Tendon Transfer for Persistent Radial Nerve Palsy Using Single-Split FCU Technique and Re-Routing of Extensor Pollicis Longus: A Prospective Study of 25 Cases.

PURPOSE: Optimal treatment of persistent radial nerve palsy is controversial. However, most authors agree that tendon transfers lead to satisfactory result in majority of patients. Triple tendon transfer using flexor carpi radialis, pronator teres, and palmaris longus is the most preferred tendon transfer. The aim of this study was to evaluate the results of a split flexor carpi ulnaris (FCU) as a single transfer in such patients and compare our results with other transfers from the available literature.
MATERIALS AND METHODS: A total of 25 patients (20 males and 5 females: mean age: 30.9 years) were selected for FCU split transfer in persistent radial nerve palsy injury from April 2014 to May 2015. All patients were followed up with a mean followup of 1 year. Clinical outcomes were assessed using Bincaz score.
RESULTS: Using Bincaz score, 68% of our patients had good-to-excellent result, while 32% patients had fair and none had bad results. Wrist extension was comparatively less in high radial nerve palsy as compared to low radial nerve palsy patients, but all patients were functionally independent. Power grip was assessed using a jammer dynamometer. All patients had adequate grip strength and good active extension of the wrist and fingers.
CONCLUSION: Single transfer using split FCU can be a preferred alternative in patients of low radial nerve palsy, it can be considered for high radial nerve patients in whom multiple donors are absent due to the nature of injury, for example, brachial plexus injury.

Introduction

Radial nerve injury is one of the common neural injuries of upper extremity. Loss of radial nerve function in the hand creates a significant disability. The patient cannot extend the fingers, wrist, and thumb and has great difficulty in grasping objects.1 It has been proven that in late cases or in cases with irreparable nerve damage tendon transfer leads to acceptable results in majority of patients. There are various types of transfers available, each having its own merits and demerits. The most widely accepted combination is the triple transfer (Jones),2 i.e., pronator teres (PT) to extensor carpi radialis brevis, flexor carpi ulnaris (FCU) to extensor digitorum communis (EDC), and palmaris longus (PL) to extensor pollicis longus (EPL). This transfer has its own demerits of long incisions, prolonged surgery time and difficult training of patients. This was the standard treatment option in our institution until we had difficulty in few cases where we were short of tendon options because of multiple injuries to upper limb and in few brachial plexus injury cases. We studied a technique (Merle d’Aubigne)3 where split FCU tendon transfer was done to EDC and EPL, PL to EPB, and accessory PL. The split FCU tendon transfer has advantages in terms of simplicity, shorter operation time, less morbidity, and less surgical scars. However, this technique has been criticized for not providing adequate abduction along with extension of thumb and causing radial deviation of wrist. To provide adequate thumb radial abduction along with extension, we decided to re-route EPL along the first extensor compartment. There had not been any long term study regarding the efficacy of this transfer in the past 10 years, so we decided to conduct a study on the use of single tendon (split FCU) for transfer to finger and thumb extensors. Our aim was to investigate whether the technique of spilt FCU tendon transfer along with re-routing of EPL improve thumb abduction which would be capable of providing independent thumb and finger extension and wrist stability in power grip and compare these results with proven literature using multiple donor transfer.

Materials and Methods

After taking approval by Institutional Review Board, we conducted a prospective study of split FCU tendon transfer to EDC, extensor indices proprius, and EPL in cases of persistent radial nerve palsy in 25 patients with minimum follow up of 1 year. Informed consent was taken from all patients prior to surgery explaining the pros and cons of surgery. Patients between age of 15 and 45 years with radial nerve palsy of durations more than 9 months with no sign of recovery or early cases with irreparable nerve injuries, or patients with early repair showing no recovery sign till 9 months were included in the study.

