Morphology and dynamics of the ulnar nerve in the cubital tunnel. Observation by ultrasonography

We examined 200 normal elbows to assess the usefulness of ultrasonography in examining the ulnar nerve in the cubital tunnel. On longitudinal images in elbow extension, the nerve changed its course at the fibrous band region 11.5 (SD 2.8) mm distal to the medial epicondyle. On axial images, the diameter of the major axis of the nerve was 3.1 (0.5) mm and that of the minor axis was 1.9 (0.4) mm in men. The respective values were 2.7 (0.4) mm and 1.8 (0.4) mm in women. Dynamic studies showed that in 53 elbows (27%), the nerve moved on to the tip of the epicondyle with the elbow flexed and in 39 elbows (20%), the nerve dislocated anteriorly. The diameters of the hypermobile nerves were significantly larger than nerves that did not displace.     

Recurrent ulnar-nerve dislocation at the elbow.

Recurring luxation of the ulnar nerve at the elbow is not uncommon (16.2%), occurring about equally in young and old, male and female, athletes and non-athletes but the greater mobility is usually at the dominant arm. The probable cause of such dislocation is congenital laxity of supporting ligaments. Being more vulnerable to injury than normally-positioned nerves, however, complicating neuritis can does occur. Subluxating nerves which stop on the tip of the medial humeral epicondyle upon 90 degrees or more of flexion at the elbow are more subject to direct trauma than completely displaced neural structures which cross the epicondyle upon elbow flexion. The latter may develop friction neuritis which occurs most frequently in industrial workers and occasionally requires surgical transfer. Deep intramuscular implantation, with or without neurolysis, is definetely superior to subcutaneous placement of the affected nerve. In this report are described chemically-induced ulnar neuritis from cortisone injections about the medial humeral epicondyle; pressure ulnar neuritis in patients with enforced bed rest and from improper positioning on operating table with permanent neural deficit and the relationship of such hypermobile ulnar nerves to extension-flexion (whiplash) trauma to the neck. It is emphasized that most of these complications could have been avoided had the patient and his physician known that such anomalies were present. Of particular importance is the avoidance of pressure to the medial aspect of a flexed elbow in surgical patients under general anesthesia. The unrelated co-existence of intermittently-symptomatic hypermobile ulnar nerves and extension-flexion neck trauma may occur. Recognition of isolated unlar neuritis in these patients is definitely important from the diagnostic, treatment and medical-legal aspects of such cervical spine injuries.     

Elbow dislocation with avulsion of the medial humeral epicondyle

After dislocation of the elbow with avulsion of the medial epicondyle, the management of the latter is controversial. Of 28 children followed up after initial closed reduction of the elbow, 19 had a satisfactory closed reduction of the epicondyle and were treated in plaster. At follow-up, 11 children had a normal elbow and eight had lost an average of 15 degrees of flexion. Nine children had had open reduction and internal fixation of the fragment, one for an open injury, three for displacement of the epicondyle and six for intra-articular entrapment of the fragment. Five of these children had ulnar nerve contusion or compression, four requiring anterior transposition of the nerve. At review, only three had normal elbows and six had lost an average of 37 degrees of flexion. We agree with other authors that surgery is indicated only for children in whom the epicondyle is trapped in the joint or is significantly displaced after closed reduction.     

Untreated intra-articular entrapment of the medial humeral epicondyle

Six children with entrapment of the medial epicondyle in the elbow after closed reduction of a posterior dislocation were seen an average of 14 weeks after injury. The elbows were painful and the average range of flexion was 22 degrees. Two children had ulnar nerve involvement which recovered after operation. The epicondyle was removed from the joint and either reattached to the humerus or excised, and the muscles reattached. Two children had anterior transposition of the ulnar nerve, one for pre-operative hyperaesthesia, and the other to relieve tension on the nerve. At follow-up, at an average of 15 months after operation, flexion had increased fivefold, none of the children had pain and all were leading normal lives.     

