Compression neuropathy of the cubital nerve at the elbow]

Compression neuropathy of the ulnar nerve at the elbow has numerous known etiologies, and the anatomy of the ulnar nerve around the elbow leaves it vulnerable to compression at numerous sites. The compression may be extrinsic such as in occupational neuropathy or in cases of postanesthesia neuropathy. The so-called idiopathic compression may be favored by some anatomic variations. The cubital tunnel retinaculum may be loose, leading to ulnar nerve dislocation or subluxation or tight compression of the nerve during flexion of the elbow. Bulging of the synovium in the floor of the tunnel may be the cause of compression in rheumatoid arthritis, whereas osteophytes may be the cause in degenerative osteoarthritis. Cubitus valgus or instability due to a pseudarthrosis of the lateral epicondyle or to ligamentous injury may stretch the nerve. The choice of a surgical technique must be based on (i) the pathophysiology of chronic nerve compression at the elbow, (ii) an understanding of the etiology of the nerve compression in the particular patient's case, and (iii) the knowledge of the potential technical drawbacks of the various operative procedures. Simple decompression is the first choice in case of minimal compression without instability of the nerve. Decompression of the nerve with a medial epicondylectomy is indicated in case of instability of the nerve and is the first choice in case of pseudarthrosis or malunion of the medial epicondyle. Ulnar nerve transposition is technically the most demanding procedure. Inadequate surgical technique creates new sites of compression.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Minimal medial epicondylectomy and decompression for cubital tunnel syndrome.

Sixty-four patients (66 elbows) treated for refractory cubital tunnel syndrome had minimal medial epicondylectomy and in situ decompression to minimize the potential disadvantages of classic medial epicondylectomy. After a mean followup of 27 months results were excellent in 27 patients (44%), good in 23 patients (35%), fair in 10 patients (15%), and poor in four patients (6%). No ulnar nerve palsy, ulnar nerve subluxation, or medial elbow instability were seen. The main complaint of patients regarding the procedure was tenderness at the osteotomy site. The results show that minimal medial epicondylectomy and in situ decompression of the ulnar nerve is a safe and effective method to treat patients with cubital tunnel syndrome. This procedure minimizes the disadvantage of medial instability and recurrent symptoms attributable to nerve trauma after a classic medial epicondylectomy.     

Simple decompression of the ulnar nerve: an alternative to anterior transposition.

Anterior transposition and/or medial epicondylectomy are often considered procedures of choice for ulnar neuropathy at the elbow. Much experience suggests simple decompression to be a comparably effective alternative which involves less trauma, morbidity, and rehabilitation time. The post-operative clinical and electrophysiological results of 52 cases of simple decompression (41 patients) are summarized. Excellent or good clinical results were found in 75% of the nerves. Mean ulnar motor conduction velocities were significantly improved post-operatively, although nerve conduction parameters did not consistently correlate with clinical outcome. The average return-to-work time was 5.1 weeks. The advantages of simple decompression make it the procedure of choice for most cases of ulnar neuropathy.     

The effect of operative technique on ulnar nerve strain following surgery for cubital tunnel syndrome

Background

The aim of this study is to compare the amount of strain on the ulnar nerve based on elbow position after in situ release, subcutaneous transposition, submuscular transposition, and medial epicondylectomy.

Methods

Six matched cadaver upper extremity pairs underwent ulnar nerve decompression, transposition in a sequential fashion, while five elbows underwent medial epicondylectomy. A differential variable reluctance transducer (DVRT) was placed in the ulnar nerve. An in situ release, a subcutaneous transposition, and a submuscular transposition were performed sequentially with the strain being measured after each procedure in neutral, full elbow flexion, and extension positions. The strain was then averaged and compared for each procedure. Five cadavers underwent medial epicondylectomy and were similarly tested.

