Pages 102 - 114 Volume 93, Issue 2
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Correction of ulnar claw hand – A comparative study of extensor carpi radialis longus (ECRL) and flexor digitorum superficialis (FDS) as the motor unit of choice

Leprosy is a chronic infectious disease caused by M. leprae, with peripheral neuropathy as its most common manifestation. Deformity of the hand is particularly debilitating and the ulnar claw hand is the most common presentation. There are various surgical options available for correcting clawing in Hansen’s disease. In the present study we have tried to identify patient-related factors favouring either Extensor Carpi Radialis Longus (ECRL) or Flexor Digitorum Superficialis (FDS) as the motor unit of choice.

Method

A comparative study of ECRL (Brand Procedure) and FDS (Stiles–Bunnel) motor tendon transfer in the ulnar claw of hand was carried out. Correction of clawing of fingers was done in 60 ulnar claw hands using transfer of motor units ECRL and FDS. The Z deformity was corrected by 1∕2 FPL to EPL transfer. 12 cases were lost to follow up over the course of 5 years, so 48 cases were followed for up to 2 years, for various activities of daily life and routine work.

Conclusion

Both the transfers gave equivalent results. No morbid deformity was seen in ECRL transfer except the scar on the donor thigh. FDS transfer is the best reconstructive tendon transfer procedure for correction of ulnar claw hand in manual labourers. For white-collar workers, ECRL transfer should be the choice.

Cite this article
Imran Sajid, Sabeel Ahmad;
Correction of ulnar claw hand – A comparative study of extensor carpi radialis longus (ECRL) and flexor digitorum superficialis (FDS) as the motor unit of choice; Leprosy Review; 2022; 93; 2; 102-114; DOI: 10.47276/lr.93.2.102
LEPROSY
Leprosy Review
2162-8807
British Leprosy Relief Association
Colchester, UK
Introduction
Ulnar and median nerve involvement is common in leprosy. The ulnar claw hand is the commonest (79%) among the hand deformities. Ulnar nerve involvement leads to paralysis of ulnar supplied muscles leading to clawing of predominantly the little and ring fingers. In a typical claw hand only the ring and little fingers are involved while the middle and index fingers still have power in the lumbrical muscles (supplied by the median nerve) which can straighten the fingers and bring them to the lumbrical plus position.
Ulnar nerve palsy affects the functional ability of hand. In claw hand deformity the hand is not able to grasp large objects as it cannot adopt the initial position of flexion of the metacarpo-phalangeal joint (MCP) and extension of inter-phalangeal (IP) joints. Grip strength is almost always diminished and key pinch is also lost.
To restore the grasp function, the aim is to recover the lost function by substituting an additional motor unit to the paralyzed lumbricals and interosseous muscles. Tendon transfers are based on the concept that nothing new is created but functional parts are rearranged into the best possible working combination. This is done by relocating a tendon from a functioning muscle to replace an injured or non-functional muscle-tendon unit.1 For the ulnar claw hand, the point of debate arises as to whether to give active motor support to ring and little fingers only, or to all four fingers. The consensus amongst hand surgeons is to give support to all four fingers for better coordination.2
Bouvier’s test is done to differentiate between simple and complex clawing. This involves passively correcting the MCPJ hyper-extension and checking for improved IPJ extension. If the patient’s flexed IPJ posture improves, then Bouvier’s test is positive, and clawing is defined as simple. If the IPJ’s remain flexed, then Bouvier’s test is negative, and the clawing is defined as complex.3
Tendon Transfer Procedures for claw correction
Stiles-Bunnel FDS transfer
The FDS tendon is transected distal to the A2 pulley and split into four slips. Each slip of the FDS tendon is tunneled along the lumbrical canal then looped around the lateral bands. The transfer is tensioned and secured with the wrist in neutral position and the MCPJ at 45° of flexion.4
Brand procedure (ECRL with 4-tail tendon transfer)
A transverse incision at the dorsal base of the index metacarpal is used to expose the insertion of the ECRL tendon. A palmaris longus tendon graft is harvested and secured to the ECRL tendon end, the two tendon graft ends are split to create four tendon ends (depending upon the number of fingers to be corrected) and sutured to the lateral band.5 In our study we used fascia lata graft in place of palmaris longus tendon (as described by Dr. Brand originally).
Methods
Fifty-four patients were enrolled in the study and underwent corrective surgery at the Department of Orthopaedics FHMC Agra and O.P.D National Jalma Institute Tajganj Agra, between November 2015 and April 2020. Approval of the ethical committee (ref no : FHMC/IEC/15/19) and written informed consent from all the subjects were obtained. All patients were smear negative and had taken MDT for 6 to 12 months.
