Risk Factors for Periprosthetic Femoral Fracture in Non-cemented Total Hip Arthroplasty Through the Direct Anterior Approach.

Background: Although total hip arthroplasty (THA) performed through the direct anterior (DA) approach is frequently marketed as superior to other approaches, there are concerns about increased risks of intraoperative and early postoperative femoral fracture. Purpose: We sought to assess patient-specific and radiographic risk factors for intraoperative and early postoperative (90-day) periprosthetic femoral fracture (PPFx) following DA approach THA. Methods: We retrospectively reviewed 1107 consecutive, primary, non-cemented DA THAs, performed between April 2009 and January 2015, for intraoperative and early postoperative PPFx. Patients lost to follow-up before 90 days (63), cemented or hybrid THA (52), or early femoral failure for another indication (3) were excluded, yielding 989 hips for analysis. Demographic variables and patient comorbidities were analyzed as risk factors for PPFx. Continuous variables were initially compared with 1-way analysis of variance (ANOVA) and categorical variables with chi-square test. A demographic matched-paired radiographic analysis was performed for femoral stem canal fill and compared using univariate logistic regression. Results: The incidence of perioperative PPFx was 2.02%, including 10 intraoperative and 10 early postoperative fractures. Sustaining a postoperative PPFx was associated with being 70 years old or older with a body mass index (BMI) of less than 25, or with having either osteoporosis or Parkinson disease. Radiographs demonstrated that intraoperative PPFx was associated with stems that filled greater proximally rather than distally. Conclusion: Our cohort study found older age, age over 70 with BMI of less than 25, osteoporosis, and Parkinson disease were associated with increased risk for early postoperative PPFx following DA approach THA. Intraoperative fractures may occur with disproportionate proximal femoral canal fill. Further study can evaluate whether cemented femoral components may mitigate risk in these patient populations.

Iliopsoas Impingement After Direct Anterior Approach Total Hip Arthroplasty: Epidemiology, Risk Factors, and Treatment Options.

BACKGROUND: The objective of this study is to evaluate the incidence, natural history, response to treatment, and risk factors for anterior iliopsoas impingement (AIPI) after direct anterior approach (DAA) total hip arthroplasty (THA). METHODS: Between January 1, 2009 and January 4, 2014, 600 patients (655 hips) who underwent primary DAA THA were retrospectively reviewed. AIPI incidence was calculated. Natural history and response to a stepwise treatment approach was assessed. Radiographic anterior acetabular component overhang was measured. Asymptomatic controls were used to identify risk factors for the development of AIPI. RESULTS: In total, 518 patients (559 hips) met the inclusion criteria. The incidence of AIPI was 32/559 (5.7%). Symptom resolution occurred in 22/32 (68.8%) patients at final follow-up. Nonoperative management was successful in 15/32 (46.9%) patients. Operative intervention resulted in symptom resolution in 5/8 (62.5%) patients. On univariate analysis, female gender (odds ratio [OR] 2.79), acetabular component to native femoral head diameter ratio above 1.1 (OR 3.85), and any measurable overhang (OR 7.07) significantly raised the risk of AIPI, while increasing native femoral head diameter was protective for AIPI (OR 0.83). CONCLUSION: AIPI is a cause of groin pain after DAA THA, which often improves with conservative measures. Significant predisposing factors for AIPI include female gender, small native femoral head diameter, increased acetabular component to femoral head diameter ratio, and most notably, any measurable acetabular component overhang. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Brachial Plexus Birth Injury in the Preterm Infant: Suspecting the Unsuspected.

