Transfer of axillary nerve branches to reconstruct elbow extension in tetraplegics: a laboratory investigation of surgical feasibility

In spinal cord injuries at the C6 level, elbow extension is lost and needs reconstruction. Traditionally, elbow extension has been reconstructed by muscle transfers, which improve function only moderately. We have hypothesized that outcomes could be ameliorated by nerve transfers rather than muscle transfers. We anatomically investigated nerve branches to the teres minor and posterior deltoid as donors for transfer to triceps motor branches. In eight formalin-fixed cadavers, the axillary nerve, the teres minor branch, the posterior deltoid branch, the triceps long and upper medial head motor branches, and the thoracodorsal nerve were dissected bilaterally, their diameters measured and their myelinated fibers counted. To simulate surgery, using an axillary approach in two fresh cadavers, we transferred the teres minor or the posterior deltoid branch to the triceps long head and to the thoracodorsal nerve. The posterior division of the axillary nerve gave off the teres minor motor branch and then the branch to the posterior deltoid, terminating as the superior lateral brachial cutaneous nerve. The diameters of the teres minor motor branch, posterior deltoid, triceps long and upper medial head branches, and the thoracodorsal nerve all were ～2 mm, with minimal variation. The nerves varied little in their numbers of myelinated fibers, being consistently about 1,000. Via an axillary approach, either the teres minor or the posterior deltoid branch could be transferred directly to the thoracodorsal nerve or to triceps branches without any tension.     

Applied anatomy of the axillary nerve for selective neurotization of the deltoid muscle

Morphologic and internal topographic features of the axillary nerve were studied in 40 cadaveric shoulders to provide anatomic data for selective neurotization of the deltoid muscle in axillary nerve injury. The axillary nerve can be divided into three segments. Proximal to the subscapularis muscle, the axillary nerve is a single nerve trunk. Nerve fascicles to the deltoid muscle are identified at its lateral part. In front of the subscapularis muscle, the axillary nerve forms into the lateral and medial fasciculi groups. Distal to the subscapularis muscle, the nerve divides into anterior and posterior branches, which are continuations of the lateral and medial fasciculi groups, respectively. The anterior branch contains all fibers that innervate to the anterior and middle deltoid muscle. In 90% of cases, the posterior branch contains part or all nerve fibers to the posterior deltoid muscle. Nerve fibers to the teres minor and cutaneous sensory fibers are found in the posterior branch. In neurotization of the deltoid muscle, the best approach is to match the donor nerve to the lateral fasciculi group, which will give the highest percentage of reinnervation of the deltoid muscle.     

The posterior deltoid to triceps transfer: a clinical and biomechanical assessment

Transfer of the posterior deltoid muscle to the triceps insertion for elbow extension provides improved function in patients with C5 and C6 level tetraplegia. We have modified the surgical technique using the tibialis anterior tendon as a graft. The length-tension characteristics and available amplitude of the posterior deltoid muscle were determined with intraoperative electrical stimulation. The excursion of the posterior deltoid muscle was 7.31 cm with a standard deviation of 1.23 cm. Postoperative mean torque measurements of elbow extension power were 36.4 kg cm with a standard deviation of 15 kg cm. All patients had maximal strength between 90 degrees and 120 degrees of elbow flexion. Length-tension curves for the posterior deltoid muscle showed a large range of effective strength and helped confirm optimum tension of the posterior deltoid muscle and proper shoulder and elbow positions at surgery. Clinical results in 10 patients were excellent.     

The fibrous frame of the deltoid muscle. Its functional and surgical relevance

Black lines seen on magnetic resonance imaging in the middle part of the deltoid suggest the presence of fibrous bands. Anatomic study of 30 deltoid muscles was done. Eight half-cone shaped distal fibrous structures merged together into the distal tendon of the deltoid muscle. The middle part of the deltoid muscle contains four deep fibrous bands that glide inside the distal half-cones. The anterior and posterior parts of the deltoid muscle lacked such bands. Histologic study confirmed the presence of the bands and cones. In the middle part of the deltoid, muscle fibers are oblique between the bands or between the bands and the half-cones. This multipennate structure favors strength instead of range of excursion of the muscle. Because of its significant change of direction around the humeral head, at the onset of elevation of the arm, the deltoid muscle sustains forces that press the muscle against the head which then leads to deformation of the muscle. The fibrous bands make the muscle strong enough to support these forces. The middle part of the muscle is of greatest importance in comparison with the other parts. This should be considered during shoulder rehabilitation. The presence of the fibrous band originating from the anterior corner of the acromion may help create a strong repair after splitting the deltoid.     