Ages ranged from 15 to 50 years and the duration of the claw hand was between 9 and 24 months. Six patients were lost to follow up, leading to only 48 claw hands being included in the study. Patients were followed up every month up to 6 months than 3-monthly and 6-monthly up to 2 years.
Of the 48 claw hand patients in regular follow up, 12 were female and 36 were male. 26 were white-collar workers, of whom 14 had FDS as the motor unit while 12 had ECRL as the motor unit. 22 patients were manual labourers, of whom 11 had FDS as the motor unit while the remaining 11 had ECRL as the motor unit. All hands were mobile and supple. Forty-eight hours after surgery, physiotherapy was started in both groups.
Group A (24 hands) – ECRL transfer (Brand procedure)
Group B (24 hands) – FDS transfer (Stiles-Bunnel procedure)
Inclusion criteria
Pure ulnar claw patients (15–50 years of age).
Smear negative cases.
Completed MDT therapy.
Mobile, supple hand joints (PIP/MCP) without any associated skin problems.
Patients with positive Bouvier’s test (i.e. simple claw).
Motor unit
Extensor Carpi Radialis Longus (ECRL) power 5/5 on MRC Grade.
Flexor Digitorum Superficialis (FDS) power 5/5 on MRC Grade.
Pre-operative preparation
All patients were started on isolated motor unit strengthening exercises one week before surgery. Oil massage and wax therapy were given to make the hands supple.
Surgical technique
Brand procedure (ECRL with 4-tail tendon transfer)
Step 1: Recovery of ECRL Tendon.
The ECRL muscle is identified in the ‘snuff box’ at the wrist at the base of the 2nd metacarpal bone, at its insertion (Figure 1). The tendon is exposed and lifted by hook and clamped around a curved artery forceps, and ligated at its insertion.
Figure 1.
Identification of ECRL.
A second incision is made over the greatest convexity of the radial border of forearm about 8 cm above the radial styloid process (Figure 2). The synovial sheath of the tendon is cut and the ECRL tendon identified by stretching the ligated end and withdrawing at this level in the forearm.
Figure 2.
Isolation of ECRL Tendon.
As the ECRL muscle is short and will not reach the extensor expression (lateral bands) at the finger creases, it needs elongation by a graft. Most commonly used grafts for this are Palmaris Longus tendon and Fascia lata graft. We chose the Fascia lata graft from the thigh because we did not want to sacrifice a viable motor unit of the hand – palmaris muscle tendon.
Step 2: Harvesting Facia lata graft and anastomosis with ECRL tendon.
A 2 cm transverse incision is made at the junction of middle and distal quarter of thigh. The deep facia and fat is dissected and a 15–20 cm Facia lata graft is harvested (Figure 3). The skin is closed by 3′0′ silk suture. Initially, for a few cases we harvested the Fascia lata graft using a tendon stripper from two small incisions (proximal and distal). But we realized that often there was an issue of muscle herniating through the Fascia lata defect causing morbidity to the patient for quite some time; also it was noted that with the blind use of the tendon stripper there was at times unequal thickness of graft or a torn graft. Hence we now follow a protocol of open harvesting of the Fascia lata graft. The graft is cleaned of the attached fat and tissue. The graft is laid down on the mop with its cut end directed proximally. A boat shaped hole is made in the ECRL tendon and the Facia lata graft is passed through in such a way that it overlaps about 2 cm with the ECRL tendon . The stay sutures are placed in the Facia and the ECRL tendon. Now the anastomosis is completed by suturing of facia with the ECRL tendon.
Figure 3.
Harvesting facia lata.
Step 3: Tunneling of substituted motor tendon units in the palm.
A 2.5 cm incision parallel to the proximal crease in the hollow of the palm is made, down to the level of the flexor tendon sheath. All the deep facia and fat is cleaned and the flexor tendon sheath is exposed. Now the tunneller is passed below the flexor retinaculum and brought up to the incision where the ECRL tendon is exposed. The tendon is held in the tip of the tunneller and tunnelled below the flexor retinaculum up to middle of the palmar incision (Figure 4). The tendon is divided in to four slips/tails and is ready to tunnelled up to the lateral band expansion (Step B).
Figure 4.
Tunnelling of substituted motor tendon units.
Stiles-Bunnel procedure (FDS transfer)
Step A : Recovery of FDS Tendon.
The FDS tendon is inserted at the base of middle phalanx in two slips. A small incision is made in the ring finger at the palmar side (Figure 5a–c). Both the slips are identified and held in artery forceps. After confirming, by stretching the FDS tendon, it is ligated at its insertion point and divided into two slips and withdrawn at mid palm.
Figure 5.
(a) Incision site at palm. (b) Isolation of FDS digit at proximal phalanx site of ring finger. (c) Retrieving FDS digit at the palm.
Step B: Tunnelling of four slips into finger (lateral expansion).
