Frédéric Balg

Prospective heterotopic ossification progenitors in adult human skeletal muscle

Skeletal muscle has strong regenerative capabilities. However, failed regeneration can lead to complications where aberrant tissue forms as is the case with heterotopic ossification (HO), in which chondrocytes, osteoblasts and white and brown adipocytes can arise following severe trauma. In humans, the various HO cell types likely originate from multipotent mesenchymal stromal cells (MSCs) in skeletal muscle, which have not been identified in humans until now. In the present study, adherent cells from freshly digested skeletal muscle tissue were expanded in defined culture medium and were FACS-enriched for the CD73(+)CD105(+)CD90(-) population, which displayed robust multilineage potential. Clonal differentiation assays confirmed that all three lineages originated from a single multipotent progenitor. In addition to differentiating into typical HO lineages, human muscle resident MSCs (hmrMSCs) also differentiated into brown adipocytes expressing uncoupling protein 1 (UCP1). Characterizing this novel multipotent hmrMSC population with a brown adipocyte differentiation capacity has enhanced our understanding of the contribution of non-myogenic progenitor cells to regeneration and aberrant tissue formation in human skeletal muscle.

Validation of the Instability Shoulder Index Score in a Multicenter Reliability Study in 114 Consecutive Cases

Background: Anterior shoulder stabilization surgery with the arthroscopic Bankart procedure can have a high recurrence rate in certain patients. Identifying these patients to modify outcomes has become a focal point of research. Purpose: The Instability Shoulder Index Score (ISIS) was developed to predict the success of arthroscopic Bankart repair. Scores range from 0 to 10, with higher scores predicting a higher risk of recurrence after stabilization. The interobserver reliability of the score is not known. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: This is a prospective multicenter (North America and Europe) study of patients suffering from shoulder instability and waiting for stabilization surgery. Five pairs of independent evaluators were asked to score patient instability severity with the ISIS. Patients also completed functional scores (Western Ontario Shoulder Instability Index [WOSI], Disabilities of the Arm, Shoulder and Hand–short version [QuickDASH], and Walch-Duplay test). Data on age, sex, number of dislocations, and type of surgery were collected. The test-retest method and intraclass correlation coefficient (ICC: >0.75 = good, >0.85 = very good, and >0.9 = excellent) were used for analysis. Results: A total of 114 patients with anterior shoulder instability were included, of whom 89 (78%) were men. The mean age was 28 years. The ISIS was very reliable, with an ICC of 0.933. The mean number of dislocations per patient was higher in patients who had an ISIS of ≥6 (25 vs 14; P = .05). Patients who underwent more complex arthroscopic procedures such as Hill-Sachs remplissage or open Latarjet had higher preoperative ISIS outcomes, with a mean score of 4.8 versus 3.4, respectively (P = .002). There was no correlation between the ISIS and the quality-of-life questionnaires, with Pearson correlations all >0.05 (WOSI = 0.39; QuickDASH = 0.97; Walch-Duplay = 0.08). Conclusion: Our results show that the ISIS is reliable when used in a multicenter study with anterior traumatic instability populations. There was no correlation between the ISIS and the quality-of-life questionnaires, but surgical decisions reflected its increased use.

Functional movement screen test: A reliable screening test for young elite ice hockey players

OBJECTIVES To determine inter-rater and intra-rater reliability of the Functional Movement Screen (FMS) test among young elite hockey players. DESIGN Reliability study. SETTING Inter-rater reliability was evaluated by two raters in the field. All performances were videotaped. Two other raters evaluated the videos once and then again 6 weeks later to determine intra-rater reliability. A weighted kappa statistic was used to analyze intra-rater and inter-rater reliability of each FMS sub-test, while an intra-class correlation coefficient (ICC) was calculated for the total score. PARTICIPANTS Twenty-eight male hockey players aged 13-16. MAIN OUTCOME FMS total and sub-tests scores. RESULTS The video raters demonstrated excellent intra-rater reliability for the total score, with an ICC of 0.96 (95% CI; 0.92-0.98) and 0.96 (95% CI; 0.91-0.98). The field raters achieved excellent inter-rater reliability for the total score, with an ICC of 0.96 (95% CI; 0.92-0.98). Sub-test analysis showed good agreement among all four raters for five of the seven main sub-tests. CONCLUSION FMS is a reliable test for young elite hockey players. Further research should be done to assess the predictive validity of the FMS test within this population so that physiotherapists may eventually use it as an injury prevention tool.