The posterior subdeltoid approach: a modified access to the posterior glenohumeral joint.

A modified surgical approach to the posterior aspect of the glenohumeral joint and/or the dorsal glenoid is described. This access does not alter any muscle insertion or neuromuscular planes. After the skin incision is made, the inferior border of the spinal part of the deltoid is identified and the deltoid muscle is mobilized and retracted, thus offering an excellent approach to the interval between the infraspinatus and teres minor muscles. This interval is split parallel to the muscle fibers. This surgical approach was first established in 10 cadaverous shoulders and then performed in 12 patients with posterior shoulder pathology. In the cadaver study, the closest distance to the axillary nerve with this approach was 22 mm. In all 12 cases, the surgical procedure could be performed without any problems.     

Shoulder electromyography in multidirectional instability

We studied shoulder muscle activity in multidirectional instability (MDI) and multidirectional laxity (MDL) of the shoulder, our hypothesis being that altered muscle activity plays a role in their pathogenesis. Six muscles (supraspinatus, infraspinatus, subscapularis, anterior deltoid, middle deltoid, and posterior deltoid) were investigated by use of intramuscular dual fine-wire electrodes in 7 normal shoulders, 5 MDL shoulders, and 6 MDI shoulders. Each subject performed 5 types of exercise (rotation in neutral, 45 degrees of abduction, 90 degrees of abduction, flexion/extension, and abduction/adduction) on an isokinetic muscle dynamometer at two rates, 90 degrees /s and 180 degrees /s. After filtering, rectification, and smoothing, the electromyography signal was normalized by using the peak voltage of the movement cycle. In subjects with MDI, compared with normal subjects, activity patterns of the anterior deltoid were different during rotation in neutral and 90 degrees of abduction, whereas those of the middle and posterior deltoid were different during rotation in 90 degrees of abduction. In subjects with MDL, the posterior deltoid showed increased activity compared with normal subjects during adduction. Activity patterns of the supraspinatus, infraspinatus, and subscapularis appeared similar in both groups. Dual fine-wire electromyography offers insight into the complex role of shoulder girdle muscle function in normal movement and in instability. Altered patterns of shoulder girdle muscle activity and imbalances in muscle forces support the theory that impaired coordination of shoulder girdle muscle activity and inefficiency of the dynamic stabilizers of the glenohumeral joint are involved in the etiology of MDI. Interestingly, the abnormalities are in the deltoid rather than the muscles of the rotator cuff.     

Posterolateral approach of the shoulder: assessment of 50 cases

A new posterior approach of the shoulder for hemiarthroplasty or total arthroplasty has been used 53 times over a 6-year period. The posterior part of the deltoid is detached subperiosteally from the spine and the posterior aspect of the acromion. Distally, the incision is made between the posterior and middle parts of the muscle. The subacromial bursa is opened to reveal the plane of the external rotator muscles. The articular approach is performed by means of an osteotomy of the external rotator muscles' insertion. This approach provides a wide exposure of the joint. The socket can be seen almost head-on, which eases glenoid preparation during arthroplasty. Transosseous reinsertion of the osteotomy fragments seems stronger that tendinous suture. One early case of failure of external rotator muscle repair was recorded. Atrophy of the posterior deltoid was found in 2 cases.     

