Femoral Morphology in Patients Undergoing Periacetabular Osteotomy for Classic or Borderline Acetabular Dysplasia: Are Cam Deformities Common?

BACKGROUND: The primary purpose of our study was to determine the prevalence of Cam deformity in patients with symptomatic acetabular dysplasia (SAD) who underwent periacetabular osteotomy (PAO). METHODS: We retrospectively reviewed 164 SAD PAO patients from 2 institutions. Preoperative anteroposterior and frog-lateral radiographs were analyzed for lateral center edge angle (LCEA), retroversion, alpha angles, and anterior femoral head-neck offset. Hips were classified as dysplastic (LCEA <20°, group A, n = 142) and borderline dysplastic (LCEA 20°-25°, group B, n = 22). There were 128 females and 36 males with an average age of 29 years (range 13-56). RESULTS: The overall prevalence of Cam deformity was 10% (17 of 164) in SAD patients. There was no difference in the prevalence of Cam deformity between the groups (P > .99). CONCLUSION: Prevalence of Cam deformities in our series of SAD patients having undergone PAO is less than prior reports. Careful radiographic measurement should be performed to avoid overtreating these hips with unnecessary osteochondroplasty procedures.

Medial sided articular impaction in tibial plateau fractures.

INTRODUCTION: Tibial plateau fractures are a heterogenous group of injuries with a variable amount of articular injury and are commonly associated with lateral sided articular impaction. Previous work has focused on describing the morphology of tibial plateau fractures, but has neglected description of medial sided articular impaction. The aim of this investigation was to assess the morphology of medial sided articular impaction in tibial plateau fractures, with specific attention directed toward the frequency, location, size, and associated fracture patterns. METHODS: Skeletally mature patients presenting to a Level I trauma center from 2008-2018 with a tibial plateau fracture (AO/OTA 41B-C) were identified retrospectively. Fractures were classified by AO/OTA and Schatzker type. Radiographs and computed tomography (CT) scans were reviewed to identify and localize medial sided articular impaction. The location and surface area of impaction was characterized by creating frequency diagram heat maps from axial CT scans. Descriptive statistics were performed using standard measures. RESULTS: Of the 1032 tibial plateau fractures included, 82 (7.9%) were noted to have medial sided articular impaction. Rate of impaction varied by fracture type (p = 0.03): Schatzker II, 2% (7 of 381); Schatzker IV, 21% (19 of 96); and Schatzker VI, 11% (56 of 524). Average total surface area of impaction was 9% of the total and 19% of the medial plateau area. Area of impaction varied by fracture type (p = 0.004): Schatzker II, 6% (95% confidence interval [CI], 4%-7%); Schatzker IV, 11% (95% CI, 9%-13%), and Schatzker VI, 9% (95% CI, 7%-11%). The area of impaction occurred primarily along the lateral aspect of the medial plateau in Schatzker II fractures, in the anteromedial quadrant of Schatzker IV fractures, and was evenly distributed across the medial plateau in Schatzker VI fractures. CONCLUSIONS: Surgeons should be aware that medial articular impaction is present in approximately 8% of tibial plateau fractures. Schatzker IV fractures are most likely to have medial impaction and a larger proportion of the joint surface involved in these injuries.

Analysis of Computed Tomography-Based Technique for Measuring Femoral Anteversion: Implications for Measuring Rotation After Femoral Intramedullary Nail Insertion.

