Douglas S. Weinberg

Pelvic Incidence and Acetabular Version in Slipped Capital Femoral Epiphysis.

Background: The etiology of slipped capital femoral epiphysis (SCFE) is multifactorial, but the role of sagittal balance of the pelvis as a contributing factor to its development has not been well studied. Our primary purpose was to determine whether a smaller pelvic incidence (PI), a position-independent anatomic parameter that regulates pelvic orientation, could be a factor that increases shear stress in the epiphyseal growth plate and potentially contributes to the development of SCFE. We also set out to determine whether acetabular retroversion was associated with SCFE. Methods: We obtained 14 cadaveric pelvi from the Hamann-Todd Osteological Collection whose femurs showed evidence of post-SCFE deformity. Two hundred age-matched, sex-matched, and race-matched pelvi were used as controls. PI and acetabular version were measured using standardized lateral photographs and goniometers, respectively. T tests were performed to evaluate for differences in measured parameters between groups. Results: The mean PI was 40.6±6.1 degrees for SCFE specimens and 47.4±9.9 degrees for normal specimens (P=0.01). The mean version of SCFE and normal acetabula was 15±7 and 17±6 degrees, respectively (P=0.39). There was also no significant difference in version between SCFE acetabula and the contralateral, uninvolved acetabular of the same specimen (15±7 vs. 17±8 degrees, P=0.33). Conclusions: Specimens with SCFE deformity demonstrated a smaller PI than a large cohort of normal control specimens. We found no significant difference between acetabular version of specimens with and without SCFE deformity. Contralateral or unaffected acetabuli of SCFE specimens were not more retroverted than the affected side of the same specimen. Clinical Relevance: Sagittal balance of the pelvis, and particularly decreased PI, may play an important role in the development of SCFE. The influence of mechanical factors beyond the hip joint in the development of SCFE should be considered by clinicians.

The Association of Tibia Femur Ratio and Degenerative Disease of the Spine, Hips, and Knees

Background: When individuals with asymmetric lower extremities present for evaluation of limb-length inequality, correction can occur at the tibia, femur, or in both bones; however, there are limited data available to justify either technique. The aim of this study is to examine the normal ratio of tibia length/femur length (T/F), and to explore the relationship between T/F ratio and osteoarthritis of the spine, hips, and knees. Methods: Bone lengths of 1152 cadaveric femora and tibiae from the Hamann-Todd osteological collection were measured. Degenerative joint disease was graded in the hip, knee, and spine. Correlations between the ratio of T/F and osteoarthritis were evaluated with multiple regression analysis. Results: The average ratio of T/F was 0.80±0.03. There was a strong correlation between age and arthritis at all sites, with standardized &bgr; ranging from 0.44 to 0.57 (P<0.0005 for all). There was a significant correlation between increasing T/F and hip arthritis (standardized &bgr;=0.08, P=0.006), and knee arthritis (standardized &bgr;=0.08, P=0.008). Discussion: Increasing tibia length relative to femur length was found to be a significant predictor of ipsilateral hip and knee arthritis. Therefore, we recommend that when performing limb lengthening, surgical planning should lean toward recreating the normal ratio of 0.80. In circumstances where one bone is to be overlengthened relative to the other, bias should be toward overlengthening the femur. This same principle can be applied to limb-reduction surgery, where in certain circumstances, one may choose to preferentially shorten the tibia. Clinical Relevance: This is the first study to report long-term consequences of lower extremity segment disproportion.

Femoral Version and Tibial Torsion are Not Associated With Hip or Knee Arthritis in a Large Osteological Collection.