肘管综合征的应用解剖学研究

目的 研究肘管综合征中尺神经的卡压因素,为临床手术提供解剖学依据.方法 采用解剖学方法对16具(32侧)成人尸体上肢标本进行解剖,观测造成尺神经卡压的Struthers弓形组织、内侧肌间隔和肘管,测量肘管内尺神经的面积、肘管的面积和肘管的长度,测量弓状韧带的长、宽和厚度.观测尺神经的营养血管及伴行长度,观测尺神经的尺侧腕屈肌肌支.结果 32侧上肢标本中12侧存在腱性Struthers弓形组织,10侧有肌性Struthers弓形组织,存在率为68.8%.尺神经在内上髁上方[(11.02±1.16)cm,小x±s.下同]处穿内侧肌间隔,尺神经肘管内面积与肘管面积之比为1:3.86,肘管长度为(1.96±0.18)cm.尺神经伴行血管有尺侧上副动脉和尺侧返动脉后支,尺神经在内上髁下方1cm左右发出尺侧腕屈肌肌支.结论 尺神经在肘管处最容易受压,手术治疗肘管综合征时向上的切口长度约为11.02cm,同时切除Struthers弓形组织和内侧肌间隔;尺神经前置手术时,注意保留与神经伴行的尺侧返动脉后支.     

High-definition magnetic resonance images on medial elbow injuries in preadolescent Little Leaguers

BackgroundThe incidence of throwing-related elbow injuries is still rising. The study aimed to enhance the pathology of acute medial elbow injuries among young Little Leaguers by examining the medial elbows of symptomatic 9–10 years old Little Leaguers using High-Definition Magnetic Resonance Images (HDMRI), which uses a small-diameter surface coil on the target area, leading to greater image resolution.MethodWe identified Little Leaguers aged 9–10 years old. To minimize the detection of the chronic adaptative changes, players who experienced the medial elbow pain previously and whose HDMRI had not been taken within 4 weeks from the onset of medial elbow pain were excluded. This study considered 21 players, and the mean age was 9.4 ± 0.5 years.ResultThe fragmentation of the medial epicondyle apophysis via HDMRI was found in 15 elbows (71.4%), while the avulsion was seen in three cases. The signal hyperintensity at the medial epicondyle apophysis was observed in 2 cases. Our data showed abnormal changes to the medial epicondyle apophysis and surrounding structures, such as the ulnar collateral ligament (UCL), flexor-pronator tendons or the coronoid process of the ulna. We detected 11 abnormalities on X-ray imaging, while 20 subjects showed some abnormal findings via HDMRI.DiscussionThe current study showed that initial medial elbow injury in Little Leaguers without a history of previous elbow injury could be attributed to multi-structure injury. Over 90% of subjects were injured in the perichondrium, while 71.4% demonstrated a fragmentation of the secondary ossification center, and 14.3% experienced an avulsion of the medial epicondyle apophysis. Because the injuries were not limited to bony structures, HDMRI may be beneficial for the appropriate evaluation of medial elbow pain. The pathology of initial medial elbow injuries in young baseball players may be due to acute trauma instead of repetitive microtrauma.     

The cubital tunnel: anatomic, histologic, and biomechanical study.

The anatomy of the cubital tunnel was examined in 19 human cadaveric elbows. Pressure measurements within the cubital tunnel were recorded at the medial epicondyle level and 3 cm distal to the epicondyle in various positions of elbow flexion. Histologic examination of the ulnar nerve was carried out at different levels. A common flexor aponeurosis (CFA) was consistently present in all specimens between the flexor carpi ulnaris and the flexor digitorum superficialis. Pressure measurements were greater distally at the CFA level than proximally in the fibrosseous tunnel. The pressure inside the cubital tunnel increased with increasing flexion at the 3 levels examined. Releasing the arcuate ligament decreased the pressure in the fibrosseous tunnel but not distally at the level of the CFA. An oligofascicular pattern of the ulnar nerve was observed at the level of the medial epicondyle and CFA. This finding was in contrast to the polyfascicular pattern present both proximal and distal to these structures. The findings of our study have shown that an intimate anatomic relationship exists between the ulnar nerve and the CFA. This proximity appears to affect the biomechanics of the cubital tunnel and to contribute to nerve compression by the CFA in the distal tunnel. We also found that elbow flexion increases the pressure in the distal tunnel and that releasing the arcuate ligament alone does not decompress the ulnar nerve in the distal tunnel.     

