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Background: All polyethylene acetabular liners wear over time, and numerous methods for calculating linear wear rates exist. The objective of this study was to compare 2-dimensional wear rates between direct, micrometer measurements and the computerized, edge-detection method using Hip Analysis Suite (HAS) 8.0.4.3., Methods: Two groups of retrieved acetabular liners from Harris-Galante Prosthesis I and Harris-Galante Prosthesis II implants in situ for more than 10 years were evaluated. Group 1 (n = 18) contained liners with both early postoperative (<6 months) and prerevision radiographs taken within 1 month of explantation. Group 2 (n = 55) included liners with only prerevision X-rays (ie, 1 radiograph for wear assessment). Average and maximum direct linear wear was calculated from thicknesses measured at 6 consistent, well-separated locations (3 in the worn and 3 in the unworn regions) using a calibrated, digital micrometer. HAS 8.0.4.3 was used to calculate 2-dimensional wear from anteroposterior pelvic radiographs., Results: Aggregate wear rates calculated by HAS were higher than those calculated by the average of direct measurements for group 1 (P = .020) and group 2 (P < .001). However, comparing the maximum direct micrometer measurements to HAS showed no difference for either group 1 (P = .351) or group 2 (P = .451). Linear regression analysis showed a strong correlation between HAS and both average and maximum direct wear measures for both groups, though the coefficient for the direct maximum measurement comparisons were closer to one, indicating a better one-to-one correspondence between HAS and direct maximum wear., Conclusion: To our knowledge, this is the first study to compare and validate 2-dimensional wear rates in polyethylene acetabular liners between direct measurements from retrieved components and a radiographic computer-assisted technique (as opposed to comparison against a phantom component). Wear rates determined by direct measurements from retrievals were consistent with computer-assisted 2-dimensional methods when comparing maximum wear measurements. In addition, a single prerevision radiograph appears to be sufficient to assess 2-dimensional in vivo wear., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: To investigate the prevalence of shoulder labral repair and utility of magnetic resonance imaging (MRI) in determining the risks of recurrent labral tearing and impact on future participation in the National Football League (NFL)., Methods: Athletes invited to the NFL Combine between 2012 and 2015 were retrospectively reviewed. Athletes with a history of labral repair and MRI of the operative shoulder at the Combine were included in the study for further analysis, excluding athletes without a history of labral repair, labral repair without MRI at the Combine, additional procedure to the operative shoulder, or athletes still undergoing rehabilitation at the time of the Combine after labral repair. All MRIs were reviewed to determine initial labral repair location, the presence of recurrent tearing, and any concomitant shoulder pathology. Prospective information on future NFL participation in regard to draft status, games played, and games started in the athlete's first NFL season after the Combine was compared between athletes with a history of labral repair with and without recurrent tearing versus all other athletes participating in the Combine., Results: A total of 132 (10.1%) athletes underwent 146 shoulder labral repair procedures before the NFL Combine, of whom 32% (n = 39 athletes, n = 46 shoulders) had recurrent labral tears on MRI. Athletes with recurrent tears were more likely to have undergone bilateral labral repairs (P = .048) and possess concomitant shoulder pathology (P < .001). Recurrent labral tearing was significantly more common in the posterior labrum in athletes with a history of posterior labral repairs (P = .032). Prospective participation in the NFL in terms of games played (P = .38) or started (P = .98) was not significantly reduced in athletes with a history of labral repair compared with those without repair. Participation was not diminished in athletes with recurrent labral tears compared with those with intact repairs or those with evidence of degenerative joint disease., Conclusions: Athletes invited to the NFL Scouting Combine with a history of bilateral repair, posterior labral repair, and concomitant shoulder pathology are at high risk of recurrent labral tearing on MRI. No significant reduction in NFL participation the year after the Combine was seen in athletes with a history of labral repair, recurrent labral tearing, or degenerative joint disease who were successfully drafted into the NFL. In athletes with a history of labral repair, assessment of labral integrity on MRI alone is not predictive of future short-term participation., Level of Evidence: Level IV, prognostic study-case series., (Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Background: Authors have recently proposed the concept of "hip-spine syndrome", however there exists limited evidence available to differentiate whether these concomitant arthritides are due to anatomic/structural causes, or systemic/metabolic effects. Exploring this relationship has important implications during the evaluation and treatment of both spine and hip disorders-a common clinical presentation of many patients. The purpose of this experiment was to investigate the individual contribution of hip arthritis towards the development of spine arthritis, with knee arthritis also being analyzed as a negative (systemic) control., Hypothesis: Hip and spine arthritis are caused by both metabolic and anatomic causes., Methods: A large, well-organized osteological database was queried, and osteoarthritis of the spine, hip, and knee joints was quantified using a validated scoring criteria. Six hundred and twenty-five specimens were chosen for analysis. Multivariate linear regression models were created to quantify the independent contributions of age, gender, race, height, and arthritis of the spine and hip joints., Results: Age was the strongest predictor of arthritis at each site (standardized betas>0.281, P<0.001 for all). Hip arthritis was a stronger predictor of spine arthritis than was knee arthritis (standardized betas 0.215 and 0.155, respectively, P<0.001 for both). Spine arthritis was also a stronger predictor of hip arthritis than was knee arthritis (standardized betas 0.232 and 0.173, P<0.001 for both)., Conclusions: Anatomic/structural influences about the lumbosacral-pelvic junction contribute towards the development of arthritis that is separate from any systemic/metabolic effects. Surgeons performing total hip arthroplasty should remain aware of these relationships, although future research is necessary regarding optimal surgical treatment of these patients., Level of Evidence: N/A (cadaveric study)., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Purpose: Degenerative joint disease of the lumbar spine is a pervasive problem in healthcare; however, its aetiology and risk factors remain poorly defined. There have been recent attempts to correlate the anatomic parameters of facet angle and pelvic incidence with spine osteoarthritis, although data remains limited. The purpose of this experiment was to determine how age, gender, race, facet angle, tropism, and pelvic incidence correlate to facet joint osteoarthritis in the lumbar spine., Methods: A total of 576 cadaveric lumbar spines were obtained. Using validated techniques, facet angle, tropism, and pelvic incidence were measured. Osteoarthritis of the lumbar spines was graded from 0-4 at each level. Correlations between osteoarthritis and age, gender, facet angle, tropism, and pelvic incidence were evaluated with regression analysis., Results: Facet angle became more coronally oriented, and facet tropism increased from L1-L2 to L5-S1. Arthritis was highest at the L4-L5 joint (2.2 ± 1.1), compared to the L5-S1 (2.1 ± 1.1), L3-L4 (1.9 ± 1.1), L2-L3 (1.5 ± 1.0) and L1-L2 (1.0 ± 1.0) joints (p < 0.001). Age was the strongest predictor of arthritis at all levels (standardized betas 0.342 through 0.494, p < 0.001). Correlations between gender, race and osteoarthritis were not significant at any level. A decreased facet angle was predictive of increased arthritis at each joint level (standardized betas -0.091 through -0.153, p < 0.05 for all). Tropism was a predictor of increased arthritis at caudal levels. Pelvic incidence was a predictor of increased arthritis at L3-L4 (standardized beta 0.080, p = 0.02), L4-L5 (standardized beta 0.081,p = 0.02), and L5-S1 (standardized beta 0.100, p = 0.01)., Conclusions: Facet arthritis was correlated with a more sagittal orientation of the facet joints, increased tropism, and perturbations of pelvic incidence.

