Aims. This study aimed to use intraoperative free electromyography to examine how the placement of a retractor at different positions along the anterior acetabular wall may affect the femoral nerve during total hip arthroplasty (THA) when undertaken using the direct anterior approach (THA-DAA). Methods. Intraoperative free electromyography was performed during primary THA-DAA in 82 patients (94 hips). The highest position of the anterior acetabular wall was defined as the “12 o’clock” position (middle position) when the patient was in supine position. After exposure of the acetabulum, a retractor was sequentially placed at the ten, 11, 12, one, and two o’clock positions (right hip; from superior to inferior positions). Action potentials in the femoral nerve were monitored with each placement, and the incidence of positive reactions (defined as explosive, frequent, or continuous action potentials, indicating that the nerve was being compressed) were recorded as the primary outcome. Secondary outcomes included the incidence of positive reactions caused by removing the femoral head, and by placing a retractor during femoral exposure; and the incidence of femoral nerve palsy, as detected using manual testing of the strength of the quadriceps muscle. Results. Positive reactions were significantly less frequent when the retractor was placed at the ten (15/94; 16.0%), 11 (12/94; 12.8%), or 12 o’clock positions (19/94; 20.2%), than at the one (37/94; 39.4%) or two o’clock positions (39/94; 41.5%) (p < 0.050). Positive reactions also occurred when the femoral head was removed (28/94; 29.8%), and when a retractor was placed around the proximal femur (34/94; 36.2%) or medial femur (27/94; 28.7%) during femoral exposure. After surgery, no patient had reduced strength in the quadriceps muscle. Conclusion. Placing the anterior acetabular retractor at the one or two o’clock positions (right hip; inferior positions) during THA-DAA can increase the rate of electromyographic signal changes in the femoral nerve. Thus, placing a retractor in these positions may increased the risk of the development of a femoral nerve palsy. Cite this article: Bone Joint J 2022;104-B(2):193–199

1. Telemetering electromyography has been used to investigate the pattern of activity of certain muscles of the lower limb and back while the subjects walked up and down stairs. 2. During walking up and down stairs each limb has a supporting and swinging phase in each complete step. 3. Walking up stairs revealed the following facts. Firstly, raising the body on to the stair above is brought about by the contraction of the soleus, quadriceps femoris, hamstrings and gluteus maximus; the gluteus medius at the same time prevents the body falling on to the unsupported side. Secondly, the tibialis anterior dorsiflexes the foot during the swinging phase and helps the limb to clear the stair on which the supporting limb is placed. Thirdly, the hamstrings flex the leg at the knee in the early part of the swinging phase and control the terminal part of extension at the knee at the end of this phase. Fourthly, both erectores spinae contract twice in each step and control the forward bending of the body at the vertebral column. 4. Walking down stairs revealed the following. Firstly, the body is lowered on to the stair below by the controlled lengthening of the soleus and quadriceps femoris; the gluteus medius at the same time prevents the body from falling on to the unsupported side. Secondly, the tibialis anterior inverts the foot at the beginning of the supporting phase as the toe is placed on the stair below and dorsiflexes the foot in the middle of the swinging phase. Thirdly, the hamstrings control the extension of the leg at the knee during the middle of the swinging phase. Fourthly, both erectores spinae contract twice in each step and prevent forward bending of the trunk at the vertebral column

1. The deep posterior muscles of the neck are innervated by the posterior branches of spinal nerves, which branch off immediately after the root emerges from the intervertebral foramen. Electromyographic examination of these muscles permits a differential diagnosis to be made between intraforaminal and extraforaminal brachial plexus lesions.

2. The earlier diagnosis and prognosis thus achieved permit definitive treatment, in particular suture of the torn nerve trunks in recent extraforaminal cases.

We investigated the predictive value of intra-operative neurophysiological investigations in obstetric brachial plexus injuries. Between January 2005 and June 2011 a total of 32 infants of 206 referred to our unit underwent exploration of the plexus, including neurolysis. The findings from intra-operative electromyography, sensory evoked potentials across the lesion and gross muscular response to stimulation were evaluated. A total of 22 infants underwent neurolysis alone and ten had microsurgical reconstruction. Of the former, one was lost to follow-up, one had glenoplasty and three had subsequent nerve reconstructions. Of the remaining 17 infants with neurolysis, 13 (76%) achieved a modified Mallet score > 13 at a mean age of 3.5 years (0.75 to 6.25). Subluxation or dislocation of the shoulder is a major confounding factor. The positive predictive value and sensitivity of the intra-operative EMG for C5 were 100% and 85.7%, respectively, in infants without concurrent shoulder pathology. The positive and negative predictive values, sensitivity and specificity of the three investigations combined were 77%, 100%, 100% and 57%, respectively. In all, 20 infants underwent neurolysis alone for C6 and three had reconstruction. All of the former and one of the latter achieved biceps function of Raimondi grade 5. The positive and negative predictive values, sensitivity and specificity of electromyography for C6 were 65%, 71%, 87% and 42%, respectively. Our method is effective in evaluating the prognosis of C5 lesion. Neurolysis is preferred for C6 lesions. Cite this article: Bone Joint J 2013;95-B:699–705