Results

After the in situ release, there was no statistically significant change in strain in either flexion or extension. After a subcutaneous transposition, there was a statistically significant decrease in strain in full elbow flexion but not in extension. Similarly after a submuscular transposition, there was a statistically significant decrease in strain in full flexion but not in extension. There was not a statistically significant change in strain with medial epicondylectomy.

Conclusion

An in situ release of the ulnar nerve at the elbow may relieve pressure on the nerve but does not address the problem of strain which may be the underlying pathology in many cases of ulnar neuropathy at the elbow (UNE). Transposition of the ulnar nerve anterior to the medial epicondyle addresses the problem of strain on the ulnar nerve. In addition, it does not create an increased strain on the ulnar nerve with elbow extension.     

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.     

Ulnar nerve decompression with medial epicondylectomy for neuropathy at the elbow.

Ulnar nerve decompression with medial epicondylectomy was performed in 66 elbows between 1966 and 1986 for compressive ulnar neuropathy at the elbow. This study is an updated review that adds 36 cases to a previously published report on 30 cases. These elbows were graded preoperatively and postoperatively using McGowan's grading system. Eighty-three percent improved one or two grades, and 11% improved subjectively although they showed no objective improvement, 3% noted no change, and 3% were subjectively worse. One early case sustained damage to the ulnar collateral ligament with resultant instability. No other complications occurred. The best results were seen in the Grade I and II lesions, whereas those with Grade III lesions were the least predictable. The procedure is technically uncomplicated with minimal morbidity and reliable results.     

The failed ulnar nerve transposition. Etiology and treatment

Various procedures have been recommended for the treatment of cubital tunnel syndrome. Simple decompression in situ, medial epicondylectomy, subcutaneous transposition, intramuscular transposition, and submuscular transposition all have their advocates. The results of the surgical treatment for cubital tunnel syndrome are related to the severity of the compressive neuropathy at the time of diagnosis and to the adequate decompression of the nerve at all sites of potential compression at the time of surgical treatment. Fourteen patients who had previously undergone surgical treatment for cubital tunnel syndrome were evaluated because of persistent pain, paresthesia, numbness, and motor weakness. All patients had documented persistent compression of the ulnar nerve on clinical and electromyographic evaluation. The indication for repeat surgical exploration in all patients was unremitting pain despite nonoperative treatment. All patients had been treated by neurolysis and submuscular transposition of the ulnar nerve as described by Learmonth. The causes of continued pain after initial surgery included retention of the medial intermuscular septum, dense perineural fibrosis of the nerve after intramuscular and subcutaneous transposition, adhesions of the nerve to the medial epicondylectomy site, and recurrent subluxation of the nerve over the medial epicondyle after subcutaneous transposition. Revision surgery was found to be highly successful for relief of pain and paresthesias; however, the recovery of motor function and return of sensibility were variable and unpredictable.     

Comparison between partial and minimal medial epicondylectomy combined with decompression for the treatment of cubital tunnel syndrome

We have performed minimal medial epicondylectomy for cubital tunnel syndrome since 1990 to preserve the anterior medial collateral ligament. In this study we compared surgical outcomes between partial medial epicondylectomy (14 patients) and minimal medial epicondylectomy (18 patients) combined with ulnar nerve decompression for the treatment of cubital tunnel syndrome. Mean preoperative Yasutake scores were 57 +/- 17 points (+/-SD) in the partial epicondylectomy group and 60 +/- 15 points in the minimal medial epicondylectomy group. The postoperative scores were 79 +/- 19 points and 87 +/- 10 points, respectively. Both groups had significant improvement in their Yasutake scores following medial epicondylectomy. Similar improvements in motor conduction velocity were observed. There was no significant difference in improvement of either the Yasutake scores or the motor conduction velocity between the 2 groups. Valgus instability of the elbow was significantly greater in the partial epicondylectomy group. We therefore conclude that minimal medial epicondylectomy combined with ulnar nerve decompression is an effective treatment for cubital tunnel syndrome and that a larger excision of the medial epicondyle should be avoided.     

