"Dynamic knee valgus" - Are we measuring what we think we're measuring? An evaluation of static and functional knee calibration methods for application in gait and clinical screening tests of the overhead squat and hurdle step.

BACKGROUND: "Dynamic knee valgus" has been identified as a risk factor for significant knee injuries, however, the limits and sources of error associated with existing 3D motion analysis methods have not been well established. RESEARCH QUESTION: What effect does the use of differing static and functional knee axis orientation methods have on the observed knee angle outputs for the activities of gait, overhead squatting and a hurdle step? METHODS: A pre-existing dataset collected from one season (September 2015-May 2016) as part of a prospective observational longitudinal study was used. A secondary analysis of data for 24 male footballers, from a single British University football team, was conducted in order to evaluate the effect of static (conventional gait model) and dynamic (constrained and unconstrained mDynaKAD) methods on knee joint kinematics for flexion-extension and valgus-varus angles. RESULTS: No single calibration method consistently achieved both the highest flexion and lowest valgus angle for all tests. The constrained and unconstrained mDynaKAD methods achieved superior alignment of the knee medio-lateral axis compared to the conventional gait model, when the movement activity served as its own calibration. The largest mean difference between methods for sagittal and coronal plane kinematics was less than 4° and 14° respectively. Cross-talk could not account for all variation within the results, highlighting that soft tissue artefact, associated with larger muscle volumes and movements, can influence kinematics results. SIGNIFICANCE: When considering the trade-off between achieving maximum flexion and minimal valgus angle, the results indicate that the mDynaKAD methods performed best when the selected movement activity served as its own calibration method for all activities. Clinical decision making processes obtained through use of these methods should be considered in light of the model errors associated with cross-talk and effect of soft tissue artefact.

The Relationship Between Early-Stage Knee Osteoarthritis and Lower-Extremity Alignment, Joint Laxity, and Subjective Scores of Pain, Stiffness, and Function.

CONTEXT: Knee osteoarthritis (OA) is a debilitating disease that affects an estimated 27 million Americans. Changes in lower-extremity alignment and joint laxity have been found to redistribute the medial and/or lateral loads at the joint. However, the effect that changes in anteroposterior knee-joint laxity have on lower-extremity alignment and function in individuals with knee OA remains unclear. OBJECTIVE: To examine anteroposterior knee-joint laxity, lower-extremity alignment, and subjective pain, stiffness, and function scores in individuals with early-stage knee OA and matched controls and to determine if a relationship exists among these measures. DESIGN: Case control. SETTING: Sports-medicine research laboratory. PARTICIPANTS: 18 participants with knee OA and 18 healthy matched controls. INTERVENTION: Participants completed the Western Ontario McMaster (WOMAC) osteoarthritis questionnaire and were tested for total anteroposterior knee-joint laxity (A-P) and knee-joint alignment (ALIGN). MAIN OUTCOME MEASURES: WOMAC scores, A-P (mm), and ALIGN (°). RESULTS: A significant multivariate main effect for group (Wilks' Λ = 0.30, F7,26 = 8.58, P < .0001) was found. Knee-OA participants differed in WOMAC scores (P < .0001) but did not differ from healthy controls on ALIGN (P = .49) or total A-P (P = .66). No significant relationships were identified among main outcome measures. CONCLUSION: These data demonstrate that participants with early-stage knee OA had worse pain, stiffness, and functional outcome scores than the matched controls; however, ALIGN and A-P were no different. There was no association identified among participants' subjective scores, ALIGN, or A-P measures in this study.

Effect of femoral anteversion on clinical outcomes after hip arthroscopy.

PURPOSE: To compare the clinical outcomes after hip arthroscopy of patients with femoral retroversion, normal femoral version, and excessive femoral anteversion. METHODS: Patients who underwent primary hip arthroscopy from August 2008 to April 2011 and underwent femoral anteversion measurement by magnetic resonance imaging/magnetic resonance arthrogram were included. The patients were divided into 3 groups: retroversion, normal version, and excessive anteversion. The normal-version group was considered to have a value within 1 SD of the mean femoral version value. Four patient-reported outcome scores and the visual analog pain score were prospectively collected with analysis performed retrospectively. RESULTS: Two hundred seventy-eight patients met the inclusion criteria. Among these patients, mean anteversion was 8.2° ± 9.3°, creating a retroversion group defined as -2° or less and an anteversion group defined as 18° or greater. There were 25 patients in the retroversion group, 219 in the normal-version group, and 34 in the excessive-anteversion group. Most labral tears were noted in the 12- to 2-o'clock range, with the main difference at the anterior 3-o'clock position, where the excessive-anteversion group showed a lower incidence of tearing (30%) than the retroversion group (73%) and normal-anteversion group (78%). Postoperatively, there was a statistically significant improvement from preoperative scores in all 3 groups and for all scores (P < .001). When the postoperative scores were compared for the 3 groups, although all scores were higher in the retroversion group than in the other 2 groups, this was not statistically significant and there were no significant differences in scores among the 3 groups (modified Harris Hip Score, P = .104; Non-Arthritic Hip Score, P = .177; Hip Outcome Score-Activities of Daily Living, P = .152; Hip Outcome Score-Sport-Specific Subscale, P = .276; visual analog scale score, P = .508). CONCLUSIONS: On the basis of patient-reported outcome scores without accounting for diagnoses and treatments, the amount of femoral anteversion does not appear to affect the clinical outcomes after hip arthroscopy. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Does Salter innominate osteotomy predispose the patient to acetabular retroversion in adulthood?