BACKGROUND: Prematurity is usually considered as a protective factor for brachial plexus birth injury (BPBI). However, BPBI can occur in the preterm infant, and can cause significant dysfunction and morbidity. There is scant literature regarding this subgroup of patients with BPBI. METHODS: Patients were identified through a retrospective search of a prospective BPBI registry at a single tertiary pediatric referral center. Prematurity was defined as birth at or before gestational age of 36 (6/7) weeks. Thirty-six arms in 34 patients were included in this study. Data were obtained from patient charts documenting standardized brachial plexus clinical examinations at each visit, medical imaging, questionnaires for parents, and outside perinatal records brought in by parents. RESULTS: The youngest infant identified with BPBI was born at 23 weeks' gestation. Median birth weight was 3005 g (range: 580 to 4600 g). Twenty-nine arms in 28 patients were categorized into the "late preterm group" [34 to 36 (6/7) weeks gestation], and 7 arms in 6 patients were categorized into the "early preterm group" (<34 wk). Four of 6 (67%) subjects in the early preterm group were delivered vaginally in the breech position, compared with 4 of 28 subjects (14%) in the late preterm group (P=0.02). All 3 twin gestation infants with BPBI were the younger twin and born vaginally in the breech position. Delayed diagnosis (>7 d) occurred in 11 arms in 10 subjects (31%). Median delay in diagnosis was 73 days (range: 10 to 1340 d). Spontaneous recovery of antigravity elbow flexion occurred in 65% of arms (at median 5 mo, range: 1 to 17 mo). Overall, 89% (32/36) of arms with BPBI had residual neurological deficit and 53% (19/36) of arms underwent at least 1 surgical intervention at latest follow-up (median age at latest follow-up: 60 mo, range: 1 to 237 mo). CONCLUSIONS: BPBI in preterm infants is rare but does occur and can cause significant morbidity. Delayed diagnosis of BPBI is common in preterm infants. A high index of suspicion should be maintained to avoid delayed diagnosis that may jeopardize treatment options. Preterm infants may be more susceptible to birth trauma from breech deliveries and shoulder dystocia, as evidenced by far higher incidence of these factors compared with term infants with BPBI in literature. LEVEL OF EVIDENCE: Level IV-case series.

The Effect of Femoral Cutting Jig Design on Restoration of Femoral Offset in Posterior-Referenced Total Knee Arthroplasty.

Femoral component sizing and rotation in total knee arthroplasty (TKA) affects patellofemoral tracking and tibiofemoral mechanics. Posterior referencing is said to optimize restoration of posterior condylar offset. However, it typically allows the surgeon to select 3° to 5° of external rotation to the posterior condylar axis, inevitably changing the offset of one or both condyles. The axis about which external rotation occurs varies between the jigs of various TKA systems. The location of this axis can result in a medial, central, or lateral reference point for posterior offset restoration. Variations in jig design will result in varying posterior offset changes at the same jig setting, with differential effects on balance between the flexion and extension gaps. Using identical Sawbones in a controlled laboratory setting, 9 TKA instrumentation systems were examined. Two systems referenced medially, 1 referenced laterally, and 6 referenced centrally. The authors measured distal and posterior resections in both 3° and 5° of external rotation to the posterior condylar axis. They calculated changes in both distal and posterior joint lines using resection measurements and implant specifications. Posterior resection thicknesses were greatest with instruments that referenced laterally and least with instruments that referenced medially. With increasing external rotation, instruments that referenced off the lateral femoral condyle introduced the greatest mismatch between the distal and posterior joint lines, as compared with instruments that referenced centrally or medially. Surgeons should be aware that laterally referencing systems can differentially restore distal and posterior joint lines at higher settings of femoral external rotation, potentially introducing incongruity between flexion and extension gaps if the posterior slope of the tibia is maintained. This may be particularly problematic if flexion laxity is increased by posterior cruciate ligament sacrifice. [Orthopedics. 2019; 42(6):316-322.].

Closed incision negative pressure therapy decreases complications after periprosthetic fracture surgery around the hip and knee.

INTRODUCTION: Periprosthetic fractures (PPFXs) are becoming increasingly common following total hip arthroplasty (THA) and total knee arthroplasty (TKA). Patients sustaining PPFXs face considerable perioperative morbidity, with relatively increased rates of surgical site infection. We sought to evaluate the efficacy of closed-incision negative-pressure wound therapy (ciNPT) in decreasing perioperative wound complications following lower extremity periprosthetic fracture surgery. METHODS: We performed a retrospective review of 69 consecutive patients who underwent surgery to address lower extremity periprosthetic fractures around hip or knee implants performed over a 6.5-year period. The population was divided into two groups based on the surgical dressing used at the conclusion of the procedure: (1) a sterile, antimicrobial hydrofiber dressing, or (2) ciNPT. There were no baseline demographic differences between the two groups. Rates of wound complications, surgical site infection, and reoperation related to the surgical site were compared between groups. Continuous variables were analyzed using a student's t-test, and categorical variables using either chi-square or fisher's exact test. RESULTS: Patients treated with ciNPT developed fewer wound complications (4% vs. 35%; p=0.002), fewer deep infections (0% vs. 25%; p=0.004), and underwent fewer reoperations related to the surgical site (4% vs. 25%; p=0.021) compared to patients treated with standard of care. CONCLUSIONS: Our findings suggest that ciNPT may reduce wound complications, SSIs, and reoperations in patients undergoing lower extremity periprosthetic fracture surgery. This is the first study to investigate ciNPT as a treatment for periprosthetic fracture surgery, and has the potential to change the postoperative management of these patients.