Subcutaneous anterior transposition versus decompression and medial epicondylectomy for the treatment of cubital tunnel syndrome

A review of the literature often fails to uncover the best procedure for the treatment of cubital tunnel syndrome. This article compares 2 frequently used methods (subcutaneous anterior transposition vs decompression and medial epicondylectomy) for their effectiveness in relieving both subjective and objective symptoms of cubital tunnel syndrome. Between August 1991 and October 1993, nineteen patients underwent surgical decompression by a single surgeon for ulnar neuropathy at the elbow. Factors evaluated included upper extremity range of motion, elbow valgus stress, grip strength, pinch, 2-point discrimination, and pre- and postoperative nerve conduction. A standardized questionnaire was administered to assess subjective relief of symptoms.In the transposition group, grip strength averaged 71.2% of normal and pinch strength 86.6% of normal, and 2-point discrimination averaged 8.0 mm. The derived subjective assessment score was 23.2 of a possible 40. The average ulnar motor conduction velocity across the elbow was 50.1 m/sec preoperatively and 56.3 m/sec postoperatively. In the medial epicondylectomy group, grip strength averaged 79.5% of normal and pinch strength 81.7% of normal, and 2-point discrimination averaged 8.0 mm. The average ulnar motor conduction velocity across the elbow was 45.7 m/sec preoperatively and 55.7 m/sec postoperatively. No statistically significant difference existed between the 2 groups for the aforementioned indexes. These results do not indicate a difference between the outcomes of the patients undergoing either of the procedures. Because epicondylectomy is less technically demanding, with less soft tissue dissection of the nerve, it may be preferred over ulnar transposition.     

Surgical treatment of ulnar neuropathy.

Ulnar neuropathy is a well recognized clinical entity caused by a variety of pathological lesions around the elbow. The characteristic features include paresthesia and numbness in the little finger and medial half of the fourth digit, weakness of the small muscles of the hand innervated by the ulnar nerve, and a positive Tinel's sign. The diagnosis is confirmed by electrophysiological studies. Current methods of treatment are anterior transposition, neurolysis and medial epicondylectomy of the humerus. Forty-four patients with ulnar neuropathy are described in the present report. Most were males with a median age of 45. The left side was involved more frequently. Results of subcutaneous anterior transposition and medial epicondylectomy are presented along with a review of the literature.     

Ultrasound-guided surgical treatment for ulnar nerve entrapment: A cadaver study

Several open and endoscopic techniques for the surgical treatment of ulnar nerve entrapment at the elbow (cubital tunnel syndrome) have been described that provide decompression with or without anterior transposition. Based on our experience with US-guided decompression for carpal tunnel syndrome in our department, we developed a similar surgical technique for the decompression of the ulnar nerve at the elbow. Using sixteen cadaver upper limbs, we performed decompression of all the structures possibly responsible for ulnar nerve compression at the elbow. The structures involved were Struthers’ arcade, the cubital tunnel retinaculum, Osborne's fascia and Amadio-Beckenbaugh's arcade. The procedure was followed by anatomical dissection to confirm complete sectioning of the compressive structures, absence of iatrogenic vascular or nervous injuries and absence of nerve dislocation or instability. There were no remaining compressive structures after the release procedure. There was no iatrogenic damage to the nerves and no nerve dislocation was observed during elbow flexion or extension. In 3.4% cases, a thin superficial layer of one or more of the identified structures remained but these did not appear to compress the nerve based on US imaging. Using ultrasonographic visualization of the nerve and compressive structures is easy. Each procedure can be tailored according to the nerve compression sites. Our cadaveric study shows the feasibility of an US-guided percutaneous surgical release for ulnar nerve entrapment.     

Cubital tunnel syndrome. Treatment by decompression without transposition of ulnar nerve.

