Assessment of Results of Opponensplasty

INTRODUCTION

Several procedures have been described for the restoration of thumb opposition (Beine et al., 1989; Sane et al., 1997). Objective assessment of these is often poorly detailed, although scoring systems have been proposed by Palande (1975), Anderson et al. (1991) and most recently Mehta and Malaviya (1996). That of Palande is too complex for widespread use and the scoring system of Anderson et al. (1991) is function-based but difficult to interpret. Mehta and Malaviya’s system is fairly simple and covers a variety of useful thumb functions. One variable that is not included in most of these assessments is the patient’s opinion about the result of the operation. Thus, although the operation may appear excellent on objective testing, it may fail to fulfill the needs of the patient and thus should not be classified as a success. Likewise an operation may not score well on objective measurement but may be quite adequate for the patient’s needs.

This study was carried out in order to assess the results of opponensplasty at our institution, and to compare objective hand evaluations with the patient’s subjective evaluation of the functional improvement.

PATIENTS AND METHODS

All patients who had undergone reconstructive surgery for opponens replacement at Anandaban Hospital between January 1987 and December 1997 were retrospectively studied. One hundred and seventy operations were done, but 14 records were incomplete or missing. Adequate records were found on 156 operations on 137 hands of 115 patients. In all cases the aetiology was leprosy. There were 98 men (85%) and 17 women (15%). Fifty-four per cent were farmers, 20% were in business, 10% were students, 12% were in various other areas of work, and only 4% were professionals or in government service. The average age was 30, and the mean follow-up was 20 (range, 1–108) months.

The types of operation are summarized in Table 1. Forty-two per cent had an additional procedure carried out at the same time as the opponensplasty, usually a “lasso” procedure or a thumb web plasty. The “lasso” procedure (flexor digitorum superficialis (FDS) to A2 pulley transfer) was done to correct the clawing caused by ulnar nerve palsy and the web plasty was performed if the pre-operative thumb web angle was less than 40° (following physiotherapy). In almost all cases a ring finger FDS (occasionally the middle finger FDS) transfer was performed, using Guyon’s canal as the pulley (Fritschi, 1984). After dividing the FDS near its insertion through either a palmar or lateral incision (Fig 1), it is brought out just proximal to the wrist. It is then tunnelled up Guyon’s canal and across the palm to a small incision on the radial border of the proximal phalanx of the thumb just distal to the metacarpophalangeal joint. One slip is routed around the dorsal surface of the proximal phalanx and is sutured to the adductor pollicis close to its insertion. The other slip is sutured to the extensor pollicis longus at the interphalangeal joint (Fig 2). The suturing is done with the wrist and thumb metacarpophalageal joint each in 30° of flexion with the interphalangeal joint in full extension, and the thumb in full abduction and internal rotation with 1 cm tension on the adductor pollicis slip and no tension on the extensor pollicis longus slip. Postoperative casting is done with the thumb in full opposition. We remove the cast and begin physiotherapy 3 weeks postoperatively.

Eight patients with fixed flexion deformities of the interphalangeal joint underwent flexor pollicis longus transfer with interphalangeal joint fusion as described by Davis and Barton (1999). The flexor pollicis longus was withdrawn in the wrist, passed through the carpal tunnel and around the ulnar border of the palmar fascia (Thompson’s pulley), and then sutured to the insertion of the superficial head of flexor pollicis brevis.

In 120 of these 156 operations outcome was measured by objective and subjective measures. Outcome was assessed by recording the most ulnar finger with which the thumb could achieve a pulp to pulp pinch grip with its interphalangeal joint extended (pulp-to-pulp finger pinch). If there was no contact the thumb scored zero, the index scored 1, the middle scored 2, the ring scored 3 and the little finger scored 4. These values are expressed as a median and range. The “opponens gap”, representing the gap (mm) between the thumb and little finger metacarpophalangeal joints in full active opposition, was also measured and reported as the median and range. Finally, the patient assessed their satisfaction with the operation as good, fair or poor. They based this assessment simply on the extent to which the operation assisted them when carrying out their individual activities of daily living and whether the result of the operation matched their pre-operative expectations. Marked increase in the ability to use the hand gave a good rating, moderate improvement gave a fair rating, and no improvement or worsening gave a poor rating. It was felt that to define this subjective rating more tightly would reduce the subjective value of the score.