Background: Tibial torsion and femoral anteversion are common rotational abnormalities in children, and their courses are most often benign and self-resolving. Although neither usually requires surgical treatment, the decision to perform a derotational osteotomy is usually based on the degree of functional impairment. Neither condition is thought to influence the development of osteoarthritis of the hip or knee; however, to date there have been no large scale studies confirming this. Methods: Tibial torsion and femoral version in 1158 cadaveric tibiae and femora were measured using a camera setup based on previously described radiographic landmarks. Any specimens with obvious traumatic, rheumatic, or metabolic abnormalities were excluded. Degenerative joint disease of the hip and knee were each graded from 0 to 6. Correlations between tibial torsion, femoral version, age, race, and sex with osteoarthritis of the hip and knee joints were evaluated with multiple regression analysis. Results: The mean and SDs of tibial torsion and femoral anteversion were 7.9±8.8 and 11.4±12.0 degrees, respectively. African Americans had significantly increased tibial torsion (5.1±8.7 vs. 9.2±8.5 degrees, P<0.0005) and greater femoral anteversion (14.1±11.9 vs. 10.2±11.8 degrees, P<0.0005) compared with whites. The average grades for hip and knee osteoarthritis were 3.1±1.4 and 2.7±1.4. Using multiple regression analysis neither tibial torsion nor femoral version were independent predictors of hip or knee arthritis (P>0.05 for all). Discussion: This study confirmed previously reported differences in the rotational profiles between races and sexes. However, neither tibial torsion nor femoral anteversion had a significant influence on the development of arthritis of the hip or knee. Clinical Relevance: These results support the practice of treating tibial torsion and femoral anteversion based on the symptomatology of the patient. Parents of asymptomatic children can be reassured that long-term consequences are unlikely.

Are Readmissions After THA Preventable

BackgroundReadmissions after total joint arthroplasty have become a key quality measure in elective surgery in the United States. The Affordable Care Act includes the Hospital Readmission Reduction Program, which calls for reduced payments to hospitals with excessive readmissions. This policy uses a method to determine excess readmission ratios and calculate readmission payment adjustments to hospitals, however, it is unclear whether readmission rates are an effective quality metric. The reasons or conditions associated with readmission after elective THA have been well established but the extent to which readmissions can be prevented after THA remains unclear.Questions/purposes(1) Are unplanned readmissions after THA associated with orthopaedic or medical causes? (2) Are these readmissions preventable? (3) When during the course of aftercare are orthopaedic versus medical readmissions more likely to occur?MethodsWe retrospectively evaluated all 1096 elective THAs for osteoarthritis performed between January 1, 2011 and June 30, 2014 at a major academic medical center. Of those, 69 patients (6%) who met inclusion criteria were readmitted in our healthcare system within 90 days of discharge after the index procedure during the study period. Fifty patients were readmitted within 30 days of discharge after the index procedure (5%). We defined a readmission as any unplanned inpatient or observation status admission to the hospital spanning at least one midnight. A panel of physicians not involved in the care of these patients used available criteria and existing consensus guidelines to evaluate the medical records, radiographs, and operative reports to identify whether the underlying reason for readmission was orthopaedic versus medical. They subsequently were classified as either nonpreventable or potentially preventable readmissions, based on any care that may have occurred during the index hospitalization. To make such determinations, consensus specialty society guidelines were used whenever possible for each readmission diagnosis.ResultsA total of 50 of 1096 patients (5% of those who underwent THA during the period in question) were readmitted within 30 days and 69 of 1096 (6%) were readmitted within 90 days of their index procedures. Thirty-one patients were readmitted for orthopaedic reasons (31/69; 45%) and 38 of 69 were readmitted for medical reasons (55%). Three readmissions (three of 69; 4%) were identified as potentially preventable. Of these potentially preventable readmissions, one was orthopaedic (hip dislocation) and two were medical. Thirty-day readmissions were more likely to be orthopaedic than 90-day readmissions (odds ratio, 4.06; 95% CI, 1.18–13.96; p = 0.026).ConclusionsUsing a panel of expert reviewers, available existing criteria, and consensus methodology, it appears only a small percentage of readmissions after THA are potentially preventable. Orthopaedic readmissions occur earlier during the postoperative course. Currently, existing policies and readmission penalties may not serve as valuable external quality metrics. The readmission rates in our study may represent the threshold for expected readmission rates after THA. Future studies should enroll larger numbers of patients and have independent review panels in efforts to refine criteria for what constitutes preventable readmissions.Level of EvidenceLevel III, therapeutic study