Operative procedure

A longitudinal incision is made on ulno-volar aspect of distal forearm, with pisiform as distal land mark and incision extended proximally up to 6 cm distal to medial epicondyle [Figure 1]. FCU tendon was transacted proximal to pisiform and freed proximally up to 6 cm distal to the medial epicondyle. Another longitudinal incision is made over dorsum of distal forearm along the interosseous border of radius and tendons of EDC, extensor digiti minimi (EDM), EPI, and EPL were located and identified. A separate incision of 2 cm was made on dorsum of thumb, proximal to the 1st metacarpophalangeal (MCP) joint, and EPL relocated. Tendon of EPL was cut at its musculo-tendinous junction and delivered out of dorsal incision of thumb. Mobilized FCU was then split in two equal halves [Figure 2] and passed subcutaneously along the ulnar border of forearm to the dorsum, subcutaneous tunnel was made keeping the line of passage as straight as possible. EPL tendon was passed over the 1st extensor compartment subcutaneously, this was done to re-route the EPL tendon so that it can perform the function of extension as well as radial abduction of the thumb. Ulnar part of split FCU was weaved 3 times through each of EDC, EPI, and EDM tendon using Pulvertraft method,4 keeping wrist in 30° dorsiflexion and MCP in neutral extension. In similar fashion, radial part of split FCU wasweaved through re-routed EPL while maintaining thumb in maximum extension and radial abduction. The tension of all the transfers was assessed again by rotating the wrist through full range of motion. With the fingers fully extended with flexion of the wrist and with the fingers flexed into the palm with extension of the wrist, a synchronous tenodesis effect needs to be observed [Figure 3a and b].

Figure 1

The planned incision from pisiform to proximal forearm ulno-volar aspect approximately 5–7 cm distal to medial epicondyle

Figure 2

The flexor carpi ulnaris split into two equal halves

Figure 3

(a) The tenodesis effect of fingers extension with wrist flexion after tendon transfer (b) the tenodesis effect of fingers flexion with wrist extension after tendon transfer

Postoperative management

Our postoperative protocol is shown in Table 1.

Table 1

Post operative rehabilitation protocol

Duration	Therapy	Splinting type
1st 2 weeks	Immobilization of wrist in 30 degrees extension, MP joint in neutral extension , thumb complete extension and radial abduction, and elbow in 900 flexion. Active & passive movements started at DIP &PIP joints	Above elbow slab with distal extension upto MP joints
3rd - 6th week	Long forearm slab converted in below elbow slab , active mobilization at PIP , DIP &elbow joints	Below elbow slab with distal extension upto MP joints
End of 6th week	Slab changed with removable splints	Short cock up - for day timeLong cock up - for night time
7th-8th week	Re education of transferred tendonActive wrist flexion (FCU)- Initiate digital extensionActive wrist flexion (FCU)-Initiate thumb extension & radial abductionTen repetition of each exercise initially 3 to 4 times a day gradually increased 6 to 8 times a day	Short cock up - for day timeLong cock up - for night time
9th -10th week	Re education of transferred tendonIf power of transferred tendon is MRC grade II then allow light activities like taking lid off large and small containers.Picking up cottons balls, manipulating checkers at this time	Short cock up - for day timeLong cock up - for night time
11th -12th week	Re education of transferred tendonStrengthening exercises started as soon as power of transferred tendon achieved of MRC grade 3. These include carom board playing, pushing a container filled with grains or dust with wristAvoid strenuous activities as screwing and descrewing tight bolt & lidAllow daily activities as eating, grasping the lid and small things	Short cock up splint for day use and long cock up splint for night. Short cock up may be discontinued if wrist power is of grade 3
13th -14th week	Re education of transferred tendonStrengthening exercises As soon as MRC grade 4 near about 13 to 14 weeks post operatively we will allow using hand for usual function but avoiding strenuous activities for next 4 to 6 weeks	Discontinue long cock up splint over a period of 2 to 3 week

Final assessment

In the final assessment, active range of motion of wrist and MCP was measured. First web space opening was measured using goniometer. Power grip was measured using jammer dynamometer. Radial deviation of the wrist was measured during testing of power grip. Final results were calculated using Bincaz score,5 Kapandji score,6 and DASH7 score and patients were asked regarding any changes in job or leisure activity relating to the injury or after transfer surgery.

