Orthopedics

SPONTANEOUS RUPTURE OF DIGITAL FLEXOR TENDONS

Robert F McLain, MD; Curtis Steyers, MD; William Blair, MD

Abstract

Flexor tendon ruptures are fairly common in patients with rheumatoid arthritis; the flexor pollicis longus (FPL) or flexor digitorum profiindus (FDP) tendon to the index finger, weakened by tenosynovitis, rupture as they contact the scaphoid tubercle. Flexor tendon rupture in otherwise healthy individuals is usually associated with a bony abnormality such as scaphoid nonunion,1 Kienbock's disease,2*3 fractured hook of the hamate,4-6 or displaced distal radius fractures.7·9 Displaced bony fragments may erode through the volar wrist capsule and abrade the adjacent flexor tendon, producing a gradual, attritional rupture.10

Truly spontaneous flexor tendon ruptures are rare. The authors describe the presentation and treatment of three patients with spontaneous flexor tendon ruptures.

CASE REPORTS

Three patients with spontaneous rupture of a flexor tendon of the hand were treated between 1982 and 1987. Their charts, laboratory studies, and original radiographs were reviewed, and all patients returned for follow-up examination and interview. Mean interval between injury and surgical repair was 8.3 weeks (range: 3 to 16), and mean follow up was 2.7 years (range: 1 to 6). Range of motion (ROM), pinch strength, and power grip strength for both the involved hand and the uninvolved hand were measured at final follow up. Grip strength was measured using the Jamar dynamometer (Asimow Engineering, Los Angeles, Calif). Strength was recorded as the percentage of the uninvolved hand.

Case L A 65-year-old, right-handed man presented with sudden loss of right thumb flexion while shoveling dirt. Although passive ROM was normal and radiographs were unremarkable, the patient was unable to actively flex the interphalangeal joint of his right thumb. With attempts to flex the thumb he experienced burning pain at the volar, radial aspect of his wrist. A diagnosis of spontaneous rupture of the FPL tendon was made. Radiographic studies, including a carpal tunnel view, were all normal.

At surgery 6 weeks after injury, a rupture of the FPL tendon was identified; the proximal and distal tendon stumps were frayed and adherent to the surrounding tissues and the pulley system. There was no bony impingement, and there was no evidence of tenosynovitis along the path of the FPL. An intercalated palmaris longus tendon graft was used to repair the FPL tendon. Physical therapy was begun immediately, utilizing a dynamic flexion splint and active extension exercises.

The patient returned to work 6 weeks postoperatively and, at 1-year follow up, had returned to his previous job as a cafeteria worker without limitations. Grip and pinch strength were equal to the uninvolved side (Table 1), but IP joint motion was limited (Table 2).

Table

The patient had full passive ROM of the small finger, but had no active DIP or PIP flexion. Radiographs were normal. Although an immediate tendon repair was recommended, the patient refused.

Four months after his injury the patient underwent surgical exploration, revealing a mid-palmar rupture of both the FDP and FDS tendons to the small finger. There was no bony abnormality, no tenosynovitis, and no impingement within the tendon sheath. A transfer of the small FDP tendon to the ring FDP was performed, and the patient began dynamic flexion and active extension exercises postoperatively.

At 7 weeks the patient was able to actively flex and extend the small finger, but returned 1 week later with a recurrent rupture of the small finger FDP tendon. A re-repair was performed, and physical therapy was advanced under careful supervision. The patient was released to unrestricted activities 5 months after his second repair.

At 6-year follow up the patient had a 40° flexion contracture of the small finger (Table 2), but had a strong grip (Table 1 ) and excellent use of…

Flexor tendon ruptures are fairly common in patients with rheumatoid arthritis; the flexor pollicis longus (FPL) or flexor digitorum profiindus (FDP) tendon to the index finger, weakened by tenosynovitis, rupture as they contact the scaphoid tubercle. Flexor tendon rupture in otherwise healthy individuals is usually associated with a bony abnormality such as scaphoid nonunion,1 Kienbock's disease,2*3 fractured hook of the hamate,4-6 or displaced distal radius fractures.7·9 Displaced bony fragments may erode through the volar wrist capsule and abrade the adjacent flexor tendon, producing a gradual, attritional rupture.10

Truly spontaneous flexor tendon ruptures are rare. The authors describe the presentation and treatment of three patients with spontaneous flexor tendon ruptures.

CASE REPORTS

Three patients with spontaneous rupture of a flexor tendon of the hand were treated between 1982 and 1987. Their charts, laboratory studies, and original radiographs were reviewed, and all patients returned for follow-up examination and interview. Mean interval between injury and surgical repair was 8.3 weeks (range: 3 to 16), and mean follow up was 2.7 years (range: 1 to 6). Range of motion (ROM), pinch strength, and power grip strength for both the involved hand and the uninvolved hand were measured at final follow up. Grip strength was measured using the Jamar dynamometer (Asimow Engineering, Los Angeles, Calif). Strength was recorded as the percentage of the uninvolved hand.