Differences in Medial and Lateral Posterior Tibial Slope An Osteological Review of 1090 Tibiae Comparing Age, Sex, and Race

Background: Injuries to the anterior cruciate ligament (ACL) are common, and a number of knee morphological variables have been identified as risk factors for an ACL injury, including the posterior tibial slope (TS). However, limited data exist regarding innate population differences in the TS. Purpose: To (1) establish normative values for the medial and lateral posterior TS; (2) determine what differences exist between ages, sexes, and races; and (3) determine how internal or external tibial rotation (as occurs during sagittal knee motion) influences the stereotactic perception of the TS. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 545 cadaveric specimens (1090 tibiae) were obtained from the Hamann-Todd osteological collection. Specimens were leveled in the coronal, sagittal, and axial planes using a digital laser. Virtual representations of each bone were created with a 3-dimensional digitizer apparatus. The TS of the medial and lateral tibial plateaus were measured using techniques adapted from previous radiographic protocols. Medial and lateral TS were then again measured on 200 tibiae that were internally and externally rotated by 10° (axially). Results: The mean (±SD) medial TS was 6.9° ± 3.7° posterior, which was greater than the mean lateral TS of 4.7° ± 3.6° posterior (P < .001). Neither the medial nor lateral TS changed with age. Women had a greater mean TS compared with men on both the medial (7.5° ± 3.8° vs 6.8° ± 3.7°, respectively; P = .03) and lateral (5.2° ± 3.5° vs 4.6° ± 3.5°, respectively; P = .04) sides. Black specimens had a greater mean medial TS (8.7° ± 3.6° vs 5.8° ± 3.3°, respectively; P < .001) and lateral TS (5.9° ± 3.3° vs 3.8° ± 3.5°, respectively; P < .001) compared with white specimens. Axial rotation was shown to increase the perception of the medial and lateral TS (P < .001). Conclusion: The medial TS was shown to be greater than the lateral TS. Important sex- and race-based differences exist in the TS. This study also highlights the role of axial rotation in measuring the TS.

Psychiatric Illness Is Common Among Patients with Orthopaedic Polytrauma and Is Linked with Poor Outcomes.

BACKGROUND Psychiatric disorders are common, and their functional consequences may be underappreciated by non-mental health-care providers. There exist limited data regarding the frequency of psychiatric illness in patients who sustain orthopaedic polytrauma. The purpose of this study was to describe the prevalence of psychiatric illness in patients with orthopaedic polytrauma, to determine whether psychiatric illnesses were identified and were accommodated by trauma providers, and, finally, to investigate any associations between postoperative complications and psychiatric illness. METHODS Three hundred and thirty-two skeletally mature patients with surgically treated axial and/or femoral fractures and injuries to other body systems (Injury Severity Score of ≥ 16 points) were identified from a database at a Level-I trauma center. These included 238 men and ninety-four women with a mean value (and standard deviation) of 39 ± 16 years for age and 27 ± 12 points for the Injury Severity Score. Records were reviewed for preexisting diagnoses of psychiatric disorders. The inpatient courses and discharge recommendations regarding treatment of psychiatric illness were analyzed. Complications in the six-month postoperative period were determined by an independent committee. RESULTS Preexisting psychiatric disorders were identified in 130 patients (39.2%), including depression in seventy-four patients (22.3%) and substance abuse in fifty-six patients (16.9%). Patients managed by an orthopaedic surgery service were less likely to receive their home psychiatric medications while hospitalized (p = 0.001) and were less likely to receive instructions for psychiatric follow-up at discharge (p = 0.087). Postoperative complications occurred in sixty-six patients (19.9%) overall; depression was an independent predictor of increased complications, with an odds ratio of 2.956 (95% confidence interval, 1.502 to 5.816). CONCLUSIONS Psychiatric illness was common among individuals who sustained orthopaedic polytrauma, and patients with depression had more complications. This study highlights the need for greater attention to mental health disorders in this population.