The anatomic branch pattern of the axillary nerve

The purpose of this study is to determine the surgical anatomy and innervation pattern of the branches of the axillary nerve and discuss the clinical importance of the presented findings. We dissected 30 shoulders in 15 fixed adult cadavers under a microscope through anterior and posterior approaches. The axillary nerve was examined in 2 segments in relation to the underlying subscapularis muscle. The axillary nerve gave off no branches in the first segment in 85% of cases. When the posterior approach was used, the axillary nerve and its branches were observed to be in a triangular-shaped area. The mean distance from the posterolateral corner of the acromion to the axillary nerve and its branches was 7.8 cm. In all cases, the posterior branch of the axillary nerve gave off its first muscular branch to innervate the teres minor. The joint branch of the axillary nerve was observed to branch out in 3 different patterns. The acromial and clavicular parts of the deltoid muscle were observed to be innervated from the anterior branch of the axillary nerve in all cases. The posterior part of the deltoid muscle was observed to be innervated in 3 different patterns. The posterior part of the deltoid was innervated from the branch or branches coming only from the posterior branch in 70% of cases, from the anterior and posterior branches in 26.7% of cases, and from the anterior branch in 3.3% of cases. The findings of this study are useful for identifying each of the branches of the axillary nerve and have implications for surgeries related with selective innervation.     

Quantitative evaluation of the posterior deltoid to triceps tendon transfer based on muscle architectural properties

The architectural properties of the posterior deltoid muscle and the 3 heads of the triceps were measured using microdissection techniques to determine whether substitution of triceps function by the posterior deltoid is architecturally appropriate. Muscles from 10 fresh cadaver specimens were fixed by high-pressure perfusion using buffered formaldehyde. Muscle architectural properties, including pennation angle, fiber bundle length, sarcomere length, and physiologic cross-sectional area, were determined. Fiber bundle length varied significantly among the deltoid (123.1 +/- 7.8 mm), medial (64.5 +/- 3.8 mm), lateral (66.5 +/- 5.4 mm), and long (85.3 +/- 9.5) heads of the triceps. The physiologic cross-sectional area of the posterior deltoid was significantly less than the total triceps area and was predicted to provide only approximately 20% of the maximum isometric tension of the combined triceps heads. These data demonstrate that the long fibers of the posterior deltoid render it a very suitable transfer to provide elbow extension because of its tremendous excursion and also show why useful functional results seem relatively independent of posterior deltoid tension at the time of surgery.     

Fibrous deltoid muscle in Vietnamese children

To evaluate the clinical and functional results of surgical treatment for fibrous deltoid muscle in children, a retrospective study has been undertaken. The data were analysed on 105 patients with age over 5 years (182 shoulders) from August 1994 to December 2004. Surgical techniques performed by the author were divided into four types: (i) type I, proximal release of intermediate portion of deltoid muscle; (ii) type II, distal release of intermediate portion of deltoid muscle; (iii) type III, lengthening of intermediate portion of deltoid muscle; and (iv) type IV, distal release of intermediate portion of deltoid muscle and transfer of posterior portion of deltoid muscle to fill the gap. Accordingly, clinical and functional results were compared among four groups. The average duration of follow-up was 3 years and 2 months (range, 2-9 years and 5 months). Overall, in 174 shoulders (95.6%, 99 patients), we had a good clinical result; in two shoulders (1.1%, two patients) a fair result; and poor result in only six shoulders (3.3%, four patients). Postoperative formation of stairstep deformity or loss of roundness of the lateral aspect of shoulder in type I: 46.2%; type II: 30.3%; type III: 16.7%; type IV: 4.3%. Generally, surgical treatment gave good results. Technique type IV had reduced rate of stairstep deformity or loss of the natural roundness of the lateral aspect of the shoulder muscle. Sixty-eight patients (98.6%) in this group achieved a satisfactory outcome.     

Extensile approach to the anterolateral surface of the humerus and the radial nerve

A proposed approach to the anterolateral surface of the humeral shaft that would allow for exploration of the radial nerve was studied in 30 cadaver arms. The incision starts proximally along the posterior border of the deltoid muscle and extends anteriorly and distally over the lateral border of the biceps muscle. A deep dissection is made in the internervous plane between the deltoid and the triceps muscles proximally and between the longitudinally split fibers of the brachialis muscle distally. The approach provides access to the anterolateral surface of the humerus up to the level of the axillary nerve and the posterior circumflex humeral vessels. The insertion of the deltoid muscle into the anterior border of the humerus is preserved and the radial nerve is protected by the triceps muscle proximally and by the retracted lateral portion of the brachialis muscle distally. The entire course of the radial nerve in the arm can be exposed. Proximally, the radial nerve can be exposed by elevating the lateral head of the triceps muscle from the humerus. Distally, the radial nerve can be exposed between the brachioradialis and the brachialis muscles. A plate can be applied on the anterolateral surface of the humerus without having to elevate the firmly attached anterior deltoid insertion.     