Cubital tunnel syndrome is the second most common entrapment neuropathy in the upper limb; however, surgical treatment of the ulnar nerve entrapment at the elbow remains controversial. None of the presently advocated procedures (simple decompression of the ulnar nerve, medial epicondylectomy, subcutaneous, submuscular or intramuscular anterior transposition of the ulnar nerve) has proven optimal regarding long-term results. This paper presents the experience of treating cubital tunnel syndrome with simple decompression in 40 patients. Three months after surgery 23/36 patients did not feel any pain in their operated hands. In 11/36 cases we observed an improvement of preoperative pain. Sensory disturbances disappeared completely in 24/40 cases. 11/40 patients reported an improvement of preoperative dysesthesia or hypesthesia. In 12/22 patients we observed complete recovery of preoperative pareses of adductor muscle of thumb or hypothenar muscles weakness. 7/22 cases demonstrated an improvement of these pareses. In total 28 patients (70 %) had an excellent outcome without residual symptoms. For 5 patients treatment results were classified as good with slight residual pain and sensory disturbance (12.5 %). In 4 cases (10 %) we only observed a fair outcome with persistent severe sensory and motor deficits but slow improvement over the last three months. Three patients did not demonstrate any improvement (7.5 %). The mean duration of postoperative disablement in our working patients (18/40) was 28 days. In summary, simple decompression of the ulnar nerve seems to be an adequate and successful minimally invasive technique for the treatment of cubital tunnel syndrome.     

Should we divide Osborn's ligament during epicondylectomy and in situ decompression of the ulnar nerve?

INTRODUCTION: Two groups of patients with cubital tunnel syndrome were treated by neurolysis and medial epicondylectomy. In the first group, the operative procedure consisted solely of dividing Osborn's ligament and fascia but in the second group Osborn's ligament was reinserted after epicondylectomy to avoid dislocation of the nerve. The aim of this retrospective study was to compare the level of complete recovery after surgery and the frequency of dislocation of the nerve. MATERIAL AND METHOD: Group one: Nineteen patients, with a mean age of 47.7 (15-65), and 52% female, with the dominant hand involved in 63% cases, were treated. According to Mac Gowan's criteria, 32% of the elbows were classified preoperatively as grade I, 52% as grade II and 16% as grade III. Sensory nerve conduction velocity across the elbow was less than 40 m/s in 40% of cases. The mean duration of the disease was longer than 3 years in 16% of cases. Group two: Twenty three patients, with a mean age of 54.1 (33-75), and 56% female, with the dominant hand involved in 56% cases, were treated. According to Mac Gowan's criteria, three 17% of the elbows were classified preoperatively as grade I, 47% as grade II and 34% as grade III. Sensory nerve conduction velocity across the elbow was less than 40 m/s in 60% of cases. The mean duration of the disease was longer than 3 years in 4% of cases. Both groups were evaluated by a surgeon not involved in the treatment by clinical examination and DASH scoring. RESULTS: DASH scoring is correlated with functional recovery, grip strength and Mac Gowan preoperative scoring. In group one, (divided and reinserted ligament) with younger patients, half the incidence of Mac Gowan stage II and a shorter follow up, there were no dislocations, but less complete resolution of preoperative symptoms (68%/82%) and a higher DASH scoring (30.6/24.9). In group two (resected ligament), dislocation of the nerve was noted in 17% of cases. In both groups, pain at the epicondylectomy site was noted in 20% of cases. The chance of complete recovery was inversely related to the age (>50), and to the duration of the disease (>1 year). DISCUSSION: Surgical treatment of ulnar nerve entrapment at the elbow remains controversial. None of the presently advocated procedures (simple decompression of the ulnar nerve, medial epicondylectomy or transposition of the ulnar nerve) has proven optimal regarding long-term results. In both groups in this study, neurolysis of ulnar nerve by section of Osborn's ligament and fascia together with medial epicondylectomy proved to be an effective surgical procedure for treating grade I to II ulnar neuropathy. Section of Osborn's ligament without its reattachment is followed by more cases of complete recovery as well as more dislocation of the nerve although the latter elicited no subjective complaints from the patients. DASH scoring is effective in evaluating the recovery.     