Can Vascular Injury be Appropriately Assessed With Physical Examination After Knee Dislocation

BackgroundKnee dislocations are rare injuries with potentially devastating vascular complications. An expeditious and accurate diagnosis is necessary, as failing to diagnose vascular injury can result in amputation; however, the best diagnostic approach remains controversial.Questions/purposesWe asked: (1) What patient factors are predictors of vascular injury after knee dislocation? (2) What are the diagnostic utilities of palpable dorsalis pedis or posterior tibial pulses, and the presence of an ankle-brachial index (ABI) of 0.9 or greater?MethodsA database at a Level I trauma center was queried for patients with evidence of knee dislocation, demographic information (age at the time of injury, sex, Injury Severity Score, BMI, mechanism of injury), and the presence of open injury were recorded. One-hundred forty-one patients underwent screening at initial presentation, of whom 26 (24%) underwent early vascular exploration based on an abnormal physical examination. One-hundred five (91%) of the remaining 115 patients were available at a minimum followup of 6 months (mean, 19 ± 10 months). In total, 31 unique patients were excluded, including 10 patients (7%) who were lost to followup before 6 months. Among the 110 patients who met inclusion criteria, the mean age and SD was 37 ± 13 years, and the Injury Severity Score was 15 ± 9. There were 71 males (65%). Logistic regression was used to determine independent correlates of vascular injury. The vascular examination was reviewed for the presence of a palpable pulse in the dorsalis pedis artery, the presence of a palpable pulse in the posterior tibial artery, and whether the ABI in the dorsalis pedis was 0.9 or greater. Contingency tables were generated to assess the sensitivity, specificity, and accuracy of physical examination maneuvers. The physical examination was collectively regarded as “normal” when both pulses were palpable and the ABI was 0.9 or greater. The initial physical examination as just described was considered the diagnostic test being evaluated in this study; “positive” tests were evaluated by and confirmed at vascular surgery, and 6 months clinical followup without symptoms or progressive signs of vascular injury confirmed the absence of injury in the remainder of the patients. Contingency tables were generated again to assess the sensitivity, specificity, and accuracy of the combined physical examination.ResultsIncreased BMI (odds ratio [OR], 1.077; 95% CI, 1.008–1.155; p = 0.033) and open injuries (OR, 3.366; 95% CI, 1.008–11.420; p = 0.048) were associated with vascular injury. No single physical examination maneuver had a 100% sensitivity for ruling out vascular injury. A normal physical examination (palpable pulses and ABI ≥ 0.9) had 100% sensitivity for ruling out vascular injury.ConclusionsIncreased BMI and the presence of open dislocation are associated with a greater risk for vascular injury after knee dislocation. The combination of a palpable dorsalis pedis and posterior tibial pulse combined with an ABI of 0.9 or greater was 100% sensitive for the detection of vascular injury based on clinical followup at 6 months.Level of EvidenceLevel III, diagnostic study.

Important Differences Exist in Posterior Condylar Offsets in an Osteological Collection of 1,058 Femurs

Posterior condylar offset (PCO) has important implications in total knee arthroplasty (TKA) function and design. In an osteological study of 1,058 femurs, we measured PCO using two separate techniques with a 3D digitizer. Measurements were standardized for the size of the femur. The medial PCO was greater than lateral PCO (32.6mm vs. 31.2mm, P<0.0001). In 53% of individuals, the medial PCO differed between sides by more than 2mm. Age did not affect standardized medial or lateral PCO. Compared with African-Americans, Caucasians had a larger standardized medial (1.3mm vs. 1.2mm, P=0.006) and lateral (1.1mm vs. 1.0mm, P=0.004) PCOs. The standardized medial (1.2mm vs. 1.3mm, P=0.073), and lateral (1.1mm vs. 1.1mm, P=0.098), PCO did not differ between men and women, respectively.

