Radial nerve injury following elbow external fixator: report of three cases and literature review

Radial neuropathy

Radial neuropathy is the third most common upper limb mononeuropathy after median and ulnar neuropathies. Muscle weakness, particularly wrist drop, is the main clinical feature of most cases of radial neuropathy, and an understanding of the radial nerve's anatomy generally makes localizing the lesion straightforward. Electrodiagnosis can help confirm a diagnosis of radial neuropathy and may help with more precise localization of the lesion. Nerve imaging with ultrasound or magnetic resonance neurography is increasingly used in diagnosis and is important in patients lacking a history of major arm or shoulder trauma. Radial neuropathy most often occurs in the setting of trauma, although many other uncommon causes have been described. With traumatic lesions, the prognosis for recovery is generally good, and for patients with persistent deficits, rehabilitation and surgical techniques may allow substantial functional improvement.

Measurement of the Radial Nerve Danger Zone in Filipino Adults: A Cadaveric Study

Introduction

The radial nerve danger zone (RNDZ) is an important anatomic consideration to anticipate or prevent injury in trauma assessment or surgical fixation. No published estimate currently exists for Filipinos. In this study, we sought to provide a local estimate and explore potential predictors of this anatomic region in Filipino adult cadavers.

Materials and methods

Posterior dissection to expose and measure the radial nerve, from the lateral epicondyle to the lateral intermuscular septum, was performed in 60 upper limbs from 30 formalin-preserved cadavers in the laboratory of the Department of Anatomy, College of Medicine, University of the Philippines Manila. Univariate and multivariate linear regression modelling was performed with RNDZ as the dependent variable and age, sex, height and humeral length as potential independent variables individually and in combinations.

Results

The mean radial nerve length from the lateral epicondyle to the lateral intermuscular septum was estimated at 10.6 cm (95% confidence interval: 10.3 cm, 10.9cm). Height and humeral length were statistically significant univariate predictors in female cadavers, while only height was significant in male cadavers. In addition, all multivariate regression models were statistically significant and accounted for more than 57% of the variability in female RNDZ estimates. In comparison, only models that included height and age were statistically significant predictors of RNDZ and accounted for at most 22% of the variability of the estimate in males.

Conclusion

The estimated length of the radial nerve danger zone generated in this study should be strongly considered over other published estimates in surgical fixation procedures performed in adult Filipinos.

Presentation and Management Outcome of High Radial Nerve Palsy with Tendon Transfers

Background

This randomized clinical trial was carried out to document the clinical presentation of isolated high radial nerve palsy (high RNP) and compare the outcome of triple tendon transfers.

Methods

The study included patients of all genders and ages who presented with isolated high RNP. Half of them were randomly assigned to the flexor carpi radialis set (FCR-set) of tendon transfers (group A) and a half to the flexor carpi ulnaris (FCU-set) of tendon transfers (group B).

Results

Out of 44 patients, 38 were males, and 6 were females. The age ranged from 7 years to 55 years. 26(59.09%) patients had primary RNP in association with fractures of the humerus. The postoperative mean disability of arm, shoulder, and hand score (Quick DASH-11 score) for the patients in the FCR-set of transfers was 34.54%% versus 41.81% for the FCU-set of transfers. 11 patients (25%) developed radial deviation deformity.

Conclusion

RNP was predominantly found among males of the young age group, and the majority of the cases resulted from preventable causes. The triple tendon transfers among patients of the two groups robustly restored the lost extension of the wrist and digits in a matching way. The patients also subjectively reported remarkable improvement in terms of the favorable Quick-DASH-11 scores. Radial deviation deformity occurred among half of the patients who underwent the FCU set of tendon transfers.

[External fixator of the elbow]

AIM OF SURGERY

The placement of an external elbow fixator can be statically carried out as temporary stabilization or as a hinged movement fixator. As a hinged movement fixator a functional follow-up treatment is possible due to control of the joint guidance and reduction of the compromising forces on the osteoligamentous structures.

INDICATIONS

As a temporary stabilization of the elbow, the external fixator is used as a damage control method. As a movement fixator it is used as an additional protection and movement control after complex osteoligamentous interventions and persisting tendency to dislocation of the joint and also as a standalone procedure. In some cases, the procedure is also used in distraction arthrolysis of stiff elbows and as a salvage procedure in patients with relevant comorbidities as part of fracture treatment.

CONTRAINDICATIONS

Inexperience in relation to the procedure as well as a local acute infection at the level of the intended pin locations should specifically be mentioned as contraindications. In addition, compliance and patient understanding of the procedure are essential for the success of treatment.

SURGICAL TECHNIQUE

Soft tissue preparation for pin placement should be preferred over percutaneous incisions to enable a safe bone exposure. Knowledge of the course of neurovascular structures (particularly the radial nerve) is essential. When placing a hinge, knowledge of the position and detection of the idealized center of rotation is of fundamental importance.

POSTOPERATIVE MANAGEMENT

The type of postoperative management required essentially depends on the underlying injury. When placing a hinged fixator, the aim is to enable movement as early as possible. Nevertheless, blocking of the hinged fixator may be useful for a short period of time. Adequate pin care over the duration of the treatment is essential in order to prevent complications.

RESULTS

Good functional results have been reported for the treatment of unstable elbows after primary and secondary placement of a hinged external fixator. Good functional scores and improvement in the range of motion were also recorded in the context of an arthrolysis (additive for open arthrolysis or distraction arthrolysis); however, in contrast a significant number of complications associated with this surgery are likely to emerge. As a definitive salvage procedure, satisfactory results were obtained in a small case series of a selected older patient group with relevant comorbidities.