Aims. Improvements in the evaluation of outcomes following peripheral nerve injury are needed. Recent studies have identified muscle fatigue as an inevitable consequence of muscle reinnervation. This study aimed to quantify and characterize muscle fatigue within a standardized surgical model of muscle reinnervation. Patients and Methods. This retrospective cohort study included 12 patients who underwent Oberlin nerve transfer in an attempt to restore flexion of the elbow following brachial plexus injury. There were ten men and two women with a mean age of 45.5 years (27 to 69). The mean follow-up was 58 months (28 to 100). Repeated and sustained isometric contractions of the elbow flexors were used to assess fatigability of reinnervated muscle. The strength of elbow flexion was measured using a static dynamometer (KgF) and surface electromyography (sEMG). Recordings were used to quantify and characterize fatigability of the reinnervated elbow flexor muscles compared with the uninjured contralateral side. Results. The mean peak force of elbow flexion was 7.88 KgF (. sd. 3.80) compared with 20.65 KgF (. sd . 6.88) on the contralateral side (p < 0.001). Reinnervated elbow flexor muscles (biceps brachialis) showed sEMG evidence of fatigue earlier than normal controls with sustained (60-second) isometric contraction. Reinnervated elbow flexor muscles also showed a trend towards a faster twitch muscle fibre type. Conclusion. The assessment of motor outcomes must involve more than peak force alone. Reinnervated muscle shows a shift towards fast twitch fibres following reinnervation with an earlier onset of fatigue. Our findings suggest that fatigue is a clinically relevant characteristic of reinnervated muscle. Adoption of these metrics into clinical practice and the assessment of outcome could allow a more meaningful comparison to be made between differing forms of treatment and encourage advances in the management of motor recovery following nerve transfer. Cite this article: Bone Joint J 2019;101-B:867–871

Peripheral nerve injury is an uncommon but serious complication of hip surgery that can adversely affect the outcome. Several studies have described the use of electromyography and intra-operative sensory evoked potentials for early warning of nerve injury. We assessed the results of multimodal intra-operative monitoring during complex hip surgery. We retrospectively analysed data collected between 2001 and 2010 from 69 patients who underwent complex hip surgery by a single surgeon using multimodal intra-operative monitoring from a total pool of 7894 patients who underwent hip surgery during this period. In 24 (35%) procedures the surgeon was alerted to a possible lesion to the sciatic and/or femoral nerve. Alerts were observed most frequently during peri-acetabular osteotomy. The surgeon adapted his approach based on interpretation of the neurophysiological changes. From 69 monitored surgical procedures, there was only one true positive case of post-operative nerve injury. There were no false positives or false negatives, and the remaining 68 cases were all true negative. The sensitivity for predicting post-operative nerve injury was 100% and the specificity 100%. We conclude that it is possible and appropriate to use this method during complex hip surgery and it is effective for alerting the surgeon to the possibility of nerve injury

Aims. Our aim was to describe the atypical pattern of increased fatty degeneration in the infraspinatus muscle compared with the supraspinatus in patients with a massive rotator cuff tear. We also wished to describe the nerve conduction and electromyography findings in these patients. Patients and Methods. A cohort of patients undergoing surgery for a massive rotator cuff tear was identified and their clinical records obtained. Their MRI images were reviewed to ascertain the degree of retraction of the torn infraspinatus and supraspinatus muscles, and the degree of fatty degeneration in both muscles was recorded. Nerve conduction studies were also performed in those patients who showed more degeneration in the infraspinatus than in the supraspinatus. Results. Out of a total of 396 patients who underwent surgery for a massive rotator cuff tear between 2006 and 2015, 35 who had more severe fatty degeneration in the infraspinatus than in the supraspinatus were identified. There were 13 men and 22 women. Their mean age was 67.2 years (56 to 81). A total of 20 (57%) had grade 4 fatty degeneration as classified by Fuchs et al, in the infraspinatus. Patte grade 3 muscle retraction was seen in 25 patients (71%). In all, eight patients (23%) had abnormal nerve conduction studies. The mean retraction of the infraspinatus was 3.6 cm (2.1 to 4.8) in patients with more severe fatty degeneration in the infraspinatus, versus 3.0 cm (1.7 to 5.5) in those with more severe degeneration in the supraspinatus (p = 0.003). The retraction ratios were 0.98 (0.61 to 1.57) and 0.77 (0.38 to 1.92), respectively (p < 0.001). Conclusion. Fatty degeneration affecting the infraspinatus more than the supraspinatus may be, in the context of a massive rotator cuff tear, due to entrapment of the suprascapular nerve at the spinoglenoid notch. Cite this article: Bone Joint J 2016;98-B:1505–9

