Inclination but not anatomical reconstruction is related with higher cobalt levels in MoM hip arthroplasty.

Metal on Metal total hip arthroplasty is associated with elevated serum cobalt levels. In this study we investigate if there is a relation between the inclination and anteversion angle of the cup and the anatomical reconstruction of the hip on the serum cobalt level. Postoperative cobalt serum levels were measured in 250 patients with the M2a-38 cup and Taperloc stem combination. On standardized radiographs inclination and anteversion angle, lower limb length, lateral offset and center of rotation distance were evaluated. A difference of more than 5 millimeter compared to the preoperative situation was considered as a non-anatomical reconstruction. For every 10 degrees increase in inclination the cobalt level increased 14% (p = 0.036). Women with the same cup inclination angle showed 34% higher cobalt levels than men (p = 0.013). No relation was found between the anteversion angle, anatomical reconstruction and the serum cobalt levels. A higher inclination of the cup leads to higher serum cobalt levels, but a non-anatomical reconstruction has no influence on serum cobalt levels.

Supination Contractures in Brachial Plexus Birth Palsy: Long-Term Upper Limb Function and Recurrence After Forearm Osteotomy or Nonsurgical Treatment.

PURPOSE: Forearm osteotomy for supination deformity in brachial plexus birth palsy (BPBP) may lead to improved function of the upper limb. However, recurrence rates are high and limit satisfactory results. METHODS: We reviewed the long-term outcome of the entire upper limb of 22 BPBP patients with a supination contracture who were treated by forearm osteotomy and compared them with an age-matched group that was treated nonsurgically (n = 28). Recurrence was defined as a passive pronation below 30°. RESULTS: The median follow-up was 5.0 years (range, 1.5-14 years). The mean passive pronation after forearm osteotomy, including patients with recurrence at follow-up, improved from -1° (SD, 9°) to 33° (SD, 48°) at final follow-up, mean active wrist extension improved from 23° (SD, 40°) to 41° (SD, 38°). An overall improvement of wrist and hand strength was present. In patients without recurrence, pronation improved to a mean of 66° (SD, 23°) at final follow-up. Recurrence of the supination contracture was present in 9 cases (41%) and was only present in patients with a single bone osteotomy. Recurrence was associated with lower age at surgery (recurrence mean, 4 [SD, 1.2] and no recurrence 8 [SD 4.5]), lower shoulder external rotation (recurrence mean, 28 [SD, 17] and no recurrence 49 [SD, 23]), and overall lower hand function at baseline. CONCLUSIONS: Forearm osteotomy improves forearm pronation and hand function. Recurrence should be considered as a potential complication after forearm osteotomy and is associated with young age and lower function of shoulder and hand. Single-bone osteotomy might also be a risk factor for recurrence. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Three-dimensional shoulder motion after teres major or latissimus dorsi tendon transfer for posterosuperior rotator cuff tears.

BACKGROUND: Teres major (TM) transfer and latissimus dorsi (LD) transfer are essential treatment options in patients with posterosuperior rotator cuff (RC) tears. The purpose of this study was to quantify shoulder kinematics before and after TM transfer and LD transfer in posterosuperior RC tear patients. METHODS: In this prospective cohort study, we quantitatively measured shoulder movements using an electromagnetic tracking device (Flock of Birds) preoperatively and 1 year after either TM (n = 13) or LD (n = 9) tendon transfer. Additional outcome measures included the Constant score (CS), patient-reported pain, and quantitative range of motion. Scapular kinematics were evaluated during arm abduction. RESULTS: By use of a quantitative assessment, forward flexion (from 87° to 106°, P = .007), abduction (from 86° to 106°, P = .010), and external rotation in abduction (from 52° to 70°, P = .019) improved. Both transfers reduced pain (from 50 to 10 mm, P < .001), and the CS improved (from 37 to 62 points, P < .001). No significant differences in postoperative improvement in pain and function were found between TM and LD tendon transfers. The TM transfer group showed increased scapular lateral rotation compared with the LD transfer group (13°; 95% confidence interval [CI], 4.8° to 21.7°; P = .003). We were unable to detect differences between TM transfer and LD transfer in the change in protraction (3.2°; 95% CI, -6.3° to 12.8°; P = .489) and posterior tilt (3.5°; 95% CI, -3.5° to 10.5°; P = .313). CONCLUSION: Tendon transfer surgery resulted in an overall improvement in CS, pain relief, and quantitative range of motion in the treatment of an irreparable posterosuperior RC tear. Scapular lateral rotation gradually increased after TM transfer, reminiscent of RC function, whereas such an increase was not observed after LD transfer.