Revision Arthroplasty for the Management of Stiffness After Primary TKA.

BACKGROUND: The aim of this study was to evaluate the results of revision surgery for the treatment of stiffness after total knee arthroplasty (TKA). METHODS: An IRB-approved retrospective review was performed to identify patients who were revised due to stiffness after a primary TKA. Patients were included when at least one major component had to be revised due to stiffness after primary TKA with a minimum follow-up of 2 years. Patients with history of previous infection and those treated with isolated polyethylene exchange were excluded. RESULTS: The study group involved 42 knees. Mean follow-up was 47 months (24-109 months). Mean flexion contracture improved from 9.7° (0°-35°) preoperatively to 2.3° (0°-20°) postoperatively (P < .00). Mean flexion improved from 81.5° (10°-125°) preoperatively to 94.3° (15°-140°) postoperatively (P .02). Mean range of motion improved from 72.0° preoperatively (10°-100°) to 92° (15°-140°) postoperatively (P < .00). Mean Knee Society knee scores improved from 43.9 points (15-67) preoperatively to 72.0 points (50-93) at latest follow-up and mean Knee Society Function scores improved from 48.7 (35-80) preoperatively to 70.1 points (30-90) postoperatively. Pain improved in 73% of the patients. CONCLUSION: Revision surgery appears to be a reasonable option for patients presenting with pain and stiffness after TKA. However, the benefits may be modest as the outcomes still do not approach those achieved with primary TKA.

Adoption of Robotic vs Fluoroscopic Guidance in Total Hip Arthroplasty: Is Acetabular Positioning Improved in the Learning Curve?

BACKGROUND: Acetabulum positioning affects dislocation rates, component impingement, bearing surface wear rates, and need for revision surgery. Novel techniques purport to improve the accuracy and precision of acetabular component position, but may have a significant learning curve. Our aim was to assess whether adopting robotic or fluoroscopic techniques improve acetabulum positioning compared to manual total hip arthroplasty (THA) during the learning curve. METHODS: Three types of THAs were compared in this retrospective cohort: (1) the first 100 fluoroscopically guided direct anterior THAs (fluoroscopic anterior [FA]) done by a surgeon learning the anterior approach, (2) the first 100 robotic-assisted posterior THAs done by a surgeon learning robotic-assisted surgery (robotic posterior [RP]), and (3) the last 100 manual posterior (MP) THAs done by each surgeon (200 THAs) before adoption of novel techniques. Component position was measured on plain radiographs. Radiographic measurements were taken by 2 blinded observers. The percentage of hips within the surgeons' "target zone" (inclination, 30°-50°; anteversion, 10°-30°) was calculated, along with the percentage within the "safe zone" of Lewinnek (inclination, 30°-50°; anteversion, 5°-25°) and Callanan (inclination, 30°-45°; anteversion, 5°-25°). Relative risk (RR) and absolute risk reduction (ARR) were calculated. Variances (square of the standard deviations) were used to describe the variability of cup position. RESULTS: Seventy-six percentage of MP THAs were within the surgeons' target zone compared with 84% of FA THAs and 97% of RP THAs. This difference was statistically significant, associated with a RR reduction of 87% (RR, 0.13 [0.04-0.40]; P < .01; ARR, 21%; number needed to treat, 5) for RP compared to MP THAs. Compared to FA THAs, RP THAs were associated with a RR reduction of 81% (RR, 0.19 [0.06-0.62]; P < .01; ARR, 13%; number needed to treat, 8). Variances were lower for acetabulum inclination and anteversion in RP THAs (14.0 and 19.5) as compared to the MP (37.5 and 56.3) and FA (24.5 and 54.6) groups. These differences were statistically significant (P < .01). CONCLUSION: Adoption of robotic techniques delivers significant and immediate improvement in the precision of acetabular component positioning during the learning curve. While fluoroscopy has been shown to be beneficial with experience, a learning curve exists before precision improves significantly.

Differential Effect of Total Knee Arthroplasty on Valgus and Varus Knee Biomechanics During Gait.