We investigated the detailed anatomy of the gluteus maximus, gluteus medius and gluteus minimus and their neurovascular supply in 22 hips in 11 embalmed adult Caucasian human cadavers. This led to the development of a surgical technique for an extended posterior approach to the hip and pelvis that exposes the supra-acetabular ilium and preserves the glutei during revision hip surgery. Proximal to distal mobilisation of the gluteus medius from the posterior gluteal line permits exposure and mobilisation of the superior gluteal neurovascular bundle between the sciatic notch and the entrance to the gluteus medius, enabling a wider exposure of the supra-acetabular ilium. This technique was subsequently used in nine patients undergoing revision total hip replacement involving the reconstruction of nine Paprosky 3B acetabular defects, five of which had pelvic discontinuity. Intra-operative electromyography showed that the innervation of the gluteal muscles was not affected by surgery. Clinical follow-up demonstrated good hip abduction function in all patients. These results were compared with those of a matched cohort treated through a Kocher–Langenbeck approach. Our modified approach maximises the exposure of the ilium above the sciatic notch while protecting the gluteal muscles and their neurovascular bundle. Cite this article: Bone Joint J 2014;96-B:48–53

Aims

Conventional patient-reported surveys, used for patients undergoing total hip arthroplasty (THA), are limited by subjectivity and recall bias. Objective functional evaluation, such as gait analysis, to delineate a patient’s functional capacity and customize surgical interventions, may address these shortcomings. This systematic review endeavours to investigate the application of objective functional assessments in appraising individuals undergoing THA.

In a 41-year-old man, right-sided infraspinatus muscle weakness was associated with compression of the suprascapular nerve caused by a spinoglenoid ganglion cyst. The lesion was confirmed using electromyography and MRI. In addition, arthroscopy showed an incomplete discoid labrum. The free inner edge of the labrum was removed as in a meniscectomy of a discoid meniscus in the knee joint. Arthroscopic decompression of the cyst was performed through a juxtaglenoid capsulotomy which was left open. Neurological function recovered completely

Aims

Children with spinal dysraphism can develop various musculoskeletal deformities, necessitating a range of orthopaedic interventions, causing significant morbidity, and making considerable demands on resources. This systematic review aimed to identify what outcome measures have been reported in the literature for children with spinal dysraphism who undergo orthopaedic interventions involving the lower limbs.

Aims

The aim of this study was to reassess the rate of neurological, psoas-related, and abdominal complications associated with L4-L5 lateral lumbar interbody fusion (LLIF) undertaken using a standardized preoperative assessment and surgical technique.

Injury to the sciatic nerve is one of the more serious complications of acetabular fracture and traumatic dislocation of the hip, both in the short and long term. We have reviewed prospectively patients, treated in our unit, for acetabular fractures who had concomitant injury to the sciatic nerve, with the aim of predicting the functional outcome after these injuries. Of 136 patients who underwent stabilisation of acetabular fractures, there were 27 (19.9%) with neurological injury. At initial presentation, 13 patients had a complete foot-drop, ten had weakness of the foot and four had burning pain and altered sensation over the dorsum of the foot. Serial electromyography (EMG) studies were performed and the degree of functional recovery was monitored using the grading system of the Medical Research Council. In nine patients with a foot-drop, there was evidence of a proximal acetabular (sciatic) and a distal knee (neck of fibula) nerve lesion, the double-crush syndrome. At the final follow-up, clinical examination and EMG studies showed full recovery in five of the ten patients with initial muscle weakness, and complete resolution in all four patients with sensory symptoms (burning pain and hyperaesthesia). There was improvement of functional capacity (motor and sensory) in two patients who presented initially with complete foot-drop. In the remaining 11 with foot-drop at presentation, including all nine with the double-crush lesion, there was no improvement in function at a mean follow-up of 4.3 years

Aims

The aim of this study was to review the current evidence surrounding curve type and morphology on curve progression risk in adolescent idiopathic scoliosis (AIS).

1. A case of ulnar nerve compression at the wrist caused by rheumatoid arthritis producing motor and sensory changes is presented. 2. The diagnosis from compression at the elbow can be determined by electromyography. 3. It may be that lesions of the deep branch leading to motor changes only occur in rheumatoid arthritis more often than is suspected, their effects being hidden by the concomitant disease and its associated muscle wasting

1. In ten healthy young men an experimental paralysis of the supraspinatus muscle was induced with the aid of Xylocaine injected in or near the suprascapular nerve. 2. The completeness of the paralysis was checked by electromyography. 3. With the supraspinatus muscle completely eliminated, all subjects could move the arm against gravity through its full range in the shoulder joint, though the force and the power of endurance during abduction were diminished. 4. It is concluded that the role of the supraspinatus muscle is of a quantitative nature only

The role of muscle function in the aetiology of recurrent dislocation of the patella has been examined. Eleven of the 12 patients we studied had joint hypermobility. Muscle biopsies from eight of nine patients treated by surgery had a predominance of abnormal Type 2C fibres, and three of six patients whose quadriceps muscles were studied by electromyography also had abnormal results. Our preliminary findings suggest that there may be a primary muscular defect in many cases of recurrent dislocation of the patella