The effect of a rotator cuff tear and its size on three-dimensional shoulder motion.

BACKGROUND: Rotator cuff-disease is associated with changes in kinematics, but the effect of a rotator cuff-tear and its size on shoulder kinematics is still unknown in-vivo. METHODS: In this cross-sectional study, glenohumeral and scapulothoracic kinematics of the affected shoulder were evaluated using electromagnetic motion analysis in 109 patients with 1) subacromial pain syndrome (n=34), 2) an isolated supraspinatus tear (n=21), and 3) a massive rotator cuff tear involving the supraspinatus and infraspinatus (n=54). Mixed models were applied for the comparisons of shoulder kinematics between the three groups during abduction and forward flexion. FINDINGS: In the massive rotator cuff-tear group, we found reduced glenohumeral elevation compared to the subacromial pain syndrome (16°, 95% CI [10.5, 21.2], p<0.001) and the isolated supraspinatus tear group (10°, 95% CI [4.0, 16.7], p=0.002) at 110° abduction. Reduced glenohumeral elevation in massive rotator cuff tears coincides with an increase in scapulothoracic lateral rotation compared to subacromial pain syndrome (11°, 95% CI [6.5, 15.2], p<0.001) and supraspinatus tears (7°, 95% CI [1.8, 12.1], p=0.012). Comparable differences were observed for forward flexion. No differences in glenohumeral elevation were found between the subacromial pain syndrome and isolated supraspinatus tear group during arm elevation. INTERPRETATION: The massive posterosuperior rotator cuff-tear group had substantially less glenohumeral elevation and more scapulothoracic lateral rotation compared to the other groups. These observations suggest that the infraspinatus is essential to preserve glenohumeral elevation in the presence of a supraspinatus tear. Shoulder kinematics are associated with rotator cuff-tear size and may have diagnostic potential.

Quantitative Dixon MRI sequences to relate muscle atrophy and fatty degeneration with range of motion and muscle force in brachial plexus injury.

BACKGROUND: Assessment of muscle atrophy and fatty degeneration in brachial plexus injury (BPI) could yield valuable insight into pathophysiology and could be used to predict clinical outcome. The objective of this study was to quantify and relate fat percentage and cross-sectional area (CSA) of the biceps to range of motion and muscle force of traumatic brachial plexus injury (BPI) patients. METHODS: T1-weighted TSE sequence and three-point Dixon images of the affected and non-affected biceps brachii were acquired on a 3 Tesla magnetic resonance scanner to determine the fat percentage, total and contractile CSA of 20 adult BPI patients. Regions of interest were drawn by two independent investigators to determine the inter-observer reliability. Paired Students' t-test and multivariate analysis were used to relate fat percentage, total and contractile CSA to active flexion and biceps muscle force. RESULTS: The mean fat percentage 12±5.1% of affected biceps was higher than 6±1.0% of the non-affected biceps (p<0.001). The mean contractile CSA 8.1±5.1cm2 of the affected biceps was lower than 19.4±4.9cm2 of the non-affected biceps (p<0.001). The inter-observer reliability was excellent (ICC 0.82 to 0.96). The contractile CSA contributed most to the reduction in active flexion and muscle force. CONCLUSION: Quantitative measurement of fat percentage, total and contractile CSA using three-point Dixon sequences provides an excellent reliability and relates with active flexion and muscle force in BPI.