Now tunnelling of four slips of both the donor tendons (ECRL/FDS) is done in the same way. These four slips are laid down on wet gauze in the same sequence in which they were divided from the parent tendon (Figure 6). A small incision is made at the level of the MCP joint and finger creases. A small tendon tunneller is passed through the neurovascular canal of each finger along the lateral band expansion. This may be achieved by flexing the finger at the MCP joint at 30° on a hand splint. The tip of the tunneller should slide smoothly through the neurovascular canal along the lumbricals. The tip reaches up to palmar incision and each slip is picked up and tunnelled up to the extensor expansion level (Figure 7). We preformed the tunnelling of slips from index to little and ring and lastly in middle finger.
Figure 6.
Dividing the FDS digit at palm into 4 slips.
Figure 7.
Tunnelling the 4 slips of FDS and suturing them to the lateral expansion.
Adjustment of tension in all four fingers
The hand is kept in a hand splint where all four fingers and wrist are at 30° flexion and the MCP joints are in 60° flexion. It is necessary that all four fingers slips should be sutured at equal tension while the hand is in the neutral position (Figure 8). Here we sutured first the index finger slip. The slip was pulled in the line of the finger to check the smooth gliding in the palm and then sutured to the lateral band (dorsal expansion) slip without putting any tension. After that little finger slip was sutured in the same way by giving an axial pull of 5–7 mm over the slip. Now at last the middle and ring finger slips were sutured under minimum tension. If any inadvertent extra tension is given to these last two slips, the index and ring fingers will develop slack. All four slips are sutured with the extensor expression with 4′0′ silk sutures. All incisions of palm, forearm and fingers are closed by 2′0′ silk.
Figure 8.
Position of hand while suturing the FDS slips to lateral expansion.
All exposed incisions are dressed and padded with cotton and a dorsal splint in 90° palmar flexion is placed up to the forearm. The fingers are kept in the lumbrical plus position and the thumb is kept free in abduction (Figure 9).
Figure 9.
Post-operative position of hand.
Post-operative protocol
Both groups were maintained on a similar post-operative rehabilitative protocol. We started early mobilization after 48 h of surgery providing the patients had no pain or oedema over the operated fingers. A few patients had post-operative oedema, which subsided by 72–96 h post-operatively, when they started physiotherapy.
After 48 h the patients started with palmar flexion of wrist with plaster support on the dorsum which was gradually converted to 75° from 90°. This means the patient can also extend and flex his fingers by 15° after 48 h.
On the 4th day the plaster cast is converted to 60° and the patient is allowed to do flexion and extension up 60°. Every 2nd day the extension and flexion are increased by 15°. At the end of the 8th day the patient is able to flex and extend the fingers up to the full range of motion. Fist formation is started from the 9th day and completed by the 12th day (Figure 10). Full range of motion is generally achieved the 12th to 15th post-operative day, and the patient has also started practising the grasp function and picking up small objects like seeds and grains; also practising grasping and holding big objects like a cup or glass is started, and complete function of the hand is achieved by 3 weeks. Clinical images were taken at 6th week for FDS and ECRL transfer (Figures 11 and 13).
Figure 10.
Post-operative protocol for hand.
Figure 11.
6 weeks follow-up for FDS Transfer.
Figure 12.
2 year follow-up for FDS Transfer.
Figure 13.
6 weeks follow-up for ECRL Transfer.
Figure 14.
2 year follow-up for ECRL Transfer.
The pinch action is also weak in the pure ulnar nerve palsy so while picking of objects by index finger and thumb, a Z deformity develops due to weakness of the intrinsic muscles of the thumb. We did 1∕2 flexor pollicis longus transfer to extensor pollicis longus tendon at DCP joint to give functional support to the intrinsic muscles of thumb.
The results were compared on the basis of the functional correction of the hand and use of the hand in activities of daily living such as:
(1)
Grasping of big objects like glass, tumbler.
(2)
Grasping of small objects like button, pen.
(3)
Picking up small objects, like grains, small stones.
(4)
Use of the hand in activities like wearing clothes, combing, bathing, driving, typing, eating food.
At the final follow-up of 2 years (Figures 12 and 14), patients were interviewed and physical examination was performed.  Patients were asked about overall satisfaction with the operation (yes/no), whether they has been able to return to their job, and finally when they had been able to use the limb usefully for daily activities (the time to maximum recovery). On physical examination, the related ranges of motion were recorded. Functional outcome was divided into excellent, good, fair, and poor based on the ranges of motions of fingers, thumb and wrist.
Results
The study included 48 patients. Individual results were calculated for the activities of daily living and then their mean was derived and a final result was derived. The overall outcome was as follows: ‘Good’ results were obtained in 77% patients for the ECRL group and 76% for the FDS group; ‘fair’ result was the outcome in 15% patients for the ECRL group and 17% for the FDS group and ‘poor’ results was the outcome in 7% patients for the ECRL group and 7% for the FDS group (Tables 1 and 2).