Purpose: We studied a large osteological collection for differences in knee rotation based upon the presence or absence of a large cam deformity of the proximal femur., Methods: We obtained 357 matched tibiae and femora from the Hamann-Todd Osteological Collection and measured: femoral head-neck alpha angle, anteroposterior axis (or Whiteside's line) at the distal femur relative to the posterior condylar axis, and position of the tibial tubercle with respect to the posterior condylar axis of the proximal tibia. We then divided these specimens into two groups based upon alpha angle <45° (Group 1, n = 73) or alpha angle >60° (Group 2, n = 122) and performed an independent samples t-test to evaluate for differences in measured parameters between groups using this subset of specimens., Results: The mean alpha angles in Group 1 and 2 were 40.9° ± 3.3° and 67.0° ± 5.6°, respectively. Whiteside's line was externally rotated with respect to the posterior femoral condylar axis by a mean of 1.8° ± 6.8° in Group 1, vs. 3.0° ± 3.7° in Group 2 (p = 0.03). The tibial tubercle was externally rotated by a mean of 19.4° ± 6.8° in Group 1, versus 16.6° ± 5.1° in Group 2 (p = 0.003)., Conclusions: Specimens with femoral head-neck alpha angle >60° demonstrated greater external rotation of the distal femur and a more internally-rotated tibial tubercle compared to specimens with an alpha angle <45°. Differences in anatomic characteristics of the knee may play a role in the development of patellofemoral pain in patients with a large cam deformity.