Intraoperative measurement of pressure adjacent to the ulnar nerve in patients with cubital tunnel syndrome

PURPOSE: Little is known about whether the pressure adjacent to the ulnar nerve actually is increased in patients with cubital tunnel syndrome or if it is a causative factor. We measured the pressure adjacent to the ulnar nerve in patients with cubital tunnel syndrome during surgery and verified whether or not there was an association with patient age, duration of the disease, motor nerve conduction velocity, and severity of the ulnar nerve neuropathy. METHODS: Eight elbows in 8 patients with an average age of 62 years were treated surgically and the extraneural pressures within the cubital tunnel were measured during surgery by using a fiberoptic microtransducer. Pressure was measured 3 times with the elbow fully extended and then 3 times with the elbow flexed 130 degrees. The transducers were placed at 1, 2, and 3 cm distal to the proximal edge of the Osborne ligament. The severity of the neuropathy was evaluated according to Akahori's classification. The ulnar nerve palsy was graded as stage III in 5 patients and as stage IV in 3 patients. RESULTS: The average pressures within the cubital tunnel at 1, 2, and 3 cm distal to the proximal edge of the cubital tunnel retinaculum with the elbow flexed were 105, 29, and 18 mm Hg, respectively. The pressures at 1 and 2 cm distal to the proximal edge of the cubital tunnel retinaculum were significantly higher in elbow flexion than in elbow extension. There was also a positive correlation between the pressure and patient age but this was not significant The pressures correlated significantly with the stage of ulnar nerve neuropathy, motor nerve conduction velocity, and disease duration. CONCLUSIONS: The extraneural pressure within the cubital tunnel actually was increased in the patients and compression of the ulnar nerve might be a causative factor of cubital tunnel syndrome.     

Ulnar nerve strains at the elbow: the effect of in situ decompression and medial epicondylectomy

Strains were measured in the ulnar nerve at the elbow in 10 unembalmed, intact cadavers by using a microstrain gauge. In each cadaver, strains in the ulnar nerve behind the medial epicondyle, occurring between 60 degrees and 140 degrees flexion, were calculated for the following 3 conditions: (1) initial strain before in situ decompression, (2) strain after in situ decompression, and (3) strain after in situ decompression plus medial epicondylectomy. The average strain for each group was compared by using the paired Students t-test with multiple comparisons. The average initial percent strain was not significantly reduced by in situ decompression alone (5.3% to 4.3%). However, the average percent strain after medial epicondylectomy and in situ decompression was -0.54%, which was a significant reduction from the initial percent strain and after decompression alone. In situ decompression of the ulnar nerve at the elbow alone does not relieve the tensile strains at the elbow, which may contribute to cubital tunnel syndrome. Medial epicondylectomy after in situ decompression eliminates ulnar nerve strains with elbow flexion.     

The cubital tunnel and ulnar neuropathy

The anatomy of the cubital tunnel and its relationship to ulnar nerve compression is not well documented. In 27 cadaver elbows the proximal edge of the roof of the cubital tunnel was formed by a fibrous band that we call the cubital tunnel retinaculum (CTR). The band is about 4 mm wide, extending from the medial epicondyle to the olecranon, and perpendicular to the flexor carpi ulnaris aponeurosis. Variations in the CTR were classified into four types. In type 0 (n = 1) the CTR was absent. In type Ia (n = 17), the retinaculum was lax in extension and taut in full flexion. In type Ib (n = 6) it was tight in positions short of full flexion (90 degrees to 120 degrees). In type II (n = 3) it was replaced by a muscle, the anconeus epitrochlearis. The CTR appears to be a remnant of the anconeus epitrochlearis muscle and its function is to hold the ulnar nerve in position. Variations in the anatomy of the CTR may explain certain types of ulnar neuropathy. Its absence (type 0 CTR) permits ulnar nerve displacement. Type Ia is normal and does not cause ulnar neuropathy. Type Ib can cause dynamic nerve compression with elbow flexion. Type II may be associated with static compression due to the bulk of the anconeus epitrochlearis muscle.     

Use of ultrasonography in ulnar nerve entrapment surgery—a prospective study

The purpose of our study is to assess the usefulness of high-resolution ultrasonography in observing the morphology and dynamics of the ulnar nerve in the cubital tunnel and also the efficacy of ultrasonography in a more accurate diagnosis and appropriate surgical treatment decision. Cross-sectional area of the ulnar nerves of 40 healthy volunteers in the control group were measured bilaterally at the level of the epicondyle, 2 cm proximal to and 2 cm distal to the epicondyle. Measurements were obtained for elbows both in extension and flexion. Then, we prospectively obtained the cross-sectional area values of 18 patients at the same levels, elbows in extension and flexion position, and compared the data obtained from the patient group and the control group. The differences between the cross-sectional areas of the ulnar nerves in extension and flexion were statistically significant in the patient population (p < 0.001). Mean cross-sectional area of the ulnar nerve in the patient population was calculated as 0.16 cm², and we accepted the cut-off point as 0.1 cm². This value for cross-sectional area yielded a sensitivity of 90% and a specificity of 100% in diagnosis of ulnar nerve entrapment. Results substantiated conspicuous morphological changes in ulnar nerve during flexion and extension of the elbow. We also observed that as the degree of the nerve displacement by virtue of elbow flexion that is discerned by ultrasonography increased, a more aggressive decompressive surgery was needed for an appropriate treatment.     