Validity and Reliability of the iPhone to Measure Rib Hump in Scoliosis

Study Design: This was a prospective blinded validity and reliability analysis. Objective: The aim of this study was validation and reliability evaluation of the Scoligauge iPhone app. Background: The scoliometer is used to clinically measure the rib hump in scoliosis as a means to evaluate the axial trunk rotation. The increasing availability of smartphone with built-in accelerometer led to the development of a vast number of applications to measure angles. Of these, the Scoligauge mimics a scoliometer. The aim of this study was to compare the validity of the Scoligauge iPhone application without an associated adapter with the traditional scoliometer and to test the reliability of the application in a clinical setting. Methods: Two observers measured the rib hump deformity on 34 consecutive patients with idiopathic scoliosis with an average Cobb angle of 24.2±13.5 degrees (range, 4 to 65 degrees). Measurements were made with an iPhone without the adapter and with a scoliometer. The validity as well as the interobserver and intraobserver reliability were calculated using the intraclass coefficient (ICC) and the Bland-Altman test. Results: The mean difference between the scoliometer and the Scoligauge application was 0.4 degrees [95% confidence interval (CI) of ±3.1 degrees] with an ICC of 0.947 (P<0.001). The intraobserver and interobserver ICC were 0.961 (P<0.001) and 0.901 (P<0.001), respectively. The mean intraobserver difference was 0.0 degrees (95% CI of ±2.7 degrees) and the mean interobserver difference was 0.1 degrees (95% CI of ±4.4 degrees). Conclusions: The intraobserver and interobserver reliability of the Scoligauge iPhone app, as well as its validity compared with the scoliometer, are excellent. The mean differences between measurements are small and clinically not significant. Thus, the Scoligauge application is valid for clinical evaluation even without special adapter. Level of Evidence: Level I (Diagnostic Study).

Unravelling the effect of experimental pain on the corticomotor system using transcranial magnetic stimulation and electroencephalography.

The interaction between pain and the motor system is well-known, with past studies showing that pain can alter corticomotor excitability and have deleterious effects on motor learning. The aim of this study was to better understand the cortical mechanisms underlying the interaction between pain and the motor system. Experimental pain was induced on 19 young and healthy participants using capsaicin cream, applied on the middle volar part of the left forearm. The effect of pain on brain activity and on the corticomotor system was assessed with electroencephalography (EEG) and transcranial magnetic stimulation (TMS), respectively. Compared to baseline, resting state brain activity significantly increased after capsaicin application in the central cuneus (theta frequency), left dorsolateral prefrontal cortex (alpha frequency), and left cuneus and right insula (beta frequency). A pain-evoked increase in the right primary motor cortex (M1) activity was also observed (beta frequency), but only among participants who showed a reduction in corticospinal output (as depicted by TMS recruitment curves). These participants further showed greater beta M1-cuneus connectivity than the other participants. These findings indicate that pain-evoked increases in M1 beta power are intimately tied to changes in the corticospinal system, and provide evidence that beta M1-cuneus connectivity is related to the corticomotor alterations induced by pain. The differential pattern of response observed in our participants suggest that the effect of pain on the motor system is variable from on individual to another; an observation that could have important clinical implications for rehabilitation professionals working with pain patients.

Impact of olecranon fracture malunion: Study on the importance of PUDA (Proximal Ulna Dorsal Angulation).