BACKGROUND: Salter innominate osteotomy has been identified as an effective additional surgery for the dysplastic hip. However, because in this procedure, the distal segment of the pelvis is displaced laterally and anteriorly, it may predispose the patient to acetabular retroversion. The degree to which this may be the case, however, remains incompletely characterized. QUESTIONS/PURPOSES: We asked, in a group of pediatric patients with acetabular dysplasia who underwent Salter osteotomy, whether the operated hip developed (1) acetabular retroversion compared with contralateral unaffected hips; (2) radiographic evidence of osteoarthritis; or (3) worse functional scores. (4) In addition, we asked whether femoral head deformity resulting from aseptic necrosis was a risk factor for acetabular retroversion. METHODS: Between 1971 and 2001, we performed 213 Salter innominate osteotomies for unilateral pediatric dysplasia, of which 99 hips (47%) in 99 patients were available for review at a mean of 16 years after surgery (range, 12-25 years). Average patient age at surgery was 4 years (range, 2-9 years) and the average age at the most recent followup was 21 years (range, 18-29 years). Acetabular retroversion was diagnosed based on the presence of a positive crossover sign and prominence of the ischial spine sign at the final visit. The center-edge angle, acetabular angle of Sharp, and acetabular index were measured at preoperative and final visits. Contralateral unaffected hips were used as controls, and statistical comparison was made in each patient. Clinical findings, including Harris hip score (HHS) and the anterior impingement sign, were recorded at the final visit. RESULTS: Patients were no more likely to have a positive crossover sign in the surgically treated hips (20 of 99 hips [20%]) than in the contralateral control hips (17 of 99 hips [17%]; p = 0584). In addition, the percentage of positive prominence of the ischial spine sign was not different between treated hips (22 of 99 hips [22%]) and contralateral hips (18 of 99 hips [18%]; p = 0.256). Hips that had a positive crossover or prominence of the ischial spine sign in the operated hips were likely also to have a positive crossover sign or prominence of the ischial spine sign in the unaffected hips (16 of 20 hips [80%] crossover sign, 17 of 22 hips [77%] prominence of the ischial spine sign). At the final visit, five hips (5%) showed osteoarthritic change; one of the five hips (20%) showed positive crossover and prominence of the ischial spine signs, and the remaining four hips showed negative crossover and prominence of the ischial spine signs. There was no significant difference in HHS between the crossover-positive and crossover-negative patient groups nor in the prominence of the ischial spine-positive and prominence of the ischial spine-negative patient groups (crossover sign, p = 0.68; prominence of the ischial spine sign, p = 0.54). Hips with femoral head deformity (25 of 99 hips [25%]) were more likely to have acetabular retroversion compared with hips without femoral-head deformity (crossover sign, p = 0.029, prominence of the ischial spine sign, p = 0.013). CONCLUSIONS: Our results suggest that Salter innominate osteotomy does not consistently cause acetabular retroversion in adulthood. We propose that retroversion of the acetabulum is a result of intrinsic development of the pelvis in each patient. A longer-term followup study is needed to determine whether retroverted acetabulum after Slater innominate osteotomy is a true risk factor for early osteoarthritis. Femoral head deformity is a risk factor for subsequent acetabular retroversion. LEVEL OF EVIDENCE: Level III, therapeutic study.

Posterior shoulder instability: does glenoid retroversion predict recurrence and contralateral instability?

PURPOSE: To determine whether glenoid retroversion is a predictor of posterior shoulder instability, contralateral instability, or recurrent instability in patients with traumatic, contact-related posterior shoulder instability. METHODS: Patients who underwent shoulder stabilization by 2 senior orthopaedic sport surgeons were identified retrospectively. Patients with a connective tissue disorder, multidirectional instability, or non-trauma-induced pathology were excluded. Patients with a glenoid lesion involving greater than 25% of the glenoid or an engaging humeral lesion were also excluded. Thus patients with a traumatic injury and a magnetic resonance imaging scan available for review were included. Magnetic resonance imaging scans were reviewed, and glenoid version was measured using the glenoid vault method. Charts were reviewed for epidemiologic data, recurrent instability requiring reoperation, evidence of glenoid/humeral bone lesions, and contralateral shoulder instability requiring surgery. Both recurrence and contralateral injury were defined based on having repeat surgery. RESULTS: We identified 143 patients who met the inclusion criteria. Twenty-eight patients had posterior instability, whereas 115 patients had anterior instability. Patients with posterior instability had significantly more glenoid retroversion than patients with anterior instability (-15.4° ± 5.14° v -12.1° ± 6.9°; P < .016). Patients with retroversion of more than -16° showed a higher incidence of contralateral injuries (P < .036). However, no difference in postsurgical recurrent instability was noted. CONCLUSIONS: Our data show that patients with posterior instability have a higher incidence of having a retroverted glenoid. Patients with increased retroversion showed increased posterior contralateral instability. Furthermore, patients with posterior instability and no humeral bone lesions may be more likely to incur contralateral injuries than those with humeral lesions. These data suggest that glenoid version and concomitant injury patterns may be used to help physicians counsel patients on their future risks of contralateral injury. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

The management of acetabular retroversion with reverse periacetabular osteotomy.