BACKGROUND: Total knee arthroplasty and its relation to gait abduction or adduction moment has not been fully described. METHODS: Gait analysis was performed on 25 patients (27 knees) preoperatively, 6 months and 1 year after total knee arthroplasty. Reflective markers were placed on the lower extremity, and motion data were collected at 60 Hz using 6 infrared cameras. Ground reaction forces were recorded at 960 Hz with a force plate. Stance phase was divided into braking and propulsive phases. Coronal knee angles and moments were calculated. Repeated-measures analysis of variance was used to compare frontal plane knee impulse over time and between the braking and propulsive phases of stance. RESULTS: In varus knees, static alignment was corrected from 2.2° varus to 3.3° valgus and in valgus knees from 15.2° valgus to 2.7° valgus (P < .010). Braking phase adduction impulse decreased from 0.145 to 0.111 at 6 months but increased to 0.126 Nm/kg s (P > .05) at 1 year. Propulsive phase impulse changed from 0.129 to 0.085 and persisted at 1 year. Impulse changed from 0.01 (abduction) to 0.11 Nm/kg s (adduction) at 6 months and persisted (P = .01). CONCLUSION: Restoration of anatomic alignment and soft tissue balancing changes the lateral loading conditions of valgus knees. Both cases, between 6 months and 1 year, increased peak moment.

Risk Factors for Wound Complications After Direct Anterior Approach Hip Arthroplasty.

BACKGROUND: Previous studies have suggested that wound complications may be higher after direct anterior approach (DAA) hip arthroplasty, but, specific risk factors have not been closely examined. METHODS: We conducted a retrospective case-control study of 651 consecutive DAA hip arthroplasty surgeries performed by 2 surgeons over a 3-year period. Outcome measures included any postoperative wound problem (including prolonged drainage, wound dehiscence, wound necrosis, suture granuloma, and superficial infection) requiring additional intervention or reoperation. Univariate odds ratios (ORs) were calculated, and multivariate logistic regression analysis was performed to determine risk correlation. Receiver operator characteristic (ROC) curves were created to determine disease predictability. RESULTS: A total of 75 patients (11.5%) experienced wound complications requiring additional intervention, of which, 13 (1.9%) required reoperation. Multivariate regression analysis found that development of wound complications was significantly and independently associated with body mass index (BMI) 30-35 kg/m2 (OR 2.05; 95% confidence interval [CI] 1.08-3.88), BMI 35-40 kg/m2 (OR 3.40; 95% CI 1.42-8.26), BMI > 40 kg/m2 (OR 7.28; 95% CI 2.55-20.78), and diabetes mellitus (OR 2.97; 95% CI 1.46-6.07). Reoperation for wound complication was significantly associated with BMI > 40 kg/m2 (OR 5.68; 95% CI 1.17-27.48) and diabetes mellitus (OR 13.08; 95% CI 3.97-43.11). Optimal cutoff values for BMI were found through receiver operator characteristic curve analysis to be 28.0 kg/m2 for development of wound complications and 28.2 kg/m2 for reoperation for wound complications. CONCLUSION: Obesity and diabetes mellitus are significantly associated with postoperative wound-healing complications and the need for reoperation for these wound complications after DAA hip arthroplasty.

Closed-Incision Negative-Pressure Therapy Versus Antimicrobial Dressings After Revision Hip and Knee Surgery: A Comparative Study.

BACKGROUND: This study evaluates the efficacy of closed-incision negative-pressure therapy (ciNPT) in decreasing wound complications and surgical site infections (SSIs) after revision hip and knee surgery. METHODS: A retrospective quality improvement analysis of 138 consecutive revision hip and knee operations performed by a single surgeon over a 34-month period was performed. ciNPT was used selectively in higher-risk patients with multiple risk factors for SSIs over the last 15 months of the study period. Rates of wound complications, SSIs, and reoperation were compared with patients treated with a sterile antimicrobial dressing. RESULTS: Antimicrobial dressings were used in 108 patients, whereas ciNPT was used in 30 patients. Patients treated with ciNPT developed fewer overall wound complications (6.7% vs 26.9%, P = .024) and fewer total SSIs (3.3% vs 18.5%, P = .045) than patients treated with antimicrobial dressings. In addition, there were trends toward a lower rate of superficial wound dehiscence (6.7% vs 19.4%, P = .163), fewer deep periprosthetic joint infections (0.0% vs 9.3%, P = .118), and fewer reoperations (3.3% vs 13.0%, P = .191) among patients treated with ciNPT. CONCLUSION: Our findings suggest that ciNPT may decrease wound complications and SSIs in patients undergoing revision hip and knee surgery.