Subacromial anaesthetics increase asymmetry of scapular kinematics in patients with subacromial pain syndrome.

BACKGROUND: Subacromial pain syndrome (SAPS) and scapular dyskinesis are closely associated, but the role of pain is unknown. We hypothesized that pain results in asymmetrical scapular kinematics, and we expected more symmetrical kinematics after infiltration of subacromial anaesthetics. OBJECTIVE: To investigate the effect of subacromial anaesthetics on scapular kinematics in patients with SAPS. DESIGN: Observational cohort study. METHODS: We evaluated shoulder kinematics in 34 patients clinically and radiologically (magnetic resonance arthrography) identified with unilateral SAPS using three-dimensional electromagnetic motion analysis (Flock of Birds). Scapular internal rotation, upward rotation and posterior tilt of the affected shoulder were compared with the kinematics of the unaffected shoulder and following subacromial anaesthetics. Additionally, the association of pain (Visual Analogue Scale, VAS) and scapular rotation was analysed. RESULTS: Compared with the contralateral healthy shoulder, 5° more (95% CI 0.4-9.7, p = 0.034) scapular internal rotation was observed in the affected shoulder at 110-120° of abduction. Following subacromial anaesthetics in the affected shoulder, internal rotation increased (2°, 95% CI 0.5-3.9, p = 0.045) and posterior tilt decreased (3°, 95% CI 1.5-5.0, p = 0.001) at 110-120° of abduction. Less scapular upward rotation was significantly associated with higher pain scores before infiltration (R = 0.45, p = 0.013). CONCLUSIONS: More scapular internal rotation was observed in affected shoulders of patients with SAPS compared with unaffected shoulders. Subacromial infiltration did not restore kinematics toward symmetrical scapular motion. These findings suggest that subacromial anaesthesia is not an effective means to instantly restore symmetry of shoulder motion.

Molecular signatures of age-associated chronic degeneration of shoulder muscles.

Chronic muscle diseases are highly prevalent in the elderly causing severe mobility limitations, pain and frailty. The intrinsic molecular mechanisms are poorly understood due to multifactorial causes, slow progression with age and variations between individuals. Understanding the underlying molecular mechanisms could lead to new treatment options which are currently limited. Shoulder complaints are highly common in the elderly, and therefore, muscles of the shoulder's rotator cuff could be considered as a model for chronic age-associated muscle degeneration. Diseased shoulder muscles were characterized by muscle atrophy and fatty infiltration compared with unaffected shoulder muscles. We confirmed fatty infiltration using histochemical analysis. Additionally, fibrosis and loss of contractile myosin expression were found in diseased muscles. Most cellular features, including proliferation rate, apoptosis and cell senescence, remained unchanged and genome-wide molecular signatures were predominantly similar between diseased and intact muscles. However, we found down-regulation of a small subset of muscle function genes, and up-regulation of extracellular region genes. Myogenesis was defected in muscle cell culture from diseased muscles but was restored by elevating MyoD levels. We suggest that impaired muscle functionality in a specific environment of thickened extra-cellular matrix is crucial for the development of chronic age-associated muscle degeneration.

Three-dimensional shoulder kinematics normalize after rotator cuff repair.