Results

Twenty males and five females with a mean age of 30.9 years (range 15–45 years) [Table 2] were included in the study. Most of the patients (56%) in the study were manual worker followed by students (28%). The most common mode of injury [Table 3] was road traffic accidents (12 cases, 48%) followed by direct nerve transaction by glass cut and tin shade injury (8 cases, 32%) and iatrogenic injury (4 cases, 16%), of which 3 cases were in which PIN was injured during fixation of fracture of proximal radius and 1 case occurred during fixation of Holstein–Lewis fracture of humerus. In these cases also, recovery was not noticed at 9-month duration. In our study, 12 cases were of high radial nerve palsy, i.e., in which wrist extensors were also involved in addition to finger extensors and 13 cases were of low radial nerve palsy in which wrist extensors were spared. There was no case of very high radial nerve palsy. All the patients we operated had supple joints and M5 grade power of donor muscle. The mean postoperative followup was 1 year (range 12–18 months). One year after surgery, 60% of patients had [Table 4] wrist flexion in the range of 20°–30° and 28% had range less than 20° and mean flexion of 24° (16°–35°). Similarly, flexion without gripping ranged from 22° to 40° with a mean of 33°. Based on Bincaz et al. criteria,5 44% of our patients had good wrist extension, i.e., more than 29°, 56% of the patients had fair wrist extension, i.e. between 0° and 29° with mean extension of 26° (15°–40°). Most of our patients showed first web opening >39° (76%), 24% of our patients showed first web space opening <39° with mean of 44° (36°–56°). Nearly 68% of patients had good-to-excellent satisfaction, in rest 32% of patients satisfaction level was fair. Mean Kapandji score6 was 7.8 (7–10) We compared the overall result [Table 5] according to Bincaz et al. score5 and found that 68% of our patients had good-to-excellent result, rest 32% patients had fair result, none of the patients had poor result. Most of the patients reported that there was only minor-to-moderate effect on their activities of daily living (ADL) (92%). Nearly 8% of patients reported that they had a disturbing experience on their ADL after transfers. The most common complaint was dropping of wrist while gripping an object. Most of these patients were noncompliant to postoperative regimen. Longer rehabilitation under supervision was recommended for these patients. Most of the patients (88%) recorded a grip strength of >9 kg, rest 12% patients recorded grip strength <9 kg with mean grip strength of all being 17.3 kg. Two patients had superficial infection which was treated with intravenous (IV) antibiotics. Beside this, we had no other complication in our series. The patient responses to DASH questionnaire resulted in mean total score of 20 ± 10. Posttendon transfer, the DASH score reduced to 12 ± 5. Twenty out of the 25 patients returned to their preinjury work level. Followups are shown in Figures 4-7.

Table 2

Age incidence

Age group	No of patients	Percentage
15-25	6	24%
26-35	16	64%
36-45	3	12%
Total	25	100%

Table 3

Mode of injury

Mode of injury	No of patients	Percentage
RTA	12	48%
Glass cut	5	20%5
Tin shade	3	12%
Iatrogenic	4	16%
Slip and fall	1	4%
Total	25	100%

Table 4

Range of movements

Wrist Flexion with fisting	No of patients	Wrist flexion without fisting	No of patients	Active wrist extension	No of patients
Less than 20 degree	7	Less than 0 degree	0	Less than 0 degree	0
21 to 30 degree	15	0 to 30 degree	8	0 to 29 degree	14
More than 30 degree	3	30 to 40degree	17	More than 29 degree	11
Total	25		25		25

Table 5

Final results based on bincaz score

Bincaz score	No of patients	Percentage
8 or more than 8 (Excellent)	5	20%
6 or 7 (Good)	12	48%
4 or 5 (Fair)	8	32%
3 or less than 3 (Bad)	0	0%
Total	25	100%