Purpose: To examine the prevalence and impact of athletic pubalgia (AP) surgery in elite American football athletes participating in the National Football League (NFL) Combine., Methods: Results from 1,311 athletes participating in the Combine from 2012 to 2015 were evaluated. Athletes with a history of AP repair were identified using the NFL Combine Database. Athlete history and available imaging was reviewed. NFL performance based on draft status, games played, games started, and current status in the NFL was gathered using publicly available databases. Statistical analysis was performed to detect for significant associations between athlete history and NFL performance in the presence of AP repair and pelvic pathology on postsurgical magnetic resonance imaging (MRI)., Results: AP repair was identified in 4.2% (n = 55) of athletes. MRI was performed in 35% (n = 19 of 55) with AP repair, of which 53% (n = 10 of 19) had positive pathology. Athletes with repair were not at risk of playing (P = .87) or starting (P = .45) fewer regular season games, going undrafted (P = .27), or not being on an active NFL roster (P = .51). Compared with athletes with negative imaging findings, positive pathology on MRI did not have a significant impact on games played (P = .74), games started (P = .48), draft status (P = .26), or being on an active roster (P = .74). Offensive linemen (P = .005) and athletes with a history of repair within 1 year of the Combine (P = .03) had a significantly higher risk of possessing positive pathology on MRI., Conclusions: Athletes with a history of successful AP surgery invited to the NFL Combine and those with persistent pathology on MRI are not at increased risk for diminished performance in the NFL. Offensive linemen and athletes less than 1 year out from surgery have a higher risk for positive MRI findings at the pubic symphysis., Level of Evidence: Level IV, prognostic study-case series., (Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Background: Posterior condylar offset (PCO) and posterior tibial slope (PTS) have critical consequences in total knee arthroplasty, especially with regards to sagittal plane balancing. However, there has only been limited investigation into the functional consequences of each, and there have only been anecdotal observations regarding any associations between PCO and PTS., Methods: In a large osteological study of 1138 knees, standardized measurements of PCO and PTS were taken using previously described techniques on specimens of different age, race, and gender. Multiple linear regression was performed to determine the independent predictors of medial and lateral PTS., Results: Mean standardized medial PCO was greater than lateral PCO (1.22 ± 0.16 vs 1.15 ± 0.19 mm, P < .001) and medial PTS was greater than lateral PTS (7.3 ± 3.8° vs 5.7 ± 3.7°, P < .001). Decreasing PCO, female gender, and African-American race were associated with both increased medial and lateral PTS. Neither age nor femoral length correlated with medial or lateral PTS., Conclusion: These data are the first to quantify that an inverse correlation between PCO and PTS exists. This relationship represents an important area for future biomechanical and clinical studies., (Copyright © 2016 Elsevier Inc. All rights reserved.)

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.

Purpose: Pelvic incidence is a position- and posture-independent parameter used to quantify sagittal balance of the spine, sacrum, pelvis and hips. Its functional consequences have been associated with a number of different pathologies of the spine. However, there exists considerable controversy over which demographic features contribute to the development of pelvic incidence., Methods: 880 cadaveric skeletons from the Hamann-Todd Osteological Collection were obtained. The innominate bones and sacrum were reconstructed, and pelvic incidence was measured using a previously validated technique. Specimens with obvious fracture, infection, or rheumatologic conditions were excluded from study. Descriptive data of age at the time of death, gender, race and height were collected., Results: The average pelvic incidence was 46.0° ± 11.0°. Pelvic incidence did not change with age (r = 0.026, p = 0.288). There was no difference in pelvic incidence measurements between females and males (47.2° ± 13.8° vs. 45.8° ± 10.4°, respectively; p = 0.257), although this analysis was under-powered. Pelvic incidence was higher in African-Americans compared to Caucasians (48.9° ± 11.0° vs. 44.9° ± 10.8°; p = 0.001). There was no association between height and pelvic incidence (r = -0.042, p = 0.164)., Conclusions: This study represents the largest single cohort of pelvic incidence measurements reported in the literature. Our data suggest that pelvic incidence does not change with age or height, although racial differences do exist. As spine care providers increasingly rely on pelvic incidence as an important means to quantify sagittal balance, the normative data provided herein will provide an essential reference.

