Quantifying regeneration in patients following peripheral nerve injury.

Healthy nerve function provides humans with the control of movement; sensation (such as pain, touch and temperature) and the quality of skin, hair and nails. Injury to this complex system creates a deficit in function, which is slow to recover, and rarely, if ever, returns to what patients consider to be normal. Despite promising results in pre-clinical animal experimentation effective translation is challenged by a current inability to quantify nerve regeneration in human subjects and relate this to measurable and responsible clinical outcomes. In animal models, muscle and nerve tissue samples can be harvested following experimental intervention. This allows direct quantification of muscle mass and quality and quantity of regeneration of axons; such an approach is not applicable in human medicine as it would ensure a significant functional deficit. Nevertheless a greater understanding of this process would allow the relationship that exists between neural and neuromuscular regeneration and functional outcome to be more clearly understood. This article presents a combined commentary of current practice from a specialist clinical unit and research team with regard to laboratory and clinical quantification of nerve regeneration. We highlight how electrophysiological diagnostic methods (which are used with significant recognised limitations in the assessment of clinical medicine) can potentially be used with more validity to interpret and assess the processes of neural regeneration in the clinical context, thus throwing light on the factors at play in translating lab advances into the clinic.

An assessment of fatigability following nerve transfer to reinnervate elbow flexor muscles.

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.

A quantitative assessment of the functional recovery of flexion of the elbow after nerve transfer in patients with a brachial plexus injury.

AIMS: Improvements in the evaluation of outcome after nerve transfers are required. The assessment of force using the Medical Research Council (MRC) grades (0 to 5) is not suitable for this purpose. A ceiling effect is encountered within MRC grade 4/5 rendering this tool insensitive. Our aim was to show how the strength of flexion of the elbow could be assessed in patients who have undergone a re-innervation procedure using a continuous measurement scale. METHODS: A total of 26 patients, 23 men and three women, with a mean age of 37.3 years (16 to 66), at the time of presentation, attended for review from a cohort of 52 patients who had undergone surgery to restore flexion of the elbow after a brachial plexus injury and were included in this retrospective study. The mean follow-up after nerve transfer was 56 months (28 to 101, standard deviation (sd) 20.79). The strength of flexion of the elbow was measured in a standard outpatient environment with a static dynamometer. RESULTS: In total, 21 patients (81%) gained MRC grade 4 strength of flexion of the elbow. The mean force of flexion was 7.2 kgf (3 to 15.5, sd 3.3). CONCLUSION: This study establishes that the dynamometer may be used for assessing the strength of flexion of the elbow in the outpatient department after nerve reconstructive surgery. Cite this article: Bone Joint J 2016;98-B:1517-20.

Nerve injuries associated with supracondylar fractures of the humerus in children: our experience in a specialist peripheral nerve injury unit.

AIMS: We aimed to identify the pattern of nerve injury associated with paediatric supracondylar fractures of the humerus. PATIENTS AND METHODS: Over a 17 year period, between 1996 and 2012, 166 children were referred to our specialist peripheral nerve injury unit. From examination of the medical records and radiographs were recorded the nature of the fracture, associated vascular and neurological injury, treatment provided and clinical course. RESULTS: Of the 166 patients (111 male, 55 female; mean age at time of injury was seven years (standard deviation 2.2)), 26 (15.7%) had neurological dysfunction in two or more nerves. The injury pattern in the 196 affected nerves showed that the most commonly affected nerve was the ulnar nerve (43.4%), followed by the median (36.7%) and radial (19.9%) nerves. A non-degenerative injury was seen in 27.5%, whilst 67.9% were degenerative in nature. Surgical exploration of the nerves was undertaken in 94 (56.6%) children. The mean follow-up time was 12.8 months and 156 (94%) patients had an excellent or good clinical outcome according to the grading of Birch, Bonney and Parry. CONCLUSION: Following paediatric supracondylar fractures we recommend prompt referral to a specialist unit in the presence of complete nerve palsy, a positive Tinel's sign, neuropathic pain or vascular compromise, for consideration of nerve exploration. TAKE HOME MESSAGE: When managed appropriately, nerve recovery and clinical outcomes for this paediatric population are extremely favourable. Cite this article: Bone Joint J 2016;98-B:851-6.

Pediatric fractures and dislocations of the hip and pelvis.

Recognition of an unstable pelvic fracture or a significant hip injury in children is important. Clinical assessment plays a valuable role as does the judicious use of imaging modalities in determining the most effective form of treatment, but the routine use of the standard AP pelvic radiograph is questioned. The concept of age and skeletal maturity has been re-evaluated, allowing the appropriate identification of cases that would benefit from an aggressive operative approach. A dual-tier approach to the treatment of pediatric pelvic trauma is suggested with an appreciation that there is no substantial evidence base for the surgical treatment of most injuries. Displaced femoral neck fractures and injuries to the hip joint that damage the articular or physeal cartilages require careful assessment and prompt and careful reduction and stabilization.

Differences in the Composition of Adhesive and Non-Adhesive Mucus From the Limpet Lottia limatula.

The mucus used by the limpet Lottia limatula to form glue-like attachments was compared biochemically to the slippery mucus produced during other activities, such as suction adhesion. Colorimetric assays revealed the protein content of the adhesive mucus to be 2.1 times greater than that of the non-adhesive form, and the carbohydrate content to be 1.9 times greater. Both forms of mucus contained roughly six times as much protein as carbohydrate, and there was no difference in their inorganic elemental compositions. Quantitative analysis of the protein content by SDS-PAGE and a scanning densitometer revealed a similar protein composition in both forms of mucus; but three notable differences emerged. First, the overall difference in protein concentration was confirmed. In addition, there was a 118 kD protein that was common only in the adhesive mucus, and a 68 kD protein that occurred only in the non-adhesive mucus.