Severe Tardy Ulnar Nerve Palsy caused by Traumatic Cubitus Valgus Deformity: Functional Outcome of Subcutaneous Anterior Transposition

METHODS

From 1996 to 2003, 27 patients with symptoms and signs of ulnar neuropathy and a history of old elbow trauma were referred to our institution. The patients with valgus deformity and severe involvement of the ulnar nerve were enrolled in the study. Exclusions were as follows: a compressive neuropathy at another site, such as cervical radiculopathy, thoracic outlet syndrome or Guyon’s canal syndrome; concomitant hand neuropathies such as carpal tunnel syndrome; a systemic disorder capable of causing a non-compressive neuropathy, such as diabetes mellitus, chronic renal failure or hypothyroidism and a lack of a minimum follow-up of 1 year.

Patients were examined pre-operatively and the following data were noted: age, sex, hand dominance, occupation, a history of childhood elbow trauma and age at the time of trauma, and symptom duration. Roos’ manoeuvre and postural signs provoked by arm elevation were assessed routinely. Tinel’s test and the elbow flexion test (Buehler and Thayer, 1988) were also performed in all of the patients. Furthermore, supraclavicular tenderness and a supraclavicular Tinel’s sign were noted. Thoracic outlet syndrome on the same side was diagnosed according to accepted criteria (Novak et al., 1993). Anteroposterior and lateral radiographs of the elbow were obtained from all patients to evaluate the angle and the cause of valgus deformity. Non-unions of fractures of the lateral condyle of humerus were further classified according to Toh et al. (2002). Electrodiagnostic tests and routine laboratory tests were performed in all of the cases to confirm the diagnosis of cubital tunnel syndrome and exclude neuropathy caused by systemic disorders. Informed consent was obtained.

To assess the outcome of surgery, the following measures were carried out before the operation and at the final evaluation. The severity of ulnar nerve neuropathy was determined according to the grading system of McGowan (1950) and the modification by Goldberg et al. (1989). The patients were also evaluated for symptoms and signs of sensory and motor dysfunction including pain, hypaesthesia, paraesthesia and static two-point discrimination (2PD), limitation of function, intrinsic muscle weakness and intrinsic muscle atrophy. The severity of each symptom or sign was graded as presented in Table 1. For evaluation of intrinsic hand muscle atrophy, photographs of the affected hands were graded according to Table 1 by one of the authors (S.M.J.M.), who was unaware of patients’ identity. Electrodiagnostic studies were performed in the affected limbs to evaluate the conduction velocity of motor fibres of the ulnar nerve across the elbow (Table 1).

All of the patients underwent anterior subcutaneous transposition of the ulnar nerve as described by Eaton et al. (1980). The chief indication for operative management was an objective neurological deficit. Patients were allowed active elbow range of motion exercises only after 2 weeks of absolute immobilisation of the elbow in 90° flexion. All patients were seen at 1, 3 and 12 weeks after surgery and postoperative complications and changes in subjective symptoms were noted. The patients were then asked to attend for review every 6 months.

At the final follow-up (mean 58.8 months), a modified Bishop scoring system was used to assess the functional status of the patients (Table 2). Objective motor dysfunction in this score was assessed as grip strength using the Jamar™ hand dynamometer (Sammons Preston, USA). If grip strength as compared to the contralateral side was less than 80% it was classified as abnormal; otherwise it was considered normal. In addition, the patients were asked if they felt that surgery has totally relieved, improved, not changed or worsened their symptoms. Satisfaction from surgery was categorised as complete, partial, minimal or no satisfaction.

RESULTS

Seventeen patients met the inclusion criteria of this study and underwent nerve transposition surgery. Seven patients were excluded from the current study; one had diabetes mellitus, one had concurrent neuropathy at another site on the same ulnar nerve and five others could not attend regularly for follow-up. The ten remaining patients were contacted regularly and returned for free examination and radiographs under a protocol approved by the Ethics Committee of our institution.

All participants were male and the mean age was 36.2 years (range, 20–76 years) at the time of operation. The period between trauma and surgery varied between 1 and 31 years with a mean of 13.2 years. Patients suffered symptoms from 1 to 24 months (mean 8.45 months) before surgery. All patients had a history of elbow trauma resulting in cubitus valgus deformity (mean deformity angle of 20.3°). Seven patients had lateral condyle non-union (four group-I, three group-II non-unions), while three had lateral condyle malunion (Fig 1). Eight patients had limited elbow movement; the mean movement range was 102°. Detailed information on the mechanism of injury, patients’ occupations and the data for each patient is presented in Table 3.