Origin of the medial ulnar collateral ligament.

The anatomic features of the origin of the anterior medial collateral ligament of the elbow were studied in 10 cadaver elbows to determine the percentage of the medial epicondyle that can be removed without violating the ligament, and whether or not this ligament attaches to the condyle as well as to the epicondyle. In all specimens the anterior medial collateral ligament originated exclusively from the anteroinferior surface of medial epicondyle and had no attachment to the condyle. Only 20% of the width of the medial epicondyle in the coronal plane can be removed without violating a portion of the origin of the anterior medial collateral ligament, an essential stabilizer of the elbow. Excision of the entire epicondyle for ulnar neuropathy would completely detach this ligament from its origin and might therefore potentiate instability. Since the ligament originates on the anteroinferior surface of the epicondyle, more bone can be removed with less violation of the anterior medial collateral ligament origin if the plane of the osteotomy lies between the sagittal and coronal planes.     

前臂内侧皮神经后支与肘管综合征手术切口的解剖关系

目的 观察肘部前臂内侧皮神经(medial antebrachial cutaneous nerve,MACN)后支的解剖特征,探讨在肘管综合征松解手术中防止其医源性损伤的方法.方法 解剖10具(20侧)成人上肢标本,并对12例肘管综合征手术患者,在肱骨内上髁远、近各8 cm范围内,观察NACN后支的数目、横跨角度并测定其与手术切口(内上髁前1 cm)的交汇部位.结果 32侧肢体共记录到62支MACN 后支,平均每侧肢体为1.9支.其中1支者8侧(25.0%,均位于内上髁远侧),2支者19侧(59.4%),3支者4侧(12.5%),4支者1侧(3.1%).位于内上髁下方者37支(59.7%),内上髁上方者25支(40.3%).这些后支与切口线的交角均大于45°,即皮神经是横向跨过切口线的.所有标本(100%)均至少有1支后支从内上髁远侧跨过切口线,其距内上髁的平均距离为[(2.9±2.3)cm,x-±s,下同];在68.8%的标本中至少有1支后支从内上髁近侧跨过切口线,其距内上髁的平均距离为(2.1±1.8)cm.结论 MACN后支至少有1支横跨肘管综合征的手术切口线,了解其位置关系并在皮下组织中仔细解剖分出保护,有助于避免误伤.     

Effect of elbow position on canine flexor digitorum profundus tendon tension.

Tendon injury in the finger remains a clinical challenge to hand surgeons. A canine model is commonly used to study biological effects of tendon injuries and their treatment. There is an important anatomical difference between human and canine anatomy that may be overlooked, however, namely that most of the flexor digitorum profundus (FDP) muscle in dogs takes its origin from the medial epicondyle of the humerus, whereas in humans this muscle arises purely from the forearm. Therefore, elbow position can affect the tension of this muscle in dogs, while having no effect in humans. The purpose of this study was to measure the effect of elbow position on tendon tension in the canine digit in vitro. Elbow position had a significant effect on tendon tension. Digit motion with the elbow fully flexed resulted in significantly higher tendon tension compared to digit motion with the elbow flexed 90 degrees or fully extended, regardless of digit or wrist position (p<0.05). The tension with the elbow flexed 90 degrees was also significantly higher than with the elbow fully extended (p<0.05). The maximum tendon tension with the elbow fully flexed was more than eight times larger than that of the fully extended elbow (p<0.05). We conclude that, in the canine model, elbow position is an important parameter that affects the passive tension applied to the flexor digitorum profundus, and, by implication, to any repair of that tendon. Dog flexor tendon rehabilitation protocols should therefore specify elbow position, in addition to wrist and digit position.     