Purpose: To examine a large osteological collection to assess the relations between the well-described means of quantifying cam deformities of the proximal femur-alpha angle (AA) and anterior femoral neck offset (AFNO)-and osteoarthritis of the lumbar spine., Methods: AA and AFNO were measured on paired femurs of 550 well-preserved cadaveric skeletons by use of standardized cephalocaudal digital photographs. Degenerative disease of these specimens' lumbar spines was graded from 0 to 4 with a validated grading system. Proximal femurs showing obvious arthritic changes such as lipping or osteophytes were excluded. Correlations between AA and spine osteoarthritis (SOA), as well as between AFNO and SOA, were evaluated by multiple regression analysis., Results: The average age for the skeletons was 47.8 ± 16.2 years. There were 456 male and 94 female specimens. The mean AA and AFNO were 52.4° ± 11.4° and 6.8 ± 1.5 mm, respectively. The average SOA score was 2.1 ± 0.9 (0 in 31 specimens, 1 in 82, 2 in 287, 3 in 106, and 4 in 44). There was a significant correlation between increasing AA and SOA (standardized β = 0.061, P = .041). There was also a significant correlation between decreasing AFNO and SOA (standardized β = -0.067, P = .025). There was a strong correlation between age and SOA (standardized β = 0.582, P < .0005)., Conclusions: This study provides important insight into the understanding of the hip-spine connection. Although it has no way of showing a causative or clinically significant relation, this study did show that the cam-type deformity markers of increasing AA and decreasing AFNO were significantly associated with SOA in a large osteological collection., Clinical Relevance: Clinical and biomechanical studies to assess whether cam deformity in the younger individual may contribute to the accelerated development of SOA in later life are warranted., (Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

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.

Background: In treating patients with cervical myelopathy, surgical approach may be dictated by sagittal balance, highlighting the need for accurate pre-operative assessment. Magnetic Resonance Imaging (MRI) is widely-recognized for its utility in the diagnosis and surgical planning of cervical myelopathy. Plain radiographs (X-rays) are a reliable tool to assess bony alignment. However, they may not always be included in standard pre-operative evaluation, especially in an era of restricted payer-environments. Failure to appropriately acknowledge a patients' preoperative kyphotic deformity may cause the surgeon to choose a posterior-only approach, which would provide suboptimal sagittal plane correction and decompression of anterior pathology., Methods: 101 patients with cervical myelopathy with MRI and plain radiographs were identified. Cervical lordosis and kyphosis were measured using the Cobb method on standing lateral x-ray and sagittal T2-weighted MRI. CI (Ishihara) was also measured on standing lateral x-ray, and sagittal T2-weighted MRI. Bland-Altman plots were generated and used to compare subtle differences in measurement techniques and modalities. Odom's criteria were recorded., Results: The average difference between plain radiograph and MRI measurements for curvature angle was 3.5± 7.2 degrees (p< 0.001), and the average difference between plain radiograph and MRI measurements for curvature index was 1.5± 5.9 degrees (p= 0.015)., Conclusions: MRI may under-represent the respective sagittal plane deformity in patients with degenerative cervical myelopathy., Clinical Relevance: We would recommend the use of standing x-rays when considering surgical planning in all myelopathy patients. This manuscript was reviewed and approved by an institutional review board. Informed consent was not obtained because patient specific identifying information was not used. It was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.

Objectives: The spinopelvic relationship (including pelvic incidence) has been shown to influence pelvic orientation, but its potential association with femoroacetabular impingement has not been thoroughly explored. The purpose of this study was to prove the hypothesis that decreasing pelvic incidence is associated with increased risk of cam morphology., Methods: Two matching cohorts were created from a collection of cadaveric specimens with known pelvic incidences: 50 subjects with the highest pelvic incidence (all subjects > 60°) and 50 subjects with the lowest pelvic incidence (all subjects < 35°). Femoral version, acetabular version, and alpha angles were directly measured from each specimen bilaterally. Cam morphology was defined as alpha angle > 55°. Differences between the two cohorts were analysed with a Student's t-test and the difference in incidence of cam morphology was assessed using a chi-squared test. The significance level for all tests was set at p < 0.05., Results: Cam morphology was identified in 47/100 (47%) femurs in the cohort with pelvic incidence < 35° and in only 25/100 (25%) femurs in the cohort with pelvic incidence > 60° (p = 0.002). The mean alpha angle was also greater in the cohort with pelvic incidence < 35° (mean 53.7°, sd 10.7° versus mean 49.7°, sd 10.6°; p = 0.008)., Conclusions: Decreased pelvic incidence is associated with development of cam morphology. We propose a novel theory wherein subjects with decreased pelvic incidence compensate during gait (to maintain optimal sagittal balance) through anterior pelvic tilt, creating artificial anterior acetabular overcoverage and recurrent impingement that increases risk for cam morphology.Cite this article: W. Z. Morris, C. A. Fowers, R. T. Yuh, J. J. Gebhart, M. J. Salata, R. W. Liu. Decreasing pelvic incidence is associated with greater risk of cam morphology. Bone Joint Res 2016;5:387-392. DOI: 10.1302/2046-3758.59.BJR-2016-0028.R1., Competing Interests: ICMJE conflict of interest: None declared, (© 2016 Morris et al.)