Figure 4

Patient with radial nerve palsy of the right side

Figure 7

Wrist flexion with fisting

The final postoperative results of finger extension without fisting

Wrist extension with fisting after 1 year of followup

Discussion

Tendon transfer is considered a standard treatment in case of persistent radial nerve palsy. There are multitude of options available for tendon transfer with comparable results. The major controversy in the tendon transfer for radial nerve has been between the use of FCU or flexor carpi radialis (FCR) for providing digital extension and use of single or multiple transfers to provide extension and abduction of thumb. The major problem with FCU transfer has been its inability to gain full abduction of thumb along with extension.8 To solve the first issue, we divided EPL from its musculo-tendinous junction and took it out from its third compartment and re-routed it along the first extensor compartment. By doing so, the line of pull of transfer allowed thumb abduction along with thumb extension. All the patients in our series were able to extend the fingers, not only in wrist flexion, but also in the neutral wrist position and, even, when the wrist was in extension. They were also able to flex their fingers to make a full fist. This indicates an active and dynamic biomechanical result of this transfer which cannot be explained by a simple tenodesis effect. In our series, all patients had normal power (M5 on MRC grading) of donor muscles. We never used a recovering muscle as a donor for any of our transfers. Wrist flexion is of utter importance in tendon transfer cases because of the fact it shows the tightness with which donor flexor tendon is sutured with the finger extensor, more the tightness less will be release of extensor tendon during power grip, which ultimately leads to weakened grip strength. The mean wrist flexion with fisting in our study was 24° and without fisting flexion in our study was 33° which is comparable with other studies (Ropras and Bincaz et al.5). We used a stronger wrist flexor as a donor in form of FCU which leads to comparatively lesser wrist flexion postoperatively in contrast to Ropras who used FCR as a donor. By this observation, we can say there is on average 10° of greater wrist flexion where FCR is used as donor as compared to transfers where FCU is used as a donor. However, the studies by Kruft et al.3 have shown that 20° of wrist flexion is adequate for ADL which we were able to attain in all of our cases. The mean active extension at wrist in our study was 26°. Patients with posterior interosseous nerve (PIN) palsy had greater than 29° extension in 11 out of 13 patients as compared to patients with high radial nerve palsy where all patients had less than 29° wrist extension. This finding was not consistent with findings of Ropras (JHS 2006) and Bincaz et al.5 In their series, active extension at wrist was 38°, which was much greater than our study. This variation is attributed to the fact that we never used any separate donor for wrist extension in contrast to Ropras (JHS 2006) and Bincaz et al.5 Both used PT as a separate donor for wrist extension. As previously mentioned by Kruft et al.,3 20° of wrist flexion/extension is adequate for ADL which was attained in all of our cases. Mean abduction of the thumb was 43° and opposition was 7.8 points according to the Kapandji scale,6 which was comparable to Bincaz et al.5 and Ropras. In a similar study using single FCU transfer for radial nerve palsy cases, Gousheh and Arasteh,10 have reported 38° of mean radial abduction of the thumb. We reported greater radial abduction using same donor. This may be attributed to the fact that we used a different technique for passage of EPL tendon. Instead of taking the routine route, we re–routed the tendon over the first extensor compartment, thus allowing for greater radial abduction. EPL is extensor and adductor of thumb metacarpal. When re-routed radially from Lister's tubercle in the line of first extensor compartment and passing through anatomical snuff box, EPL becomes extensor and radial abductor of thumb. (Scuderi 1949)9. Based on these findings, we strongly recommend rerouting the passage of EPL, and this method of transfer helps attain a near-normal thumb radial abduction. All the patients with low radial nerve palsy had some degree of radial deviation during power gripping with mean deviation of 14° in our cases due to the presence of strong dorsal radial deviators and absent dorsal ulnar deviators. In this scenario, taking the only ulnar deviator, i.e., FCU causes radial deviation which was passively correctable. However, this radial deviation did not hamper ADL of any patient. Grip strength depends on the ability to stabilize the wrist in extension. Mean grip strength measured using dynamometer was 17.3 kg which was well above the functional range, i.e., >9 kg in all our cases. Using the Bincaz et al.5 assessment scale, out of 25 patients, 17 had good-to-excellent and 8 fair results, which is consistent with the findings of Ropras. Almost 80% of our patients were able to return to their previous jobs. In our study, we recorded DASH7 score preoperative ranging from 7 to 28 which later reduced to 5 to 15. The DASH score gathered in our study are all positive and indicate only little limitation of the upper extremity in day-to-day life activities. Every surgical procedure has its own complications. In the present series, two of the patients had superficial infection which was treated with IV antibiotic and five other patients had some cosmetic-related complaint such as abnormally protuberance of belly of FCU on ulnar border of forearm. Our study showed that split FCU transfer is a reliable option in patients with persistent radial nerve palsy. Transfer of single FCU has some advantages, including simplicity, shorter operation time, less morbidity due to transfer of single tendon, and not least, less surgical scar, which can be important in some patients, especially females. Though all the patients were functionally independent in our series, still we consider our results to be better in low radial nerve palsies in which wrist extensors were spared. In respect to use of one tendon instead of three, this transfer may have particular value in war victims, who often do not have single injuries to the limb or patients with brachial plexus injuries with limited options for transfer.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.