A cadaveric study on the anatomy of the deltoid insertion and its relationship to the deltopectoral approach to the proximal humerus

Elevation of the deltoid insertion (DI) has been recommended, but little is known about its anatomy or importance for deltoid function. The purpose of this study is to determine the dimensions of the DI with specific reference to the deltopectoral approach. The deltoid was exposed and detached at its origin in 36 cadaveric shoulders. The morphology of the DI was documented, and its relationship with the pectoralis major insertion and the axillary and radial nerves was recorded. The anterior, middle, and posterior deltoid muscle fibers entered into the DI in a V-shaped tendinous confluence with a broad posterior band and a narrow separate anterior band, which accounted for the anterior one fifth of the DI (0.44 cm). The deltoid insertion was separated from the pectoralis major insertion by as little as 2 mm in 31 of 36 specimens. The distance between the axillary nerve and the DI averaged 5.6 cm anteriorly and 4.5 cm posteriorly. The distance between the radial nerve and posterior deltoid insertion averaged 2.4 cm proximally and 1.6 cm distally. Exposure during the deltopectoral approach is most limited by the close proximity of the deltoid and pectoralis major insertions. Our study would suggest that partial anterior DI release (greater than one fifth) could compromise the anterior deltoid. The axillary and radial nerves are not at significant risk when operating in the region of the anterior DI.     

Analysis of posterior deltoid function one year after surgical restoration of elbow extension

PURPOSE: The purpose of this study was to measure the extent and timing of elbow extension torque recovery after posterior deltoid-to-triceps tendon transfer. METHODS: Elbow extension moment was measured in 40 limbs from 23 patients who underwent surgical restoration using the posterior deltoid-to-triceps tendon transfer at times ranging from 8 weeks to 1 year after surgery. For comparison purposes, elbow extension moment also was measured in healthy controls and persons with C7 spinal cord injuries. RESULTS: Maximum extension moment was 5.89 +/- 0.24 Nm (mean +/- standard error of mean, n = 40), which corresponds to approximately 65% of the predicted posterior deltoid force and provided an adequate moment to oppose gravity. Based on the shape of the moment-joint angle curve and using a biomechanical model, it was predicted that posterior deltoid was inserted at a relatively short muscle length of 123.1 mm and thus operated exclusively on the ascending limb of the length-tension relationship. CONCLUSIONS: These observations support an evolving model of muscle architecture in which connective tissue septa restrict muscle fiber elongation during surgical tensioning of the tendon transfer. This relatively short length would result in a significant force loss should any of the repair sites slip or stretch during rehabilitation. These data have implications for the reconstruction and rehabilitation of this patient population.     

Proximal humerus exposure with the inverted-L anterolateral deltoid flip approach,anterolateral deltoid splitting approach,and deltopectoral approach: A comparative cadaveric study