Five- to thirteen-year follow-up of the GSB III total elbow arthroplasty

Between 1988 and 1995, the senior author performed total elbow arthroplasty in 28 elbows (23 patients) with the GSB III prosthesis. At the most recent follow-up, 7 patients had died (9 elbows) and 1 had the implant removed because of a deep infection. The remaining 18 elbows (15 patients) were available for clinical and radiographic review at a mean period of 7.6 years (range, 5.5-11.9 years). All 15 patients were satisfied with the results of their elbow replacement, with a mean Mayo elbow performance score of 91 (range, 75-100). The mean flexion/extension and supination/pronation arcs improved by 33 degrees and 67 degrees, respectively. Radiographic follow-up demonstrated progressive loosening in only 1 patient and no progressive loosening in those with an adequate cement technique. Mild or moderate lysis of the distal humeral or proximal ulnar components was noted in 10 elbows, and severe lysis of the distal humerus was seen in 1. Of the patients, 6 (21%) had mild complications: triceps avulsions in 3, superficial wound infections in 2, and an undisplaced fracture of the distal humeral medial condyle in 1. In 4 patients (14%) complications developed requiring reoperation, including exchange of the polyethylene bushing because of wear, debridement of synovitis, resection arthroplasty for deep infection, and exploration of an ulnar nerve palsy. In 2 additional patients (7%), persistent ulnar nerve paresthesias developed postoperatively. Of the 28 elbow replacements performed with the GSB III prosthesis, only 1 required revision because of loosening at a mean follow-up of 7.6 years. The results of this series of GSB III elbow replacements in patients with rheumatoid arthritis demonstrate reasonable survivorship of this prosthesis.     

Ulnohumeral arthroplasty for primary degenerative arthritis of the elbow: long-term outcome and complications

BACKGROUND: Primary degenerative arthritis of the elbow is an uncommon disorder that recently has been more clearly recognized. The purpose of this study was to analyze the long-term results and complications of ulnohumeral arthroplasty as treatment of primary osteoarthritis of the elbow and to document any tendency for recurrence of the arthritis after the procedure. METHODS: The results of ulnohumeral arthroplasties performed at our institution, between 1986 and 1996, in forty-six elbows (forty-five patients) with primary osteoarthritis were reviewed at an average of eighty months (range, twenty-four to 164 months) after the operation. There were forty-four men and one woman with a mean age of forty-eight years. All patients complained of pain with terminal elbow extension. The pain was associated with locking in fourteen elbows and with ulnar nerve symptoms in twelve. The surgical procedure involved fenestration of the olecranon fossa and excision of olecranon and coronoid osteophytes in all patients, with removal of loose bodies in thirty-six elbows. A capsular release was performed in nineteen elbows, and an ulnar nerve transposition or neurolysis was done in eight. Preoperative and follow-up assessment included evaluation of elbow pain and range of motion with the Mayo Elbow Performance Score. RESULTS: The mean arc of flexion-extension improved from 79 degrees (range, 10 degrees to 135 degrees) preoperatively to 101 degrees (range, 45 degrees to 135 degrees) at the time of follow-up (p < 0.05). At the last follow-up examination, thirty-five elbows (76%) were not painful or were only mildly painful and eleven were moderately or severely painful. According to the Mayo Elbow Performance Score, the result was excellent for twenty-six elbows, good for eight, fair for four, and poor for eight. Thirteen of the forty-five patients reported some degree of ulnar nerve symptoms postoperatively, and six of them required another operation to decompress or translocate the nerve. Two other patients underwent additional surgery because of persistent symptoms. CONCLUSIONS: The data from this study show that ulnohumeral arthroplasty can yield satisfactory long-term pain relief and an increase in the range of motion. Patients with severe preoperative limitation of elbow extension of >60 degrees and flexion of <100 degrees and those who undergo manipulation under anesthesia in the early postoperative period to increase motion are at risk for the development of ulnar nerve dysfunction postoperatively. One should consider prophylactic ulnar nerve decompression or mobilization under these circumstances.     

Cubitus varus associated with dislocation of both the medial portion of the triceps and the ulnar nerve.

Five patients with cubitus varus deformities from malunited childhood fractures had dislocation (snapping) of both the medial portion of the triceps and the ulnar nerve over the medial epicondyle. In addition to snapping, these patients had medial elbow pain or ulnar nerve symptoms. Cubitus varus shifts the line of pull of the triceps more medial, which can cause anteromedial displacement of the medial portion of the triceps during elbow flexion. The ulnar nerve is concomitantly pushed or pulled anteromedially by the triceps, and ulnar neuropathy may result from friction neuritis or from dynamic compression by the triceps against the epicondyle. Recognition of both the dislocating ulnar nerve and the snapping medial triceps is crucial in the successful treatment of this pathologic finding. In symptomatic individuals, we recommend either corrective valgus osteotomy of the distal humerus or partial excision or lateral transposition of the snapping medial triceps, or a combination of both. Alternatively, medial epicondylectomy can also eliminate the snapping. Transposition of the ulnar nerve can be performed for ulnar nerve symptoms and/or ulnar nerve instability. Using this approach, correction of the snapping and/or ulnar nerve symptoms was achieved in all cases.     