The use of articulated external fixation for complex elbow trauma treatment

INTRODUCTION

We use external elbow joint fixator (FE-F4) for fracture and dislocation of the ulnohumeral joint to evaluate the early articular mobilization maintaining concentric reduction, protecting the osteoligamentous reconstruction and avoiding postoperative stiffness.

MATERIALS AND METHODS

Thirty-two patients (13 men and 19 women) were treated with FE-F4: 7 simple dislocations (21.9%), 15 distal humerus fractures (46.9%), 4 fractures and dislocations of which 1 terrible triad (12.5%), and 6 complex dislocations (18.7%). The mean age was 64 years. The average follow-up (FU) was 47 months. We evaluated the flexion-extension and prone-supination movement arc, VAS (Visual Analogue Scale), Quick DASH (Disability of the Arm, Shoulder and Hand score), MEPI (Mayo Elbow Performance Index) and the Broberg and Morrey rating system.

RESULTS

The average ROM was 125.9° for flexion-extension, 77.8° for pronation and 79.7° for supination. The average VAS was 0.56 at the FU, the MEPI score of 93.6, the Broberg and Morrey rating system of 92.4 and the Quick DASH of 8.7. No major complications were found after surgery, and no objective or subjective posterolateral or medial joint instability was found. No patients at the FU had a new surgery with arthromyolysis or elbow arthroplasty.

DISCUSSION

The elbow joint stiffness is the main cause of functional inability for the patient suffering from posttraumatic outcomes. The FE-F4 allows an early mobilization, even in case of injuries or complex reconstructions, keeping the joint stable and protecting any bone synthesis and the damaged capsule-ligament structures.

LEVELS OF EVIDENCE

IV.

CT Analysis of a Potential Safe Zone for Placing External Fixator Pins in the Humerus

BACKGROUND

Iatrogenic radial nerve injures are a common complication during the placement of external fixator pins at the lateral aspect of the humeral shaft. This study uses a three-dimensional measurement technique to locate a safe entry point for humeral pins when externally fixating the elbow. Methods: We fixed a guide wire to the radial nerve by a suture string, and used computed tomography (CT) to scan the upper limbs of cadaver specimens. Then, we measured the deviation angles of the radial nerve on the CT scans, and the distance from the radial nerve to the "elbow rotation center" (ERC). Result: The average distance from the radial nerve to the ERC was 87.3 ± 8.5 mm (range: 68-100 mm), 58.3 ± 11.3 mm (range: 32.12-82.84 mm), 106.3 ± 5.8 mm (range: 86.93-115.08 mm), and 113.9 ± 4.8 mm (range: 97.93-120.22 mm) at radial nerve deviation angles of 0°, -30°, 30°, and 45°, respectively. The average radial nerve deviation angle was -37.7° ± 7.7° and 123.9° ± 19.9° at 50 and 150 mm, respectively. Relative to 0°, the distance between the radial nerve and the ERC at radial nerve deviation angles of -30°, 30°, and 45° showed a significant difference (t = 18.20, p < 0.05; Z = 6.07, p < 0.001; Z = 6.40, p < 0.001, respectively). Conclusions: Pins inserted into the proximal humerus should be about 150 mm from the ERC with a radial nerve deviation angle of 30° anteriorly, and 50 mm from the ERC with a deviation angle of 30°-45° posteriorly.

High radial nerve palsy

High radial palsy is primarily associated with humeral shaft fractures, whether primary due to the initial trauma, or secondary to their treatment. The majority will spontaneously recover, therefore early surgical exploration is mainly indicated for open fractures or if ultrasonography shows severe nerve damage. Initial signs of nerve recovery may appear between 2 weeks and 6 months. Otherwise, the decision to explore the nerve is based on the patient's age, clinical examination and electroneuromyography, as well as ultrasonography findings. If recovery does not occur, an autograft is indicated only in younger patients, before 6 months, if local conditions are suitable. Otherwise, nerve transfers performed by an experienced team give satisfactory results and can be offered up to 10 months post-injury. Tendon transfers are the gold standard treatment and the only option available beyond 10 to 12 months. The results are reliable and fast.

Irreparable Radial Nerve Palsy Due to Delayed Diagnostic Management of a Giant Lipoma at the Proximal Forearm Resulting in a Triple Tendon Transfer Procedure: Case report and Brief Review of Literature

Background:

Non-traumatic radial nerve palsy (RNP) caused by local tumors is a rare and uncommon entity.

Methods:

A 62-year-old female presented with a left non-traumatic RNP, initially starting with weakness only. It was caused by a benign giant lipoma at the proximal forearm that was misdiagnosed over a period of 2 years. The slowly growth of the tumor led to an irreparable overstretching-related partial nerve disruption. For functional recovery of the patient, a triple tendon transfer procedure had to be performed.

Results:

Four months after surgery, the patient was completely able to perform her activities of daily living again. At the 10-months follow-up, strength of wrist extension, thumb's extension and abduction, and long fingers II-V extension had all improved to grade 4 in Medical Research Council scale (0-5). In order to restore motion, the patient reported that she would undergo the same triple tendon transfer procedure a second time where necessary. Due to the initially misdiagnosed tumor, there was an overall delayed duration of time for functional recovery of the patient.

Conclusion:

The triple tendon transfer procedure offers a useful and reliable method to restore functionality for patients sustaining irreparable RNP. However, it must be noted critically with our patient that this procedure probably would have been avoided. Initially, there was weakness only by entrapment of the radial nerve. RNP caused by local tumors are uncommon but known from the literature, and so it should be considered generally in differential diagnosis of non-traumatic RNP.