BackgroundReduction of the posterior aspect of proximal humerus fracture, such as far-retracted greater tuberosity or posterior articular head split fracture via a deltopectoral or deltoid splitting approach, is difficult and usually needs extensive dissection. The inverted-L anterolateral deltoid flip approach, which is developed from the deltoid splitting approach, accesses the proximal humerus via lateral deltoid flap lifting. This study compared the area and arc of surgical exposure to the proximal humerus of this proposed approach to existing approaches.MethodsEleven cadaveric specimens were used. Deltopectoral and deltoid splitting approaches were carried out on the right and left shoulder, respectively. Soft tissue was retracted after completion of a surgical approach to expose the proximal humerus, and dot-to-dot marking pins were placed along the border of exposed area. An additional area with a full shoulder rotation was also marked on the deltopectoral side. An inverted-L deltoid flip approach was further carried out on a deltoid splitting side with a posterior extending incision along the acromion process and the deltoid detachment from the acromion process. The additional area of exposure was subsequently marked. All soft tissue around the proximal humerus was taken down, and the glenohumeral joint was disarticulated. Area of exposure and axial images were taken for further processing and measurement.ResultAn average distance of the axillary nerve from the acromion process of the deltoid splitting and the deltopectoral approaches were 49.15 mm and 57.35 mm, respectively (P < 0.05). The average area of exposure of the inverted-L deltoid flip, deltoid-splitting, deltopectoral, and deltopectoral with full rotation approaches were 2729.81mm², 1404.39mm², 1325.41mm², and 2354.78mm², respectively (P < 0.05). Mean arc of exposure lateral to bicipital groove of the inverted-L deltoid flip, deltoid splitting, deltopectoral, and deltopectoral with full rotation approaches were 151.75degrees, 105.02degrees, 61.68°, and 110.64°, respectively (P < 0.05).ConclusionThe inverted-L anterolateral deltoid flip approach provides the most posterior access to the proximal humerus. However, it requires more soft tissue dissection and awareness of tension on the axillary nerve. This approach could be an alternative for displaced posterior head splits or far-retracted greater tuberosity proximal humerus fractures.     

Henry's Pelvic Deltoid: Antiquated Concept or Important Consideration for Total Hip Arthroplasty? : An Anatomical Study

The relevance of Henry's pelvic deltoid and its contribution to hip abductor strength is often not considered in hip arthroplasty. This small cadaveric study (n = 11) aimed to quantify the relative contributions of the pelvic deltoid muscles to abductor strength and to assess how different surgical approaches(anterolateral, direct lateral and posterior) impact on each of these muscle groups. We inspected the path of each approach and measured the cross-sectional area of the hip abductors, from which the contribution of each muscle to abductor moment was derived. We concluded that the posterior approach has the least impact on the pelvic deltoid and overall abductor moment.     

Microdialysis of paraspinal muscle in healthy volunteers and patients underwent posterior lumbar fusion surgery

Paraspinal muscle damage is inevitable during conventional posterior lumbar fusion surgery. Minimal invasive surgery is postulated to result in less muscle damage and better outcome. The aim of this study was to monitor metabolic changes of the paraspinal muscle and to evaluate paraspinal muscle damage during surgery using microdialysis (MD). The basic interstitial metabolisms of the paraspinal muscle and the deltoid muscle were monitored using the MD technique in eight patients, who underwent posterior lumbar fusion surgery (six male and two female, median age 57.7 years, range 37–74) and eight healthy individuals for different positions (five male and three female, age 24.1 ± 0.8 years). Concentrations of glucose, glycerol, and lactate pyruvate ratio (L/P) in both tissues were compared. In the healthy group, the glucose and glycerol concentrations and L/P were unchanged in the paraspinal muscle when the body position changed from prone to supine. The glucose concentration and L/P were stable in the paraspinal muscle during the surgery. Glycerol concentrations increased significantly to 243.0 ± 144.1 μM in the paraspinal muscle and 118.9 ± 79.8 μM in the deltoid muscle in the surgery group. Mean glycerol concentration difference (GCD) between the paraspinal muscle and the deltoid tissue was 124.1 μM (P = 0.003, with 95% confidence interval 83.4–164.9 μM). The key metabolism of paraspinal muscle can be monitored by MD during the conventional posterior lumbar fusion surgery. The glycerol concentration in the paraspinal muscle is markedly increased compared with the deltoid muscle during the surgery. It is proposed that GCD can be used to evaluate surgery related paraspinal muscle damage. Changing body position did not affect the paraspinal muscle metabolism in the healthy subjects.     