Risk factors for ulnar nerve compression at the elbow: a case control study

Summary Background. Ulnar nerve compression at the elbow is frequently encountered as the second most common compression neuropathy in the arm. As dexterity may be severely affected, the disease entity can seriously interfere with daily life and work. However, epidemiological research considering the risk factors is rarely performed. This study intended to investigate whether potential risk factors based on historical belief contribute to the development of ulnar nerve compression at the elbow. Method. A hospital based case control study was performed of patients that underwent surgical treatment for ulnar nerve compression at the elbow at the neurosurgical department from June 2004 until June 2005. Controls were those patients treated for a cervical or lumbar herniated disc. The main outcome measure was the presence of ulnar nerve compression at the elbow proven clinically, and electrodiagnostically. Results. 110 patients with ulnar nerve lesions and 192 controls were identified. Smoking, education level and related working experience were identified as risk factors. Conversely, gender, BMI, alcohol consumption, trauma to the elbow, diabetes mellitus, and hypertension are not risk factors for the development of ulnar nerve compression at the elbow. Conclusion. Risk factors are clearly defined. In the past many factors have been described, but mostly in surgical series. This study concludes that gender, previous fracture of the elbow and BMI are not predictive factors for ulnar entrapment neuropathy. However, education and working experience are closely correlated with this entity.     

Compression of the deep branch of the ulnar nerve in Guyon’s canal by a ganglion: two cases

INTRODUCTION: Ulnar nerve compression at the wrist can be caused by a variety of intrinsic and extrinsic factors. Isolated compression of only the deep branch of ulnar nerve by a ganglion is very uncommon. Ultrasound examination can clearly show the cystic lesion compressing the nerves. MATERIALS AND METHODS: We present two cases of compression of deep branch of ulnar nerve by a ganglion in the Guyon's canal. Two male patients presented with history of progressive weakness and paraesthesia in the medial 1(1/2) digits of the non-dominant hand. Interestingly, both the patients noticed sudden onset and rapid progress of the symptoms and signs. Clinical examination revealed typical symptoms of ulnar nerve (deep branch) palsy. Nerve conduction studies showed severe denervation of the deep branch of the ulnar nerves in both the patients and ultrasound confirmed the diagnosis. Surgical decompression led to complete recovery. RESULTS AND DISCUSSION: Whilst compression by a ganglion in the Guyon's canal is rare but well recognized, a feature of both of our cases was the rapid progression and severe nature of the compressive symptoms and signs. This is in contrast to the more typical features of compressive neuropathy and should alert the clinician to the possible underlying cause of compression. Early decompression has the potential to promote a complete recovery.     

Frontal partial epicondylectomy for release of the ulnar nerve at the elbow]

The author reports about an original technique of release of the ulnar nerve in the elbow by frontal partial epicondylectomy. In our opinion, this technique has the advantage of leaving a natural protection for the ulnar nerve when leaning on the internal aspect of the elbow. After summing up the various elements of ulnar nerve compression in the elbow and the various surgical techniques to remove compression, we describe in detail the surgical technique that we propose. The series is reported and the results are presented. These results are comparable to those of other published series and seem to depend mainly on the stage of nerve compression.     

Feasibility of a fascial flap to avoid anterior transposition of unstable Ulnar nerve: A cadaver study