RESULTS

The opponens gap was reduced from a median of 50 (range, 30–90) mm to 40 (range, 20–65) mm, and pulp-to-pulp finger pinch increased from a median of 0 (range, 0–4) to 3 (range, 0–4). This indicates that pre-operatively the patients could usually achieve no pulp-to-pulp finger pinch while postoperatively they could usually oppose to the ring finger. This represents 89% good or excellent results based on the scoring system of Sundararaj. Ninety-four per cent of the 120 patients who underwent objective and subjective assessments reported good or fair satisfaction. Of note is that 55% could not achieve any pinch grip pre-operatively compared to 11% postoperatively.

The objective measurements (opponens gap and pulp-to-pulp finger pinch) were compared with the subjective measurements of patient satisfaction (Table 2). This revealed only moderate correlation.

The results were also broken down by age (Table 3), based on the hypothesis that in Nepal elderly patients may have greater trouble learning to use the tendon transfer.

However, older patients scored as well as younger patients on both the objective and subjective measurements. Also, those who underwent concomitant hand procedures had similar results to those having only an opponens transfer (Table 4).

Those having opponens revisions were separately analysed. Nineteen repeat operations were done for poor function of the original procedure. In most cases this involved tightening or repositioning the original transferred tendon, while five had an FPL opponensplasty. These procedures were done on an average of 32 (range, 4–81) months after the original procedure. The opponens gap from the repeat procedure was only reduced from 42 to 41 mm although pulp-to-pulp finger pinch increased from 2 (range, 0–4) to 3 (range, 0–4). Good patient satisfaction was reported by 10 of the 19 patients.

Overall there were seven early complications and 16 late complications (Table 5).

DISCUSSION

Multiple procedures have been described for replacement of the opponens action of the paralysed thenar muscles. Success rates of between 75% and 100% are generally reported. This study 89% achieved good or excellent results using the scoring system of Anderson (Anderson et al., 1991), which is similar to the 85% reported by Anderson et al. (1992), the 90% by Patond et al. (1999) and the 94% by Palande (1975). Comparison with other authors is difficult due to the use of different scoring systems.

Many of our patients underwent a concomitant lasso procedure using flexor digitorum superficialis. Concomitant intrinsic/opponens replacement was first described by Shaw (1984) with good results in five patients. Our study showed no disadvantage to combining the two procedures and there were no problems with re-education during physiotherapy. Indeed by doing both procedures at once the period of immobilization and the hospital stay were reduced. It also hastened reintegration into the community, another goal of leprosy treatment.

An age of 50 years was arbitrarily used to compare older and younger patients. Many authors do not record the age of the patients, and very few patients over the age of 40 years have been assessed after opponensplasty (Anderson et al., 1991 , 1992; Palande 1975; Srinivasan 1982). Our results suggest that older patients have as good results as younger patients and thus age should not be a deterrent to opponens surgery.

There is a natural and reasonable desire in medicine to describe results in objective measurements. This is necessary in order to quantify results of treatments, follow patients’ progress and compare with different treatments. However, one should not forget the patients’ perception of how the operation has benefited him or her. This perception in reconstructive surgery is arguably the ultimate measure of success. While unrealistic expectations of the patient may lead to poor results by this measure, we found this uncommon. Although Mehta and Malaviya (1996) state that a subjective evaluation is utilized in their institute’s evaluation, they do not further elaborate. Patond et al. (1999) reported that only 57% of patients reported improvement in function after an extensor indices proprius transfer compared with 75% of patients after an FDS transfer, although objectively the two procedures scored similarly. Our patients reported a high degree of satisfaction with the FDS opponens replacement, and thus this is a satisfactory technique for the Nepali/North Indian population, and meets their perceived requirements. However, patient satisfaction did not correlate closely with our objective measurement of the outcome, indicating that objective measurements alone do not fully assess the success of an opponensplasty from the patient’s perspective. In this study the question regarding patient satisfaction was very generalized. We could instead have asked the patients to rate their change in ability to do specific tasks of daily living before and after the operation, and the use of an outcome measure such as the DASH (Disabilities of the Arm, Shoulder and Hand) (Beaton et al., 2001) pre- and postoperatively might have been appropriate. However, most of the questions asked in the DASH are irrelevant to a rural Asian population and the authors are unaware of any outcome measure which has been validated in this population.

In conclusion, both by objective and subjective measurements, the opponensplasty in our hands has a high degree of success, irrespective of age. A “lasso” procedure can be safely added to an opponensplasty without adversely affecting results. Finally, a subjective score of patients’ satisfaction should be a part of all assessments following tendon transfers.