Before operation, all of the patients were suffering from grade III (severe) ulnar neuropathy. While all of the patients complained of subjective and objective motor and also objective sensory symptoms and signs, complaints of sensory symptoms were not as common among the patients (Fig 2). All the patients had a positive Tinel’s sign and elbow flexion test. The motor nerve conduction velocities were more than 25% below the normal reference values for conduction velocity of the ulnar nerve across the elbow (i.e. ≥40 m/s) in all of the patients (Fig 2, Table 4).

At final evaluation, three patients had complete resolution of neuropathy, three showed a decrease in severity of neuropathy and four were unchanged according to McGowan’s grading of severity of ulnar neuropathy (Table 4). All of the patients had some degrees of improvement in both objective and subjective measures (Table 4); Subjective sensory and motor disturbances (i.e. pain, hypaesthesia, paraesthesia and disturbed hand function) were improved or resolved in most of the patients (Fig 2). All of the four patients who had painful ulnar neuropathy became pain-free after operation. Six patients regained the ability to function normally with the hand as before development of disability, three had a significant improvement but still felt clumsy during tasks requiring fine hand movements and one patient reported no improvement in hand function.

Intrinsic muscle atrophy was the sign most resistant to respond to surgery, persisting in four patients without improvement (Fig 2, Table 4). At the final evaluation, six patients regained normal range of motor NCV, three had insignificant reduction in conduction velocity and one patient showed a reduction in motor NCV. The mean motor NCV at the elbow was 38 m/s (Fig 2, Table 4).

According to the modified Bishop score, eight of the ten patients had satisfactory results (i.e. classified as either excellent or good), two had fair results and none had poor results. All patients were at least partially satisfied with surgery. The mean time to return to work after surgery was 6.1 months (range 2–10 months). There were no major complications or recurrences of symptoms in this series and the scar was painless in all cases (Table 5).

DISCUSSION

In this series of ten patients of severe tardy ulnar nerve due to cubitus valgus deformity, anterior transposition of the ulnar nerve led to complete recovery in three patients and improvement in the rest, with no major complications. Sensory symptoms and signs recovered more often than motor symptoms and signs. Although objective measures of motor function failed to show recovery in more than half of the patients, the patients were satisfied with the result of surgery, largely because of relief from disturbing pain and paraesthesia. In addition, most of the patients experienced significant improvement in hand function, despite persistence of muscle atrophy. This finding is consistent with other studies that showed that outcomes were not determined by the degree of muscle weakness and wasting (Beekman et al., 2004; McGowan, 1950). As the literature indicates (Lascar and Laulan, 2000; Macnicol, 1979; Tarczynska et al., 2007), the most important marker of treatment efficacy is the improvement in 2PD distance. Normalisation or improvement in 2PD distance was finding that most strongly predicted relief of symptoms. We found the modified Bishop scoring system to be a useful tool for follow-up of the patients with tardy ulnar nerve palsy.

Prognosis is closely related to the level of pre-operative damage of nerves (Dellon, 1989; Muermans and De Smet, 2002). Severe motor paralysis often requires a long recovery period and recovery may be incomplete. However, marked recovery often is observed in patients with severe symptoms a long time after surgery, and the subjective symptoms and sensory disturbance may improve irrespective of the pre-operative duration (Yamamoto et al., 2006). Two separate meta-analyses (Bartels et al., 1998; Mowlavi et al., 2000) reported 46.5% and 75% satisfactory results respectively for anterior subcutaneous transposition of the ulnar nerve for severe ulnar nerve neuropathy. In addition, some authors believe that the surgical outcome for cubital tunnel syndrome in patients with angular deformity at the elbow is frequently poor (Barrios et al., 1991; Saito et al., 1990) and the recurrence rate can reach 70% (Dellon, 1989). However, the outcome of nerve transposition in the present study is comparable to what has been reported for subcutaneous anterior transposition in severe idiopathic cubital tunnel syndrome in the literature. Neither postoperative modified McGowan’s grade of ulnar neuropathy nor motor NCV findings were reliably related to the final functional outcome of the affected hand or to the improvement of symptoms.

Our study has several limitations. The small number of patients precluded statistical analysis of the data, and seven out of 17 patients who underwent surgery were excluded from study for various reasons.

Our results suggest that anterior subcutaneous transposition is a reliable procedure for severe tardy ulnar nerve palsy secondary to traumatic cubitus valgus deformity. Although the outcome of ulnar nerve transposition is not always satisfactory in severe ulnar neuropathy, useful relief of symptoms can be achieved.