OBJECTIVES: To assess the reliability of the current computed tomography (CT)-based technique for determining femoral anteversion and quantify the prevalence and magnitude of side-to-side differences. DESIGN: Cross-sectional cohort study. SETTING: Academic trauma center. PATIENTS: We reviewed CT scans from 120 patients with bilateral full-length axial cuts of both femurs. Two hundred forty femurs with no fractures or other identifying features in their femora were included. Ten unique data sets were created to measure anteversion of the left and right sides. MAIN OUTCOME MEASUREMENTS: Intraobserver and interobserver reliability were calculated using intraclass correlation coefficients (ICCs) and pooled absolute differences. The mean absolute difference between the sides was determined using a fixed-effects model. RESULTS: Interobserver reliability was high (ICC: 0.85, 95% confidence interval [CI]: 0.83-0.88). The pooled mean absolute magnitude of variation between reviewers was small at 1.6 degrees (95% CI: 1.4-1.8 degrees) per scan. The intraobserver reproducibility was high (ICC: 0.91, 95% CI: 0.88-0.93) with a mean error of 2.7 degrees (95% CI: 2.2-3.1 degrees) per repeat viewing of the same scan by the same person. The magnitude of side-to-side variation was 2.0 degrees (95% CI: 1.5-2.6 degrees). Twenty-one subjects (18%, 95% CI: 12%-25%) had a mean side-to-side calculated femoral anteversion difference of ≥10 degrees, whereas 6 (5%, 95% CI: 2-10) subjects had a calculated mean side-to-side difference of ≥15 degrees. CONCLUSIONS: CT based femoral anteversion measurement techniques demonstrate good precision. Only 1 in 20 patients had side-to-side differences of 15 degrees or more.

Measuring Lateral Screw Protuberance Is a Clinically Accurate Method for Quantifying Femoral Neck Shortening.

OBJECTIVES: The purpose of this study is to compare the reliability and accuracy of the screw protuberance method (SPM) and overlay method (OM) for measuring femoral neck shortening on anterior-posterior (AP) radiographs. The secondary aim is to investigate the changes in reliability and accuracy with varying femoral rotation. METHODS: Radio-opaque femur sawbone models were fitted with either 3 cancellous screws or a sliding hip screw implant. Anterior-posterior radiographs were obtained using C-arm fluoroscopy with femoral neck shortening up to 15 mm and with the femoral shaft in 30 degrees of internal rotation to 30 degrees of external rotation (ER). Four observers measured femoral neck shortening at 2 time points. Intraobserver and interobserver reliability were calculated using the intraclass coefficient. Accuracy was analyzed through a Bland-Altman agreement statistic stratified by femoral rotation. RESULTS: Both measurement techniques displayed excellent reliability, regardless of femoral rotation or implant. There was a significant difference in femoral neck shortening measurements with rotation for both the OM (P < 0.001) and SPM (P < 0.001). Both methods are accurate within 1 mm of the actual magnitude of shortening from 30-degree internal rotation to 15-degree ER. At 30-degree ER, shortening was underestimated by -2.10 mm using the OM (95% confidence interval, -2.43 to -1.76; P < 0.01) and by -1.64 mm using the SPM (95% confidence interval, -1.83 to -1.45; P < 0.01). CONCLUSION: This study demonstrates that both the OM and SPM are accurate and reliable assessments for femoral neck shortening; however, both methods are sensitive to extreme ER. Given the simplicity of the SPM technique, it may have increased utility for pragmatic research studies.

Posterolateral plating is a safe alternative for the treatment of distal tibial fractures.

INTRODUCTION: We assessed the outcome and safety of posterior plating of distal tibial fractures. METHODS: We conducted a retrospective case series at a Level I trauma center. Seventy-four consecutive patients with distal tibial fractures treated with anatomically contoured 3.5-mm T-shaped locking compression plate using a posterolateral approach from January 2008 through April 2018 were included in the study. The mean patient age was 48 years (range, 18-87 years). Fifty-nine percent of the patients were male patients, 47% of the fractures were open fractures; and 27% of the patients had multiple traumatic injuries. Eleven fractures were AO/OTA type 42, 22 were type 43A, and 41 were type 43C. Sixty-two (84%) patients were treated with initial spanning external fixation (median time, 23 days) and staged open reduction and internal fixation. The main outcome measure was unplanned reoperation to address implant failure, nonunion, deep surgical site infection, or symptomatic implant. RESULTS: Overall risk of unplanned reoperation was 15% (11 of 74 patients, 95% confidence interval, 9%-25%). Four (5%) reoperations were for nonunion, three (4%) were for surgical site infection, two (3%) were for infected nonunion, and two (3%) were for implant prominence. Loss of alignment >10 degrees occurred in one patient who underwent unplanned reoperation for nonunion. No plate breakage occurred. Median time to reoperation was 221 days (range, 22-436 days). Only one other complication was noted: wound dehiscence associated with the posterolateral approach, which was treated with irrigation and débridement and a 6-week regimen of oral antibiotics. CONCLUSIONS: Use of a posterolateral approach with a pre-contoured locking compression T-plate for the treatment of distal tibial fractures led to reasonable outcomes with an acceptable risk of unplanned reoperation, even with a high proportion of open fractures commonly staged with external fixation.