Effect of fore-aft seat position on shoulder demands during wheelchair propulsion: part 2. An electromyographic analysis

BACKGROUND/OBJECTIVES: Shoulder pain is common in persons with complete spinal cord injury. Adjustment of the wheelchair-user interface has been thought to reduce shoulder demands. The purpose of this study was to quantify the effect of seat fore-aft position on shoulder muscle activity during wheelchair propulsion. METHODS: Shoulder electromyography (EMG) was recorded while 13 men with paraplegia propelled a wheelchair in the following 2 seat positions: (a) shoulder joint center aligned with the wheel axle (anterior) and (b) shoulder joint center 8 cm posterior to the wheel axle (posterior) in 3 test conditions (free, fast, and graded). Duration of EMG activity and median and peak intensities were compared. RESULTS: During free propulsion, the median EMG intensity of all muscles was similar between anterior and posterior seat positions. The major propulsive muscles (pectoralis major and anterior deltoid) demonstrated significant reductions in their median and peak intensities in the posterior seat position. Pectoralis major median intensity was significantly reduced in the posterior position during fast (52% vs 66% maximal muscle test [MMT]) and graded (41 % vs 49% MMT) conditions, and peak intensity was significantly reduced in the free condition (29% vs 52% MMT) and the fast condition (103% vs 150% MMT). Anterior deltoid intensity was significantly reduced in the posterior position during fast propulsion only (26% vs 31% MMT). For all muscles, EMG duration was similar between positions in all test conditions. CONCLUSIONS: Reduction in the intensity of the primary push phase muscles (pectoralis major and anterior deltoid) during high-demand activities of fast and graded propulsion may reduce the potential for shoulder muscle fatigue and injuries.     

Minimally invasive lateral plate placement for metadiaphyseal fractures of the humerus and its implications for the distal deltoid insertion- it is not only about the radial nerve. A cadaveric study

IntroductionMinimally invasive lateral placement of plates on the humerus may be associated with a risk of injury to the radial nerve. Whereas this potential complication has been investigated in several studies, there is no data regarding potential injuries to the distal insertion of the deltoid muscle when the plates are passed distally in a submuscular tunnel.MethodsMinimally invasive plate placement was performed on eight arms in fresh cadavers. A lateral deltoid split approach was made and the plates were introduced in an antegrade submuscular manner from proximal to distal. A lateral distal incison was made to adjust the position of the plate at the lateral aspect of the humerus without formal exploration of the radial nerve. The arms were dissected to identify the seven intramuscular tendons of the deltoid and their insertions at the humerus. The position of the plate and its relation to the intramuscular tendons of the deltoid was explored. Furthermore, potential injuries to the axillary and radial nerve were investigated. Damage to the brachialis muscle its interference with plate positioning were explored.ResultsThe distal deltoid insertion was affected in all eight examined arms. The two most anterior and two most posterior segments were intact in all. In two arms, the third intramuscular tendon was perforated. In three specimens, the insertion of the fourth segment was damaged. The fifth segment was partially disrupted in three arms. Overall, injuries to the intramuscular tendons were limited to one tendon in all arms. Partial brachial muscle entrapment underneath the plate was observed in four specimens. The axillary nerve was not damaged in any of the examined arms. The radial nerve was entrapped between plate and humeral shaft in one case.ConclusionsLateral plate placement in MIPO technique damages central parts of the distal deltoid muscle insertion. However, the most anterior and posterior tendons are not involved and the clinical significance on muscle function remains unclear. Introduction of the plate without prior distal incision and elevation of the brachial muscle may be associated with partial entrapment of the brachial muscle and a higher risk of injuring the radial nerve.Level of evidenceExperimental study.     

颈髓损伤四肢瘫的上肢功能重建

对颈椎颈髓损伤致四肢瘫病人,在后期脊髓功能恢复无望的情况下,通过肌转位等手术改善上肢残存功能,提高其生活质量。自1993年以来我们对16例四肢瘫病人20侧肢体作上肢功能重建术,包括代三头肌术8例,代指深屈肌术15例,代拇长屈肌术7例,均取得满意疗效。认为在手部屈指功能重建应优先于拇指侧捏功能重建,并应重视此类病人伸肘功能的重建。对三角肌后部纤维代肱三头肌术作了较详细的介绍。     

Transacromial approach for implantation of shoulder prostheses

Surgical Principles Temporary release of the acromial part of the deltoid muscle together with the posterior and medial bony edge of the acromion. Optimal visualization of all areas of the joint for insertion of prosthesis and reconstruction of ruptured rotator cuffs. This approach is a variation of the transacromial approach described by DePalma [9]. Revised Version from: Operat. Orthop. Traumatol. 2 (1990), 105–116 (German Edition).