BackgroundCompression of the ulnar nerve at the elbow is the second most frequent site of nerve compression in the upper limb. Upon release, anteposition of the nerve may be necessary to avoid dislocation of the latter when unstable. Numerous techniques are described in the literature (subcutaneous transposition, intramuscular transposition, subfascial transposition, medial epicondylectomy …), none of which is without complications. Based on Han's work, the authors propose a technique of covering the ulnar nerve with epicondylar fascial flap, avoiding transposition, but ensuring good stability of the ulnar nerve.MethodsAs part of the SICM (Italian Society of Hand Surgery) cadaver dissection course (ICLO, Verona, Italy) the authors dissected 36 elbows, of which 20 presented subluxation of the ulnar nerve after its decompression. The fascial flap was therefore made on these 20 elbows, coming from 14 different donors (9 men, 5 women) with an average age of 78 years. The diameter of the ulnar nerve was then measured (at the level of the passage in the cubital canal), the diameter of the newly formed canal, the difference between the two previous measurements (residual space in the flexed elbow canal), and it was verified whether the ulnar nerve was unstable once covered by the flap.ResultsThe mean diameter of the ulnar nerve was 5.1 mm (range 4–6), while the mean diameter of the neo-canal was 10.1 mm (range 8–11) in elbow extension and 8.9 mm (range 7–10) in elbow flexion. The remaining space in the flexed elbow canal was 3.8 mm (range 3–5).In none of the 20 cases the ulnar nerve was dislocated after having made the fascial flap.ConlusionsIn light of the results obtained, the authors think that the use of the epicondylar fascial flap may be a solution to keep in mind to avoid dislocation of the ulnar nerve when it becomes unstable following its decompression. This work obviously needs clinical confirmation on living patients.Level of evidenceV.     

Partial medial epicondylectomy for cubital tunnel syndrome: Outcome and complications

The results of partial medial epicondylectomy for cubital tunnel syndrome were evaluated in 60 elbows of 54 patients. Preoperatively, 8 patients were grade I, 24 grade IIA, 16 grade IIB, and 12 grade III according to the modified McGowan score (Goldberg BJ et al. JHand Surg [Am] 1989;14:182-8). Mean follow-up was 38.8 months. Special emphasis was placed on evaluation of 5 commonly reported drawbacks: medial elbow pain was related to the end result (P <.01), nerve vulnerability/subluxation might contribute to pain (P <.05), loss of force (approximately 15%) had no clinical implication, and flexion contracture and valgus instability were present in only 1 elbow. Eighty-three percent of our patients were better according to the Wilson and Krout score,(22) with 75% having excellent and good results. An improvement of at least 1 McGowan grade was obtained in 88.3%. The chance for complete recovery was inversely related to the initial neuropathy grade, as is consistently found throughout the literature for all types of cubital tunnel surgery. Partial medial epicondylectomy is a valuable surgical procedure for treating grade I to IIB ulnar neuropathy.     

Correlation between preoperative Kimura inching studies and intraoperative findings during endoscopic-assisted decompression of the ulnar nerve at the elbow

Background

During the evolution of the senior author's technique of ulnar nerve transposition to in situ decompression for ulnar neuropathy at the elbow, nerve conduction studies (NCS) including the Kimura inching method were performed preoperatively in an effort to ensure that all potential sites of compression were investigated intraoperatively. The purpose of this study is to compare the results of the Kimura inching technique with the intraoperative findings noted during decompression of the ulnar nerve at the elbow.

Methods

The medical records of consecutive patients who underwent in situ decompression of their ulnar nerves combined with endoscopic examination between March and December of 2009 were retrospectively reviewed. The site of ulnar nerve compression noted using the Kimura inching technique was compared with the intraoperative findings.

Results

Twelve consecutive patients (four with bilateral symptoms) underwent endoscopic ulnar nerve compression in the study period for a total of 16 cases analyzed. In 12 cases, the Kimura method localized the site of compression to Osborne's bands and/or the aponeurosis of the flexor carpi ulnaris (FCU). Intraoperatively, compression was noted at Osborne's bands, the FCU aponeurosis, and/or the FCU) muscle proper in all 16 patients. There was partial or full correlation between the nerve conduction data and intraoperative findings in 13/16 cases.

Conclusions

There was good but not perfect agreement between the NCS and intraoperative findings, perhaps because transcutaneous NCS are less accurate when a nerve is surrounded by muscle. The information obtained in this study is valuable when planning surgery to address ulnar nerve compression.