BACKGROUND: Patients with a rotator cuff (RC) tear often exhibit scapular dyskinesia with increased scapular lateral rotation and decreased glenohumeral elevation with arm abduction. We hypothesized that in patients with an RC tear, scapular lateral rotation, and thus glenohumeral elevation, will be restored to normal after RC repair. METHODS: Shoulder kinematics were quantitatively analyzed in 26 patients with an electromagnetic tracking device (Flock of Birds) before and 1 year after RC repair in this observational case series. We focused on humeral range of motion and scapular kinematics during abduction. The asymptomatic contralateral shoulder was used as the control. Changes in scapular kinematics were associated with the gain in range of motion. Shoulder kinematics were analyzed using a linear mixed model. RESULTS: Mean arm abduction and forward flexion improved after surgery by 20° (95% confidence interval [CI], 2.7°-36.5°; P = .025) and 13° (95% CI, 1.2°-36.5°; P = .044), respectively. Kinematic analyses showed decreases in mean scapular protraction (ie, internal rotation) and lateral rotation (ie, upward rotation) during abduction by 3° (95% CI, 0.0°-5.2°; P = .046) and 4° (95% CI, 1.6°-8.4°; P = .042), respectively. Glenohumeral elevation increased by 5° (95% CI, 0.6°-9.7°; P = .028) at 80°. Humeral range of motion increased when scapular lateral rotation decreased and posterior tilt increased. CONCLUSIONS: Scapular kinematics normalize after RC repair toward a symmetrical scapular motion pattern as observed in the asymptomatic contralateral shoulder. The observed changes in scapular kinematics are associated with an increased overall range of motion and suggest restored function of shoulder muscles.

Large fixed-size metal-on-metal total hip arthroplasty: higher serum metal ion levels in patients with pain.

PURPOSE: Recently, concerns have arisen about metal-on-metal (MoM) total hip arthroplasty (THA). Therefore, the purpose of this cross-sectional cohort study was to describe the incidence of pain, pseudotumours, revisions and the relation between elevated metal ion levels, functional outcome and quality of life after MoM THA. METHODS: In 351 patients, 377 MoM THA with a fixed-size 38-mm head were evaluated with a mean follow-up of 30 months (range 11-58). Evaluation included pain, serum metal ions, patient-reported questionnaires (Short Form-36 [SF-36], Hip disability and Osteoarthritis Outcome Score [HOOS] and the Oxford Hip Score [OHS]) and radiological imaging. Sixteen patients did not participate in the screening. RESULTS: One hundred and eighteen (35 %) patients reported pain and showed significantly higher cobalt and chromium levels compared to patients without pain. Median serum cobalt levels were 4.4 µg/l (interquartile range [IQR] 6.6) and chromium levels were 3.6 µg/l (IQR 4.8). Patients with cobalt levels of ≤5 µg/l reported significantly better outcome on the SF-36 and HOOS. Fifty-seven pseudotumours were identified in 227 THAs. A revision rate of 19 % was observed. CONCLUSIONS: In conclusion, 35 % of the patients experienced pain after MoM THA. These patients showed significantly higher serum metal ion levels. The patient-reported questionnaires indicated significantly better outcome in patients with cobalt levels ≤5 µg/l.

The minimal detectable change of the Constant score in impingement, full-thickness tears, and massive rotator cuff tears.

HYPOTHESIS: The purpose of this study was to determine the minimal detectable change (MDC) for the Constant score in patients with impingement, a supraspinatus tear, or a massive rotator cuff (RC) tear as observed changes smaller than the MDC might be the result of measurement error. METHODS: The Constant score was recorded in a total of 180 patients, including 34 patients with impingement, 105 with supraspinatus tears, and 41 with massive RC tears. We assessed the MDC in the 3 subgroups and total group using the samples standard deviation (SD), internal consistency (Cronbach α), and standard error of the measurement. Floor and ceiling effects were also reported. RESULTS: The absolute mean Constant score was 72 (SD, 11.2) in the impingement group, 44 (SD, 14.7) in the supraspinatus tear group, and 46 (SD, 18.9) in the massive RC tear group. There were no floor and ceiling effects for the absolute Constant score. In the total group, the internal consistency was 0.8 and the standard error of the measurement was 8. The MDC was 23 points on the Constant score in the total group and 17, 18, and 23 points on the Constant score for impingement, RC tears, and massive RC tears, respectively. CONCLUSION: This study demonstrates that the MDCs of the Constant score are different in patients with impingement, supraspinatus tears, and massive RC tears. Studies reporting the Constant score should be interpreted by use of the population-specific MDC and minimal clinical important change.

Does the latissimus dorsi tendon transfer for massive rotator cuff tears remain active postoperatively and restore active external rotation?