Table 1
Analysis of results
ECRL/FDSGoodFairPoor
Cosmetic corrections hand 24/2417/155/4 3/4
Grasping of big objects 24/2417/185/6 2/0
Grasping of small objects 24/2418/193/4 2/2
Picking of small objects 24/2420/192/3 2/2
Use of hand in daily life 24/2421/203/4 0/0
Table 2
Mean aggregate of results of both groups
ResultTotal (48)
Mean of all daily use activityECRL FDS
Good77.5%75.8%
Fair15.3%17.5%
Poor 7.2% 6.7%
Table 3
Mean aggregate power of pinch
Normal Pinch Power (Average) Claw HandPost-operative ECRLPost-operative FDS
8–9 kg/Sq1.5–2.0 kg/Sq 4.5 kg 6 kg/Sq
With 48 claw hands in the study group, good cosmetic correction was achieved in 67% (32/48) of patients. All these cases had surgery quite early in the disease progression, so atrophy of fat pad and hypothenar muscles had not developed.
33% (16/48) had long-standing disease. The fat over the dorsum of hand and hypothenar muscles was completely atrophied and the hand appeared very thin. After correction and aggressive physiotherapy there was improvement in the bulk of hypothenar muscles in 9 claw hands (18%). These cases had fair cosmetic correction.
14% (7/48) cases did not show any regrowth of fat over the dorsum and hypothenar muscles and the hand was as thin as it was pre-operatively. These patients were categorized as poor cosmetic results.
The other daily life routine work like grasping of large and small objects, picking up small objects like grains or papers, wearing cloths, handling of buttons, brushing of teeth, and breaking of bread slices were achieved in 75–80% of cases in both the groups and recorded as good results. 20% cases had fairly good results.
Post-operative pinch power as measured by a pinch strength dynamometer was slightly better at three months period for FDS as compared to ECRL group (Table 3), though comparative as two-year period.
Discussion
Deformities in Hansen’s disease are the consequence of impairments of nerve function. Many leprosy patients develop ulnar nerve paralysis alone, or combined paralysis of ulnar and median nerves. The paralysis of ulnar nerve results in ulnar or partial claw hand, involving the fingers mainly, while the paralysis of ulnar and median nerves gives rise to total claw-hand involving the thumb as well as the fingers.6
Clawing is defined as hyperextension at metacarpophalangeal joint and flexion of interphalangeal joint. Clawing of fingers not only weakens the hand, but also leads to instability, incoordination, imbalance and synergism.7
Claw-finger and Z-thumb deformities are common deformities following ulnar paralysis in Hansen’s disease patients. Correction of claw hands in these patients is achieved by transferring a motor tendon, such as the tendons of Flexor Digitorum Superficialis (FDS), Palmaris Longus, Extensor Carpi Radialis Longus (ECRL) or extensor indices to any one of four insertion sites in the fingers.8 These insertion sites are the lateral band of the dorsal extensor expansion,9,10 the proximal phalanx,11 the proximal annular pulleys of the flexor sheath12 and the interosseous tendons.13,14
The aim of the surgical procedures is to prevent hyper-extension at the metacarpophalangeal joint and to initiate flexion of the proximal phalanx as in normal hands and also to reinforce the extensor power to extend the interphalangeal joints as in dynamic procedures.
ECRL transfer used for correction of clawing of fingers needs good and extensive postoperative re-education and training to retrain the transferred muscle.
FDS transfer patients observed that they had more power during the holding of the objects. The manual workers felt more comfortable with manual work like digging ground, lifting bricks, etc., in comparison to ECRL transfer patients.
For routine household work and office desk jobs like computer usage or typing, both the groups were equally comfortable but some female patients felt more comfortable in kitchen work after the FDS transfer, due to better pinch.
The long-term follow up results of cases in both groups were more or less same.
A weakness in our study is the subjective nature of assessments of patients’ responses. We have taken the patients’ responses and with that evaluated the final outcome. At times due to difference in patients’ education level and comprehension status, their responses might have brought an acquiescence bias. We have tried to solve this by averaging the responses so as to dilute the bias.
Conclusion
The ECRL and FDS were used as motor units to substitute the paralyzed muscles in claw hand correction. The ECRL transfer patients were happier in fine work like typing and handling of papers, while the FDS transfer patients were more comfortable in heavy manual work for the initial 3–9 months period. Long-term results for both were comparable. This study shows that ECRL transfer is more suitable for office going persons while the FDS transfer is more suitable in manual workers.
The overall results of surgery depend on correct selection of the transferring motor unit, the patient’s age, the duration of clawing, pre and post-operative physiotherapy and finally the compliance of the patient for the post-operative protocol.
References
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