A total knee arthroplasty system offers more distal femoral implant anterior-posterior (AP) sizes than its predecessor. The purpose of this study is to investigate the impact of increased size availability on an implant system's ability to reproduce the AP dimension of the native distal femur. We measured 200 cadaveric femora with the AP-sizing guides of Zimmer (Warsaw, IN) NexGen (8 sizes) and Zimmer Persona (12 sizes) total knee arthroplasty systems. We defined "size deviation" as the difference in the AP dimension between the anatomic size of the native femur and the closest implant size. We defined satisfactory reproduction of distal femoral dimensions as < 1 mm difference between the implant and native femur size. The NexGen system was associated with a mean 0.46 mm greater implant size deviation than Persona (p < 0.001). When using a 1 mm size deviation as a cutoff for satisfactory replication of the native distal femoral anatomy, 85/200 specimens (42.5%) were a poor fit by NexGen, but a satisfactory fit by Persona. Only 1/200 specimens (0.5%) was a poor fit by Persona, but a satisfactory fit by NexGen (p < 0.001). The novel knee system with 12 versus 8 sizes reproduces the AP dimension of the native distal femur more closely than its predecessor. Further study is needed to determine the clinical impact of these differences., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

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., (Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.)

Purpose: To investigate the relation between cam, acetabular version, and pelvic incidence., Methods: This was a retrospective analysis of 65 patients with symptomatic hip pain and radiographic signs of femoroacetabular impingement (FAI). Twenty-seven patients were used as a control. All patients received a CT scan of the pelvis that included the sacral endplate. Alpha angle, acetabular version, and pelvic incidence (PI) were measured on 2D CT. Patients were then assigned to 1 of 4 groups: control, cam (alpha angle > 55°, version > 15°), retroverted (alpha angle < 55°, version < 15°), or mixed (alpha angle > 55°, version < 15°)., Results: The PI in mixed-type FAI was 46.7° ± 3.7°, which showed a statistically significant decrease from the PI of the control group, 56.1° ± 4.4° (P = .01). The PI for cam-only deformity was 50.8° ± 4.6°, and the PI for retroverted-only deformity was 51.0° ± 4.6°. Neither was statistically different from the control., Conclusions: This study suggests that mixed-type FAI may develop as a response to decreased PI. This result is consistent with previous reports showing decreased PI associated with cam and retroversion deformities. Although the cause of FAI remains controversial, the potential impact of sagittal balance of the pelvis, and specifically, decreased PI, should not be ignored., Level of Evidence: Level IV, therapeutic case series., (Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Background: Proinflammatory signaling by toll-like receptors (TLRs) likely contributes to biologic responses to wear particles causing aseptic loosening. We recently reported associations with aseptic loosening in patients with polymorphisms in the locus encoding an adapter protein specific for TLR-2 and TLR-4 known as toll/interleukin-1 receptor domain-containing adapter protein/MyD88 adapter-like (TIRAP/Mal). To directly examine the contribution of TIRAP/Mal, we tested the hypothesis that TIRAP/Mal deficiency reduces the activity of wear particles. Signaling by TLR-2 and TLR-4 through TIRAP/Mal can be activated by bacterial pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide or endogenous alarmins. To distinguish between those possibilities, we tested the hypothesis that the effects of TIRAP/Mal depend on the adherence of bacterial PAMPs to the particles., Methods: In vitro mRNA levels and secretion of tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 were measured after incubating wild-type and TIRAP/Mal(-/-) macrophages in the presence or absence of titanium particles with adherent bacterial debris, so-called endotoxin-free particles, or particles with adherent lipopolysaccharide. In vivo osteolysis was measured after implanting titanium particles on the calvaria of wild-type and TIRAP/Mal(-/-) mice., Results: TIRAP/Mal deficiency significantly inhibited the activity of titanium particles with adherent bacterial debris to stimulate in vivo osteolysis and in vitro cytokine mRNAs and secretion. Those effects are dependent on adherent PAMPs because removal of >99% of the adherent bacterial debris from the particles significantly reduced their activity and the remaining activity was not dependent on TIRAP/Mal. Moreover, adherence of highly purified lipopolysaccharide to the endotoxin-free particles reconstituted the activity and the dependence on TIRAP/Mal., Conclusions: TIRAP/Mal deficiency reduces inflammatory responses and osteolysis induced by particles with adherent PAMPs., Clinical Relevance: Our results, coupled with the genetic associations between aseptic loosening and polymorphisms within the TIRAP/Mal locus, support TLR signaling through TIRAP/Mal as one of the factors that enhances the activity of wear particles and further support the hypothesis that bacterial PAMPs likely contribute to aseptic loosening in a subset of patients., (Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.)