Retroversion of the acetabulum is a structural disorder in which the acetabulum opens in a posterolateral direction instead of an anterolateral direction in the sagittal plane. The limitations in range of motion (flexion and internal rotation) conferred by sectorial overcoverage resulting from retroversion may predispose patients to femoroacetabular impingement. If left untreated in a symptomatic patient, femoroacetabular impingement can lead to early hip arthritis. In a symptomatic patient with preserved articular cartilage, treatment of the structural disorder may be warranted to alleviate pain and limit the progression of hip disease. It is helpful to review the clinical diagnosis, radiographic interpretation, and management of acetabular retroversion, including treatment with reverse periacetabular osteotomy.

Femoroacetabular impingement predisposes to traumatic posterior hip dislocation.

BACKGROUND: Traumatic posterior hip dislocation in adults is generally understood to be the result of a high-energy trauma. Aside from reduced femoral antetorsion, morphologic risk factors for dislocation are unknown. We previously noticed that some hips with traumatic posterior dislocations had evidence of morphologic features of femoroacetabular impingement (FAI), therefore, we sought to evaluate that possibility more formally. QUESTIONS/PURPOSES: We asked whether hips with a traumatic posterior hip dislocation present with (1) a cam-type deformity and/or (2) a retroverted acetabulum. METHODS: We retrospectively compared the morphologic features of 53 consecutive hips (53 patients) after traumatic posterior hip dislocation with 85 normal hips (44 patients) based on AP pelvic and crosstable axial radiographs. We measured the axial and the lateral alpha angle for detection of a cam deformity and the crossover sign, ischial spine sign, posterior wall sign, retroversion index, and ratio of anterior to posterior acetabular coverage to describe the acetabular orientation. RESULTS: Hips with traumatic posterior traumatic dislocation were more likely to have cam deformities than were normal hips, in that the hips with dislocation had increased axial and lateral alpha angles. Hips with posterior dislocation also were more likely to be retroverted; dislocated hips had a higher prevalence of a positive crossover sign, ischial spine sign, and posterior wall sign, and they had a higher retroversion index and increased ratio of anterior to posterior acetabular coverage. CONCLUSIONS: Hips with posterior traumatic dislocation typically present with morphologic features of anterior FAI, including a cam-type deformity and retroverted acetabulum. An explanation for these findings could be that the early interaction between the aspherical femoral head and the prominent acetabular rim acts as a fulcrum, perhaps making these hips more susceptible to traumatic dislocation.

Pelvic morphology differs in rotation and obliquity between developmental dysplasia of the hip and retroversion.

BACKGROUND: Developmental dysplasia of the hip (DDH) and acetabular retroversion represent distinct acetabular pathomorphologies. Both are associated with alterations in pelvic morphology. In cases where direct radiographic assessment of the acetabulum is difficult or impossible or in mixed cases of DDH and retroversion, additional indirect pelvimetric parameters would help identify the major underlying structural abnormality. QUESTIONS/PURPOSES: We asked: How does DDH and retroversion differ with respect to rotation and coronal obliquity as measured by the pelvic width index, anterior inferior iliac spine (AIIS) sign, ilioischial angle, and obturator index? And what is the predictive value of each variable in detecting acetabular retroversion? METHODS: We reviewed AP pelvis radiographs for 51 dysplastic and 51 retroverted hips. Dysplasia was diagnosed based on a lateral center-edge angle of less than 20° and an acetabular index of greater than 14°. Retroversion was diagnosed based on a lateral center-edge angle of greater than 25° and concomitant presence of the crossover/ischial spine/posterior wall signs. We calculated sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve for each variable used to diagnose acetabular retroversion. RESULTS: We found a lower pelvic width index, higher prevalence of the AIIS sign, higher ilioischial angle, and lower obturator index in acetabular retroversion. The entire innominate bone is internally rotated in DDH and externally rotated in retroversion. The areas under the ROC curve were 0.969 (pelvic width index), 0.776 (AIIS sign), 0.971 (ilioischial angle), and 0.925 (obturator index). CONCLUSIONS: Pelvic morphology is associated with acetabular pathomorphology. Our measurements, except the AIIS sign, are indirect indicators of acetabular retroversion. The data suggest they can be used when the acetabular rim is not clearly visible and retroversion is not obvious. LEVEL OF EVIDENCE: Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.