Two-Stage Revision of Total Hip Arthroplasty for Infection Is Associated with a High Rate of Dislocation.

BACKGROUND: Two-stage exchange is the most common form of treatment of chronic infection following total hip arthroplasty (THA). We examined the prevalence of, and risk factors associated with, hip instability following 2-stage exchange as well as the fate of reimplanted hip prostheses that dislocated. METHODS: Data on 515 2-stage exchange THAs performed between 2000 and 2014 at a single institution were retrospectively reviewed. Risk factors for instability as well as postoperative reoperations and revisions were analyzed. The impact of dislocation on these outcomes was evaluated as well. The mean age at the time of reimplantation was 65 years, and the mean duration of follow-up was 5 years (range, 2 to 15 years). RESULTS: Dislocation occurred in 52 hips following reimplantation (cumulative probability = 8.9% at 1 year). There was a higher risk of instability in women (hazard ratio [HR] = 1.8, p = 0.038) and in those who had a history of dislocation prior to the 2-stage revision (HR = 5.1, p < 0.001). Younger age, body mass index, number of previous operations, spacer type, surgical approach, use of a constrained liner, femoral head diameter, and persistent or recurrent infection were not found to be significant risk factors. Patients with an absent or ununited greater trochanter or abductor deficiency also had a higher rate of dislocation (HR = 30, p < 0.001), as did patients who underwent reimplantation with a megaprosthesis (HR = 6.0, p < 0.001). The risk of additional reoperations (HR = 121, p < 0.001) and revision surgery (HR = 13, p < 0.001) was significantly higher in patients who experienced a dislocation after the 2-stage exchange. CONCLUSIONS: Dislocation after 2-stage exchange THA continues to be a major concern, with the 1-year cumulative probability found to be 9% in the present study. Female sex, a history of dislocation, an absent or ununited greater trochanter or abductor deficiency, and reimplantation with a megaprosthesis were identified as risk factors for dislocation. There is a remarkable 121-fold increase in the rate of reoperations and a 13-fold increase in the rate of revisions in hips that dislocated after 2-stage exchange THA. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Elevated Serum Titanium Level as a Marker for Failure in a Titanium Modular Fluted Tapered Stem.

Serum ion concentrations of cobalt and chromium are commonly used to monitor for the development of local metal reactions in metal-on-metal total hip arthroplasties, as well as dual-modular constructs. Although rarely used in clinical practice, elevated serum titanium levels have the ability to indicate a failure with contemporary revision constructs, such as with titanium modular fluted tapered (TMFT) stems. The authors report the case of a 64-year-old man with a TMFT stem after revision total hip arthroplasty for a dual-modular neck construct who had set screw disengagement with subsequent proximal body loosening. The patient's serum cobalt and chromium levels were normal, but he had a markedly elevated serum titanium level, indicating failure of the titanium modular junction. Implant failures at modular junctions in femoral components are well described. Although several different failure mechanisms have been defined, to the authors' knowledge this is the first reported failure of this particular TMFT stem. In addition, this is the first report describing the use of serum titanium levels in identifying a novel failure mechanism. With the popularity of this stem, surgeons should be aware that an elevated serum titanium level may aid in the diagnosis of this unique complication. [Orthopedics. 2016; 39(4):e768-e770.].