PURPOSE The Proximal Ulna Dorsal Angulation (PUDA) is part of the proximal ulnas normal anatomy. The importance of restoring ulnar anatomy characteristics precisely after olecranon fracture is not known, however, failure to recreate the PUDA after surgery may result in poorer functional outcomes. The purpose of this study is to evaluate the impact of minimal proximal ulna malunion on elbow ROM and function at least one year after olecranon ORIF. METHOD A retrospective comparative cohort study took place in three level-1 trauma centers. Forty-nine adult volunteers who underwent ORIF for olecranon fracture were included. Patients were separated into two groups according to PUDA malreduction-defined as more than 5° of difference between the fractured and the contralateral elbow. OUTCOME MEASUREMENTS Radiographic ROM measurement, demographic data and quality of life questionnaires were recorded (PREE, MEPS, Q-DASH, SF12, VAS). RESULTS The mean follow up was 3 years and 9 months (1-7 years). There was no difference in terms of outcome, quality of reduction or range of motion between patients treated with plate or tension band. The mean PUDA on the fracture side was different from the normal side (2.20 vs 4.90, p<0.001). Fourteen patients (29%) had PUDA malunion. Those patients had decreased elbow flexion (-7°, p=0.011), extension (-11.2°, p=0.013) and total ROM (-18.6°, p=0.006) as opposed to the control group. Both groups had comparable quality of life questionnaire scores. Alcohol consumption was the only risk factor associated with worse scores. CONCLUSION Incidence of olecranon malunion-as defined by PUDA measurement - was 29% and it was associated with decreased elbow range of motion. Alcohol consumption was correlated with a worse prognosis in our series of patients. Tension band and plate fixation can maintain a good reduction in terms of PUDA and the choice of fixation method does not influence outcome. LEVEL OF EVIDENCE III Therapeutic study.

A Longitudinal Low Dose μCT Analysis of Bone Healing in Mice: A Pilot Study.

Low dose microcomputed tomography (μCT) is a recently matured technique that enables the study of longitudinal bone healing and the testing of experimental treatments for bone repair. This imaging technique has been used for studying craniofacial repair in mice but not in an orthopedic context. This is mainly due to the size of the defects (approximately 1.0 mm) in long bone, which heal rapidly and may thus negatively impact the assessment of the effectiveness of experimental treatments. We developed a longitudinal low dose μCT scan analysis method combined with a new image segmentation and extraction software using Hounsfield unit (HU) scores to quantitatively monitor bone healing in small femoral cortical defects in live mice. We were able to reproducibly quantify bone healing longitudinally over time with three observers. We used high speed intramedullary reaming to prolong healing in order to circumvent the rapid healing typical of small defects. Bone healing prolongation combined with μCT imaging to study small bone defects in live mice thus shows potential as a promising tool for future preclinical research on bone healing.

Braided tape is equivalent to modified Mason-Allen multi-strand #2 suture in subscapularis muscle repair: results of a biomechanical study

Background To help determine the optimal fixation method for subscapularis tendon repair in arthroplasty, the present study compares single-passage transosseous tape (BT) and modified Mason-Allen #2 suture (MA). Methods Eighteen human cadaveric shoulders were randomized to two repair constructs after arthroplasty preparation. Both techniques included two transosseous passages through the bicipital groove and then through the tendon at the level of the anatomical neck. Construct was tested using a traction machine, measuring cyclic loading and ultimate load to failure. Results The mean age of our specimens was 71 years. No significant difference was observed between the repair techniques in both mean ultimate load and cyclic loading. The mean (SD) ultimate load (UL) for BT was 293 (84) N and 342 (117) N for MA, which was not statistically significant (p = 0.374). The majority of repairs failed in the tendon. Bone cut-out was observed with the MA but not for the BT repair. No correlation was found between bone density and UL for BT (r = −0.09) but there was strong correlation for MA (r = 0.63). Conclusions The MA repair appears to be more dependant on bone mineral density for ultimate load, indicating that braided-tape might be better suited for osteoporotic patients to avoid bone cut-out.