HYPOTHESIS: The purpose of this study is to evaluate the muscle activity with surface electromyography (EMG) and the clinical outcome of the latissimus dorsi transfer. It remains unclear whether the clinical results of the latissimus dorsi transfer for massive posterosuperior rotator cuff tears are achieved either by active muscle contractions or by a passive tenodesis effect of the transfer. METHODS: Eight patients were evaluated preoperatively and at 1 year (SD, 0.1) after the latissimus dorsi transfer. Clinical evaluation of outcomes included active range of motion, Constant score, and visual analog scale (VAS) for pain and activities of daily living (ADL). Muscle activity was recorded with EMG during directional isometric abduction and adduction tasks. RESULTS: The external rotation in adduction improved from 23° to 51° (P = .03). The external rotation in abduction improved from 10° to 70° (P = .02). The mean Constant score improved from 39 to 62 postoperatively (P = .01). The VAS for pain at rest improved from 3.3 preoperatively to 0.1 (P = .02). The VAS for ADL improved from 4.9 to 2.3 (P = .05). The transferred latissimus dorsi remained active in all cases, as reflected by increased latissimus dorsi EMG activity during abduction tasks. In addition, the latissimus dorsi EMG activity shifted from preoperative antagonistic co-activation in adduction to synergistic activation in abduction. CONCLUSION: The latissimus dorsi has synergistic muscle activity after transfer. Apart from a tenodesis effect, directional muscle activity seems relevant for improved clinical outcome and pain relief. A specific gain was observed for external rotation in elevated arm positions, a motion essential for ADL tasks.

The Western Ontario rotator cuff index in rotator cuff disease patients: a comprehensive reliability and responsiveness validation study.

BACKGROUND: The Western Ontario rotator cuff index (WORC) is an increasingly applied condition-specific outcome measure for rotator cuff (RC) conditions. However, in most WORC validation studies, only a limited number of psychometric properties are studied in indistinct patient groups. PURPOSE: To assess psychometric properties of the WORC according to the Scientific Advisory Committee quality criteria for health questionnaires in 3 patient groups with distinct RC conditions. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: The WORC (range, 0-100; 21 items, 5 domains) was administered twice (T1, T2) in 92 patients (35 RC tears, 35 calcific tendinitis, 22 impingement). Additionally, the Constant score (CS) and the Disabilities of the Arm, Shoulder and Hand score (DASH) were recorded. Calcific tendinitis patients were reassessed 6 weeks after treatment with needling and lavage or a subacromial injection with corticosteroids (T3). We assessed floor and ceiling effects, internal consistency, test-retest reliability, precision, construct validity, minimally detectable change, and responsiveness in the diagnostic subgroups and the total group. RESULTS: Mean age was 55.0 ± 8.7 years, and 49 of 92 (53%) patients were female. Mean baseline WORC was 46.8 ± 20.4, CS was 63.9 ± 15.4, and DASH was 40.9 ± 18.6. Significant differences were found for the CS and DASH between RC tear patients (severe symptoms) and the other patients, but not for the WORC. There were no floor and ceiling effects. Internal consistency was high: the Cronbach alpha coefficient was .95. The intraclass correlation coefficient of .89 and standard error of measurement of 6.9 indicated high reproducibility. Pearson correlations of the WORC with the CS and DASH were .56 and -.65, respectively (both P < .001). At T3, total WORC improved significantly (mean change, 18.8; 95% confidence interval, 11.3-26.2). Correlations of the WORC change scores with CS and DASH changes were .61 and -.84, respectively (both P < .001). Effect size was 0.96, with a standardized response mean of 0.91, indicating good responsiveness. CONCLUSION: Applied to a variety of RC patients, the WORC had high internal consistency, moderate to good construct validity, high test-retest reliability, and good responsiveness. These findings support the use of the WORC as a condition-specific self-reported outcome measure in RC patients, but its validity in patients with severe symptoms needs further investigation.