The Hand Unit, University of Cape Town and Red Cross War Memorial Children's Hospital, Cape. Town, South Africa. Key words: Primary repair; Flexor tendon.
Ann R Coll Surg Engl 1995; 77: 135-137
Flexor pollicis longus tendon injuries in children A
0
Grobbelaar
FCS(SA)
Registrar
D A Hudson
FRCSEd
Consultant
The Hand Unit, University of Cape Town and Red Cross War Memorial Children's Hospital, Cape Town, South Africa
Key words: Primary repair; Flexor tendon
Tendon injuries to the thumb are uncommon in children. Nine children (mean age 6.1 years) with isolated complete injuries to the flexor pollicis longus (FPL) were treated with primary suture and controlled mobilisation at a major referral centre between 1985 and 1992. Five injuries occurred in zone I, two in zone m and two in zone V. One child developed sepsis and there were no cases of tendon rupture. Good or excellent results (Buck-Gramcko criteria) were achieved in seven of the nine children. Pinch grip after repair was similar to the non-injured hand. Primary repair and early controlled mobilisation of FPL leads to satisfactory results in children.
The outcome after repair of the flexor pollicis longus tendon (FPL) differs from the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) because it is thought to be anatomically less complex (1,2). Also, the functional characteristics of FPL are different to FDS and FDP (1). The usual methods used to assess FDS and FDP are inadequate when evaluating FPL tendon repair. In addition to range of motion, pinch grip and overall function of the thumb require assessment (1). FPL injuries are uncommon in children and there are few studies detailing outcome after early controlled mobilisation. This study reports on the outcome of flexor pollicis longus repair in nine children between 1985 and 1992 at a major referral centre.
Material and methods A retrospective analysis of isolated flexor pollicis longus injuries treated at the Red Cross War Memorial
Correspondence to: D A Hudson, Ward F16, Groote Schuur Hospital, Observatory 7925, Cape Town, South Africa
Children's Hospital between 1985 and 1992 was performed. This hospital only treats children up to the age of 13 years. Clinical data included age at presentation, nature of injury, associated injuries, treatment and outcome. Partial injuries were excluded. The results of
flexor pollicis longus excursion were graded using the criteria of Buck-Gramkco et al. (3). Pinch strength measurements were performed with a pinch meter (mmHg) and compared with that of the uninjured side. All flexor pollicis longus tendons are repaired primarily using a modified Kessler-Mason-Allen suture to approximate the tendon ends. The repair is then completed by a running 6/0 nylon suture placed around the margins of the tendon. The flexor sheath is approximated where possible. The hand is immobilised with a dorsal plaster slab for 4 weeks with the wrist in 300 flexion, the th~umb in a neutral position and the web space held wide open. An elastic band (4,5) was used in six cases where the child was old enough to co-operate with this type of rehabilitation. It was not used in three cases with ages ranging from 7 months to 3 years. Mobilisation begins the day after injury with passive extension of the digit. The elastic band was removed 4 weeks later and the child was encouraged to actively mobilise.
Results Nine children with FPL lacerations were seen during this period. There were eight males and one female. Age ranged from 7 months to 11 years (mean 6.1 years). All the tendons were repaired within 24 h of injury. The children were followed up for a period from 5 to 36 months (mean 13.8 months). The dominant hand was involved in four patients and the non-dominant hand in four patients. One patient was too young to judge his dominance. Six injuries were caused by glass, two by a knife and the other one by a sewing machine edge. Associated injuries are recorded in
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A 0 Grobbelaar and D A Hudson
Table I. Associated injuries 1 2 2
Digital nerve: single Digital nerve: both Digital artery
Table II. Results according to zone of injury, and outcome Results Excellent Good Fair Poor
Zone II
Zone III
Zone V
1 3
1
2
1
1
1
Table III. Overall results Results
Excellent Good Fair Poor
Number
Percentage
4 3 1 1
44.4 33.3 11.1 11.1
Table I. The zone of injury is recorded in Table II. Five tendon injuries occurred in zone II, two in zone III and two in zone V. The overall results are recorded in Table III and the results according to the zone of injury in Table II. Key pinch was measured by a pinch meter (mmHg). The result was tabulated as a percentage of the calculated strength, and in six of the nine patients the mean value was 93% (range 88-96%) compared with the uninjured thumb. Three patients, aged 7 months, 3 years and 1.5 years, respectively, were too young to give a reliable reading. Two of these children were responsible for the 'Poor' and 'Fair' readings. All children were reported by their parents to be functioning normally within their environment. No child endeavoured to change dominance of their hand because of the injury. Complications were uncommon. One child developed sepsis that required incision and drainage and achieved a 'poor' result. No tendon ruptures occurred and no patient required tenolysis.
