Conclusions

Graft failure can occur after calcaneal lengthening using allograft. Our study showed that the tricortical iliac allograft was superior to the patellar allograft, and further studies are warranted to further elucidate the effects of age on radiographic graft failure.

Level of Evidence

Level III, therapeutic study.     

What Risk Factors Predict Recurrence of Heterotopic Ossification After Excision in Combat-related Amputations?

Background

Heterotopic ossification (HO) is common after combat-related amputations and surgical excision remains the only definitive treatment for persistently symptomatic HO. There is no consensus in the literature regarding the timing of surgery, and recurrence frequency, reexcision, and complications have not been reported in large numbers of patients.

Questions/purposes

(1) What are the rates of symptomatic recurrence resulting in reexcision and other complications resulting in reoperation in patients with HO? (2) Is either radiographic or symptomatic recurrence dependent on timing and type of initial surgery, the experience of the surgeon in performing the procedure, the severity of preexcision HO, the presence of concomitant neurologic injury, or the use of postoperative HO prophylaxis?

Methods

Between March 2005 and March 2013 our institution treated 994 patients with 1377 combat-related major extremity amputations; of those, 172 amputations underwent subsequent excision of symptomatic HO. The mechanism of injury resulting in nearly all amputations (n = 168) was blast-related trauma. We reviewed medical records and radiographs to collect initial grade of HO, radiographic recurrence, complete compared with partial excision, concomitant neurologic injury, timing to initial surgery, surgeon experience, and use of postexcision prophylaxis with our primary study outcome being a return to the operating room (OR) for repeat excision of symptomatic HO. All 172 combat-related amputations were considered for this study irrespective of followup, which was noted to be robust, with 157 (91%) amputations having at least 6 months clinical followup by an orthopaedic surgeon or physiatrist (median, 20 months; range, 0–88 months).

Results

Eleven of 172 patients (6.5%) underwent reexcision of HO, and 67 complications resulting in return to the OR occurred in 53 patients (31%) of patients. Multivariate analysis of our primary outcome measure showed more frequent symptomatic recurrences requiring reexcision when initial excision was performed as a partial excision (p = 0.03; odds ratio [OR], 5.0; 95% confidence interval [CI], 1.2–29.6) or when the initial excision was performed within 180 days of injury (p = 0.047; OR, 4.1; 95% CI, 1.02–16.6). There was no association between symptomatic recurrence and HO grade, central nervous system injury, experience of the attending surgeon, or postoperative prophylaxis. Radiographic recurrence was observed when partial excisions (eight of 30 [27%]) were done compared with complete excisions (five of 77 [7%]; p = 0.008).

Conclusions

HO is common after combat-related amputations, and patients undergoing surgical excision of HO for this indication often have complications that result in repeat surgical procedures. Partial excisions of immature lesions more often resulted in both symptomatic and radiographic recurrence. The likelihood of a patient undergoing reexcision can be minimized by performing a complete excision at least 180 days from injury to surgery with no evidence of a reduced risk of reexcision by waiting longer than 270 days.

Level of Evidence

Level III, therapeutic study.