RESUMEN
Although reverse shoulder arthroplasty (RSA) has shown successful postoperative outcomes, little is known about compensatory activation patterns of remaining shoulder muscles following RSA. The purpose of this experimental case control series was to investigate shoulder muscle strength and neuromuscular activation of deltoid and teres minor muscles 2 years after RSA. Humerus lengthening, center-of-rotation medialization, maximal voluntary strength, and electromyographic (EMG) activity were compared between the operated and the non-operated side of 13 patients (mean age: 73 years). Shoulder muscle strength was significantly lower on the operated side for external rotation (-54%), internal rotation (-20%), and adduction (-13%). Agonist deltoid EMG activity was lower on the operated side for shoulder flexion, extension, and internal and external rotation (p < 0.05). Antagonist deltoid coactivation was higher on the operated side for external rotation (p < 0.001). Large correlation coefficients were observed between shoulder adductor strength asymmetry and both center-of-rotation medialization (r = -0.73) and humerus lengthening (r = 0.71). Shoulder abduction strength and neuromuscular activation were well preserved 2 years after RSA, while persistent strength and activation deficits were observed for shoulder adduction and internal and external rotation. Additional studies are required to elucidate shoulder neuromuscular activation patterns before and after RSA to support decision making for surgical, implant design, and rehabilitation choices.
RESUMEN
INTRODUCTION: Upper limb physeal injuries are dealt with differently simply because they do not hinder with the functional abilities of an individual. Humerus lengthening was first attempted in 1978 after which it encouraged many surgeons to safely perform the procedure. Radial nerve palsy occurring as a complication of humeral lengthening was a major concern. CASE REPORT: We report a case of a 17-year-old girl with physeal arrest at the proximal physis of the humerus with etiology of post-trauma/post-infection. She presented with a shortening of 8 cm and restricted shoulder movements. We performed a lengthening of the humerus based on the principle of distraction osteogenesis. We used the paediatric limb reconstruction system to distract the corticotomy. However, postoperatively, she developed radial nerve palsy, despite our intraoperative precautionary measures. Distraction was started at 1mm/day. She then showed the progress of radial nerve recovery and full recovery was noted by 5 months post-operatively. The length of the distraction compression assembly had to be changed twice to longer sizes to accommodate the required amount of lengthening. After consolidation of regenerate was confirmed with serial radiographs, external fixator was removed. She was then maintained on a functional brace. We were able to achieve 8cm of lengthening following distraction, and the cosmetic appearance of the patient improved to the patient's and attenders' satisfaction. CONCLUSION: Humeral lengthening can safely be performed. Careful insertion of the distal pins and performance of the corticotomy will ensure the safety of the radial nerve. Even if radial nerve palsy occurs after all precautions are taken, recovery can be expected.
RESUMEN
BACKGROUND: The main mechanical effect after reverse shoulder arthroplasty (RSA) is the lowering of the glenohumeral rotation center. The optimal value of the humeral lowering after RSA is still debated. The main objective of our study was to determine the lowering and medialization of the humerus and to correlate these parameters with short-term functional results. MATERIALS AND METHODS: The study included 70 patients with complete radiographic and clinical data. A multivariate analysis was used to compare the clinical and radiographic outcomes with the humeral lowering. RESULTS: The mean humeral lowering was 25.4 mm (range, 6-38 mm), and the mean medialization was 9.2 mm (range, 0-20 mm). Humeral lowering significantly influenced active forward elevation and the rate of scapular notching. DISCUSSION: The best clinical results and the lowest incidence of scapular notching were found after a lowering of more than 24 mm in our series. We recommend humeral lengthening of at least 24 mm after implanting a total reverse shoulder prosthesis.
Asunto(s)
Artroplastía de Reemplazo de Hombro/métodos , Húmero/diagnóstico por imagen , Húmero/cirugía , Articulación del Hombro/diagnóstico por imagen , Articulación del Hombro/cirugía , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Rotación , Lesiones del Manguito de los Rotadores/cirugía , Escápula/diagnóstico por imagenRESUMEN
Distraction osteogenesis of the humerus with fully implantable lengthening is now possible since the diameter of the available nails was reduced to 10 mm and below. We report on the first intramedullary lengthening cases of the humerus with two different lengthening devices (FITBONE and PRECICE). Two different approaches and implantation techniques were used. We retrospectively reviewed clinical and radiographic data and pointed out results, pitfalls and complications of the procedure. Four adult patients with relevant length discrepancy of the humerus were treated with fully implantable systems in two centers between 2012 and 2015. Three patients were treated with FITBONE by an antegrade approach; one patient had lengthening with a PRECICE and a retrograde approach. Average nail lengthening was 55 mm (40-65 mm), and the average duration of lengthening was 70 days (52-95 days). The average distraction index was 0.72 mm/day (range 0.4-1.0 mm/day) or 12.5 days/cm (range 8.0-16.2 days/cm). The average consolidation index was 33.6 days/cm (range 25-45 days/cm). There was an implant failure (arrest) with the PRECICE. After consolidation and exchange with a technically improved implant, the course of treatment was uneventful. In patients with antegrade lengthening shoulder abduction decreased, and in the patient with the retrograde approach it improved but elbow extension decreased marginally. Reduced motion of the adjacent joints can be a major problem in intramedullary lengthening of the humerus. This first case series in the field of a rare indication suggests that lengthening of the humerus by fully implantable lengthening nails might be a valuable alternative to lengthening with external fixation. Main advantage of the PRECICE technology is the possible shortening in-between of lengthening.