Objectives: Sagittal alignment of the lumbosacral spine, and specifically pelvic incidence (PI), has been implicated in the development of spine pathology, but generally ignored with regards to diseases of the hip. We aimed to determine if increased PI is correlated with higher rates of hip osteoarthritis (HOA). The effect of PI on the development of knee osteoarthritis (KOA) was used as a negative control., Methods: We studied 400 well-preserved cadaveric skeletons ranging from 50 to 79 years of age at death. Each specimen's OA of the hip and knee were graded using a previously described method. PI was measured from standardised lateral photographs of reconstructed pelvises. Multiple regression analysis was performed to determine the relationship between age and PI with HOA and KOA., Results: The mean age was 60.2 years (standard deviation (sd) 8.1), and the mean PI was 46.7° (sd 10.7°). Multiple regression analysis demonstrated a significant correlation between increased PI and HOA (standardised beta = 0.103, p = 0.017). There was no correlation between PI and KOA (standardised beta = 0.003, p = 0.912)., Conclusion: Higher PI in the younger individual may contribute to the development of HOA in later life.Cite this article: Dr J. J. Gebhart. Relationship between pelvic incidence and osteoarthritis of the hip. Bone Joint Res 2016;5:66-72. DOI: 10.1302/2046-3758.52.2000552., (© 2016 Gebhart et al.)

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 development of C5 nerve palsy after cervical decompression surgery has been well documented. The goal of this study was to determine whether preoperative spinal cord rotation could be used as a predictor of C5 palsy in patients who underwent posterior cervical decompression at C4-C6. The authors reviewed the records of 72 patients who had posterior decompression and 77 patients who had anterior decompression. With the patients undergoing anterior decompression used as a control group, magnetic resonance imaging scans were analyzed for area of the spinal cord, anterior-posterior diameter, and cord rotation relative to the vertebral body. The rate of C5 palsy was 7.3%. Average degrees of rotation were 3.83°±2.47° and 3.45°±2.23° in the anterior and posterior groups, respectively. A statistically significant association was detected between degree of rotation and C5 palsy. Point-biserial correlations were 0.58 (P<.001) and 0.60 (P<.001) in the anterior and posterior groups, respectively. With a diagnostic cutoff of 6°, the sensitivity and specificity of identifying patients with C5 palsy in the posterior group were 0.67 (95% confidence interval, 0.24-0.94) and 0.95 (95% confidence interval, 0.86-0.98), respectively. The results suggested that preoperative spinal cord rotation may be a valid predictor of C5 nerve palsy after posterior cervical decompression. With mild rotation defined as less than 6°, moderate rotation as 6° to 10°, and severe rotation as greater than 10°, the prevalence of C5 palsy in the posterior group was 2 of 65 for mild rotation, 3 of 6 for moderate rotation, and 1 of 1 for severe rotation., (Copyright 2015, SLACK Incorporated.)