Discussion There are few recent studies focusing on FPL repairs in children. There are two reasons for this: first, most studies have concentrated on injuries of FDS and FDP (4,5) and second, injuries to FPL are uncommon in children. In a series of 84 flexor tendon injuries treated variously in children, only 10 involved the thumb (6). Similarly, less than 10 children were reported in another series of 38 patients with FPL injuries (2). Most injuries in children occur from falling on a piece of glass and the other flexor tendons of the hand, usually of the little finger, are more commonly injured (7). Our study confirms that in children primary FPL repair
with early controlled mobilisation leads to satisfactory results, with 78% of the children achieving good or excellent results. This is especially noteworthy as five of the injuries occurred in zone II and all the repairs were performed by registrars in training, on indigent patients who attend follow-up irregularly. These results are better than those reported for a group of adults (2,9). The only poor result occurred in a child of poor social circumstances who developed an abscess that required incision and drainage. The reason for these satisfactory results is twofold. First, primary flexor tendon repair yields the best result (4,5). Second, healing in children is more rapid than in adults (10) owing to a better blood supply to the flexor tendons (11). Also, adhesions are more pliable in children (12) and no child has required tenolysis. There were no cases of tendon rupture whether an elastic band was applied or whether active mobilisation was started by the young child. However, the series is too small to draw any definite conclusions regarding active mobilisation. The usual methods of assessment applied to flexor tendon repair are insufficient to assess the results of FPL repair. Urbaniak and Goldner (1) claimed that the best indicator of thumb function is punch grip and the ability to perform the activities of daily living. In our series where pinch grip could be measured, an average pinch power of 93% was achieved compared with the normal side. Pinch was measured with the interphalangeal joint in flexion in an endeavour to concentrate on tip-to-tip pinch, and to diminish the role of adductor pollicis as the primary source of power. Considering the variables in measuring pinch (13), we feel that this translates to a completely functional hand. Primary FPL repair with early mobilisation is the treatment of choice for FPL injuries in children. Satisfactory results can be achieved irrespective of the zone of injury. An adequate tip-to-tip pinch grip and a fully functional hand can be expected.
References 1 Urbaniak JR, Goldner JL. Laceration of the flexor pollicis longus tendon; delayed repair by advancement, free graft or direct suture: a clinical and experimental study. J Bone Joint Surg 1973; 55A: 1123-47. 2 Nunley JA, Lewin LS, Devito D et al. Direct end-to-end repair of flexor pollicis longus tendon lacerations. J Hand Surg 1992; 17A: 118-21. 3 Buck-Gramcko D, Dietrich FE, Gogge S. Bewertungskriterien bei Nachuntersuchungen von Beugesehnenweiderherstellungen. Handchir 1976; 8: 65-9. 4 Kleinert HE, Kutz JE, Atasoy E et al. Primary repair of flexor tendons. Orthop Glin North Am 1973; 4: 865-76. S Lister GD, Kleinert HE, Kutz JE et al. Primary flexor tendon repair followed by immediate controlled mobilization. Jf Hand Surg 1977; 2: 441-51. 6 Vahvanen V, Gripenberg L, Nuutinen P. Flexor tendon injury of the hand in children. ScandJ3 Plast Surg 1981; 15:
43-8.
Flexor pollicis longus tendon injuries in children 7 Wakefield AR. Hand injuries in children. J Bone joint Surg 1964; 46A: 1226-34. 8 Early MJ, Milward TM. The primary repair of digital flexor tendons. Br J Plast Surg 1982; 35: 133-9. 9 Gault DT. A review of repaired flexor tendons. J Hand Surg 1987; 12B: 321-5. 10 Hemdon JH. Treatment of tendon injuries in children. Orthop Clin North Am 1976; 7: 717-31. 11 Verdan CE. Half a century of flexor tendon surgery. J Bone joint Surg 1972; 54A: 472-91.
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12 Arons MS. Purposeful delay of the primary repair of cut flexor tendons in 'some-man's-land' in children. Plast Reconstr Surg 1974; 53: 638-42. 13 Thomgren KG, Werner COP. Normal grip strength. Acta Orthop Scand 1979; 50: 225-9.
Received 24 August 1994