Capital Femoral Growth Plate Extension Predicts Cam Morphology in a Longitudinal Radiographic Study

BACKGROUND Recent evidence has suggested that cam morphology may be related to alterations in the capital femoral growth plate during adolescence. The purpose of this study was to evaluate the relationship between capital femoral growth plate extension and cam morphology in a longitudinal radiographic study. METHODS We used a historical, longitudinal radiographic collection to identify 96 healthy adolescents (54 boys and 42 girls) with at least 5 consecutive annual radiographs of the left hip including closure of the capital femoral physis. We reviewed 554 anteroposterior radiographs of the left hip to measure the anteroposterior modification of the alpha angle of Nötzli and of the superior epiphyseal extension ratio (EER), measured as the ratio of extension of the capital femoral epiphysis down the femoral neck relative to the diameter of the femoral head. Measurements were made at 3 points in femoral head maturation corresponding to the Oxford bone age (OBA) femoral head stages 5, 6, and 7/8. RESULTS There was a mean increase in the anteroposterior alpha angle (10.7° ± 14.0°) and EER (0.12 ± 0.08) between OBA stages 5 and 7/8, corresponding to maturation and closure of the capital femoral physis. There was a positive correlation between the final anteroposterior alpha angle and both the final EER (r = 0.60) and the change in the EER (r = 0.58). A receiver operating characteristic curve generated to predict an anteroposterior alpha angle of ≥78° through the EER demonstrated an area under the curve of 0.93, indicating that an increasing EER had excellent diagnostic accuracy for predicting concurrent cam morphology. CONCLUSIONS AND CLINICAL RELEVANCE Superior epiphyseal extension was directly and temporally associated with an increase in anteroposterior alpha angle and more cam-like morphology. This alteration in the capital femoral epiphysis occurred immediately before physeal closure (OBA stage 7/8). Given the association of epiphyseal extension with activities that increase shear forces across the physis, we proposed that epiphyseal extension may be an adaptive mechanism to stabilize the physis and prevent slipped capital femoral epiphysis.

Increased Pelvic Incidence is Associated With a More Coronal Facet Orientation in the Lower Lumbar Spine: A Cadaveric Study of 599 Lumbar Spines.

Study Design. An anatomic study of facet angle orientation and morphology of the lumbar spine was performed. Objective. The aim of this study was to determine how age, gender, race, and pelvic incidence (PI) correlate with facet orientation in the lumbar spine. Summary of Background Data. Lumbar facet orientation has important implications in the development of numerous pathologies of the spine, including arthritis, spondylolisthesis, and adult spinal deformity. Preliminary reports have suggested that sagittal balance of the spine may contribute to facet joint orientation. We therefore designed an anatomic study to investigate the relationship between PI and facet orientation, within the context of age, gender, and race. Methods. Five hundred ninety-nine cadaveric lumbar spines were obtained from the Hamann-Todd osteological collection. It was determined that facet angle was most reliably assessed by measuring the angle between the superior articular facet and the spinous process. Facet angles were measured bilaterally at each level from T12-L1 through L5-S1 in every specimen. Multivariate regression analysis was used to determine independent predictors of facet angle at each level. Results. Facet angle increased rostrally to caudally, from 22.6 ± 8.3° at T12-L1 to 49.1 ± 12.4° at L5-S1. Cadaver age was an independent predictor of a more sagittal facet angle at lower spinal levels. Caucasian race was an independent predictor of increasing facet angle. Increased PI had no effect on facet angle at T12-L1, L1-L2, L2-L3, or L3-L4, although was a significant predictor of more coronally oriented facet joints at L4-L5 (standardized beta 0.096, P = 0.009) and L5-S1 (standardized beta 0.079, P = 0.032). Conclusion. The results of this study provide important data regarding differences in facet angle that exists between individuals. Moreover, the results of this study suggest that facet joints do possess the ability to remodel over time, perhaps in response to perturbations of sagittal balance, osteophyte formation, or other yet to be determined factors. Level of Evidence: N/A