Progressive surgical release of a posttraumatic stiff elbow. Technique and outcome after 2-18 years in 46 patients

We treated 46 consecutive patients (47 elbows) suffering from posttraumatic contracture of the elbow joint with operative release. A lateral approach was used to perform a capsulectomy after release of the extensor muscles in 23 elbows. An additional medial approach was used to excise ulnar adhesions and perform a more extensive capsulectomy and an ulnar nerve neurolysis in 24 elbows. Postoperative rehabilitation consisted of immediate passive range-of-motion exercises. The results were assessed after average 10 (2-18) years. Before surgery, the mean active arc of motion was 45 (SD 36) degrees, which improved to 99 (SD 34) degrees after release. 7 patients had transient ulnar paresthesia, 4 recurrent stiffness, which did not become worse after surgery, 1 was reoperated on and 2 developed a postoperative infection, which responded to antibiotic treatment after a few months. No patient suffered from joint instability, or an increase in pain. 44 patients were satisfied with the result at the latest follow-up. We found similar improvement in both treatment groups.     

Débridement arthroplasty for primary osteoarthritis of the elbow

BACKGROUND: Formal and more aggressive débridement procedures have been described for the treatment of advanced primary osteoarthritis of the elbow. However, the literature contains little information on the results of long-term follow-up. The purpose of this study was to evaluate outcomes at an average of ten years after débridement arthroplasties performed through a posteromedial approach. METHODS: Thirty-three elbows with primary osteoarthritis in thirty-two patients treated with débridement arthroplasty were available for clinical follow-up evaluation. Through a posteromedial approach, the flexor-pronator muscle origin was reflected from the medial epicondyle and the joint was opened, preserving the anterior oblique bundle of the medial collateral ligament. The ulnar nerve was decompressed in all patients. Osteophytes were removed from the anterior, medial, and posterior sides of the elbow joint. In nine elbows, osteophytes from the lateral compartment were removed through an additional lateral approach. The mean age at the time of the operation was fifty years. The mean duration of follow-up was 121 months, and nineteen elbows were followed for more than ten years. RESULTS: The mean preoperative limitation of extension of 31 degrees was reduced to 24 degrees, and the mean preoperative flexion of 101 degrees improved to 118 degrees (p < 0.001). The mean arc of movement improved by 24 degrees. The mean Japanese Orthopaedic Association elbow score was 83 points at the latest follow-up evaluation compared with 60 points preoperatively (p < 0.001). Of twenty-five patients who had performed heavy manual work, nineteen (76%) returned to their previous job or an equivalent job. At the latest examination of the nineteen elbows followed for more than ten years, the limitation of extension was found to have increased by 7 degrees compared with the limitation noted at one year (p < 0.009); the mean arc of flexion had remained the same. Three elbows required a reoperation. Overall, 85% of the elbows were satisfactory to the patients. CONCLUSIONS: Débridement arthroplasty through a posteromedial approach can provide stable and reliable long-term results with regard to relief of pain, gains in range of motion, and the patient's ability to return to his or her previous occupation. In our series, a modest loss of extension was observed at ten years, whereas the arc of flexion remained consistent.     

The ulnar nerve at the elbow and its local branching: an anatomic study

Thirty nine cadaver elbows were dissected and the branching of the ulnar nerve, as well as the cubital tunnel and adjacent potential sites of nerve compression were studied. An arcade of Struthers was present in 26 specimens and Osborne's ligament was present in all specimens. A discrete flexor pronator aponeurosis overlying the ulnar nerve was present in 17 specimens. An average of one (range, 0-3) capsular nerve branches were noted. These originated an average 7 mm proximal (range, 45 mm proximal to 24 mm distal) to the medial epicondyle. An average of three (range, 1-6) motor branches to the flexor carpi ulnaris muscle were noted, and one of these originated proximal to the medial epicondyle in two specimens. Significant variation was noted in the capsular and motor branching of the ulnar nerve. Care must be taken to identify the motor branches of the ulnar nerve when performing a transposition.