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., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: The sacropelvic parameter of pelvic incidence (PI) is a position-independent anatomic parameter that regulates lumbar lordosis and pelvic orientation. While it has been extensively studied in relation to spine pathology, only a single study has correlated PI with femoroacetabular impingement (FAI)., Hypothesis: Decreased PI would be associated with an increased prevalence of cam and pincer lesions., Study Design: Controlled laboratory study., Methods: Measurements of the acetabulum, proximal femur, and sacropelvis were made bilaterally on 40 cadaveric specimens, for a total of 80 hips. Twenty specimens had the presence of bilateral cam deformities (alpha angle >55°), and 20 age- and sex-matched specimens had bilateral normal hips. Pincer lesions were defined as an anteversion <15°. Pelvic incidence and acetabular version were measured using standardized lateral photographs and a goniometer, respectively. Independent-samples t tests were performed to evaluate for differences in measured parameters between groups., Results: The mean PI was 43.1° ± 8.6° for hips with a cam lesion and 47.7° ± 9.3° for normal hips, demonstrating a significant association between decreased PI and the presence of a cam lesion (P = .02). The mean version of acetabula with pincer lesions (n = 28) was 11.4° ± 2.5°, and the mean version of normal acetabula (n = 52) was 20.1° ± 3.8°. The mean PI of hips with pincer lesions was 42.5° ± 8.5°, significantly less than that of normal hips, 47.0° ± 9.2° (P = .04)., Conclusion: This study supports a recent study that suggested patients with pincer impingement have a smaller PI than the healthy population, and it is the first to demonstrate a significant association between decreased PI and cam-type femoral deformity. Based on results of this study, further clinical study of the effects of pelvic geometry on FAI is warranted., Clinical Relevance: While the study results do not prove a causal relationship, it is theorized that the restriction of range of motion and biomechanical adaptations of the pelvis around the hip joints resulting from a smaller PI may affect hip development and FAI. The influence of mechanical factors beyond the hip joint in the development of FAI should be considered by clinicians., (© 2014 The Author(s).)

Background: Coxa magna, the asymmetrical circumferential enlargement of the femoral head, is an important sequela of pediatric disorders such as Legg-Calvé-Perthes disease. Definitions vary because of lack of controls and a scarcity of research on the distribution of the femoral head asymmetry. This study aims at defining the normal distribution of asymmetry between the left and the right femoral head and neck in the population and how demographics affect these properties. The study also looked at the distribution of side dominance (left or right)., Methods: This study measured 230 paired femurs from individuals (20 to 40 y old) distributed for sex and ethnicity. The height and weight of the individuals were also recorded. The femoral head diameter and minimal femoral neck diameter in the anteroposterior view were measured on each paired femurs. The absolute and percent differences were determined to define asymmetry., Results: Most of the population fell within 3% of asymmetry for the femoral head and 4% for the femoral neck. The maximum head percent asymmetry was 7.4%. Absolute difference in millimeters to percent asymmetry showed a ratio of 2:1 for the femoral head and 3:1 for the femoral neck. African Americans showed greater femoral head symmetry and a bias toward left-sided femoral head and neck enlargement when compared with their white counterparts., Conclusions: There was a high degree of symmetry between the left and right femoral heads and necks, which supports definitions found in the literature that define coxa magna above 10%. This study defines asymmetry in the femoral head in the normal population, which will help to define a quantitative definition of coxa magna.

Background: Estimation of size, shape, and curvature of the humeral head is important for shoulder replacement procedures and allograft transplantation, especially as we try to recreate normal anatomy. The purpose of this study was to investigate the value of various anthropometric measurements for predicting humeral head curvature., Materials and Methods: Cadaveric humeri were scanned with a 3-dimensional laser scanner. Length of the humerus, epicondylar breadth, and humeral head curvature were determined using data from the scans. A linear regression was performed for the length of the humerus, epicondylar breadth, gender, age, height, and weight. A stepwise linear regression with forward and backward substitution (α = 0.15) was performed for the most predictive variables from the initial linear regression. An equation for the prediction of humeral head radius of curvature was generated using this data., Results: The most predictive factors (R(2) > 0.5) were epicondylar breadth, height, sex, and humeral length. These 4 factors were included in a forward and backward stepwise regression. The resulting equation had an R(2) value of 0.812., Conclusion: Of the predicted measurements evaluated, patient height, maximum humeral length, epicondylar breadth, and gender were most correlated with humeral head curvature. Including these 4 factors in a linear regression model increased the R(2) value to 0.812. If only a single measurement can be used to size the humeral head curvature, patient height will give the same accuracy as epicondylar breadth and can more easily be obtained. A patient's height can help accurately predict the patient's humeral head anatomy., (Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)