Case L A 65-year-old, right-handed man presented with sudden loss of right thumb flexion while shoveling dirt. Although passive ROM was normal and radiographs were unremarkable, the patient was unable to actively flex the interphalangeal joint of his right thumb. With attempts to flex the thumb he experienced burning pain at the volar, radial aspect of his wrist. A diagnosis of spontaneous rupture of the FPL tendon was made. Radiographic studies, including a carpal tunnel view, were all normal.

At surgery 6 weeks after injury, a rupture of the FPL tendon was identified; the proximal and distal tendon stumps were frayed and adherent to the surrounding tissues and the pulley system. There was no bony impingement, and there was no evidence of tenosynovitis along the path of the FPL. An intercalated palmaris longus tendon graft was used to repair the FPL tendon. Physical therapy was begun immediately, utilizing a dynamic flexion splint and active extension exercises.

The patient returned to work 6 weeks postoperatively and, at 1-year follow up, had returned to his previous job as a cafeteria worker without limitations. Grip and pinch strength were equal to the uninvolved side (Table 1), but IP joint motion was limited (Table 2).

Table

Table 1GRIP STRENGTH AT FINAL FOLLOW UP

Table 1

GRIP STRENGTH AT FINAL FOLLOW UP

Table

Table 2ACTIVE RANGE OF MOTION AT FINAL FOLLOW UP

Table 2

ACTIVE RANGE OF MOTION AT FINAL FOLLOW UP

Case 2. A 78-year-old, right-handed man presented 3 weeks after developing a "cramp" in his right hand while climbing down a ladder, after which he could not flex his small finger. He had no other joint disease and denied any previous injury to the hand or arm.

On examination, active flexion of the small MCP joint was limited to 40°, with no active flexion of the PIP or DIP joints. There was mild tenderness to palpation in the mid-palmar region, but minimal swelling. Radiographs of the wrist, including a carpal tunnel view, were normal.

At surgery, the FDS and FDP tendons to the small fìnger were found to be ruptured in zone III. The tendon ends were frayed, but no tenosynovitis or bony abnormalities could be seen. Direct repair was not feasible, and an end-to-side transfer of the small FDP tendon to ring finger FDP tendon was performed.

At 1-year follow up the patient had good, painless function of the hand, with symmetrical grip strength (Table 1) and increased pinch strength of the ring and small fingers of the involved hand. There was a 45° fixed flexion contracture of the PIP joints of both ring and small fingers, which did not limit his activities in any way (Table 2).

Case 3. A 50-year-old, right-handed man presented 3 weeks after hyperextending his right fourth and fifth fingers, producing pain in the fifth MCP joint and in the palm of his hand, and inability to flex his small finger.

Table

Table 3LOCATION, PRESENTATION, AND DEMOGRAPHICS OF PATIENTS WITH SPONTANEOUS FLEXOR TENDON RUPTURES

Table 3

LOCATION, PRESENTATION, AND DEMOGRAPHICS OF PATIENTS WITH SPONTANEOUS FLEXOR TENDON RUPTURES

The patient had full passive ROM of the small finger, but had no active DIP or PIP flexion. Radiographs were normal. Although an immediate tendon repair was recommended, the patient refused.

Four months after his injury the patient underwent surgical exploration, revealing a mid-palmar rupture of both the FDP and FDS tendons to the small finger. There was no bony abnormality, no tenosynovitis, and no impingement within the tendon sheath. A transfer of the small FDP tendon to the ring FDP was performed, and the patient began dynamic flexion and active extension exercises postoperatively.

At 7 weeks the patient was able to actively flex and extend the small finger, but returned 1 week later with a recurrent rupture of the small finger FDP tendon. A re-repair was performed, and physical therapy was advanced under careful supervision. The patient was released to unrestricted activities 5 months after his second repair.

At 6-year follow up the patient had a 40° flexion contracture of the small finger (Table 2), but had a strong grip (Table 1 ) and excellent use of the hand. He had returned to his previous job without restrictions, and had no complaints relative to his hand.

DISCUSSION

Ruptures of flexor tendons in the hand are most common among patients with rheumatoid arthritis. Ruptures of the FPL are most common, as the tendon passes over the scaphoid and trapezium at the "critical corner" and impinges on bony prominences eroding through the volar capsule.11 Ruptures in non-rheumatoid patients are also attritional in nature, and have been reported in association with scaphoid nonunions,7 hook of the hamate fractures,4-6,12 Kienbock's disease,2'3-13 displaced distal radius fractures, and carpal dislocations.7-9,14

Spontaneous flexor tendon ruptures - those without associated intrinsic or extrinsic pathology - are very rare.15 Boyes et al16 reported three cases of spontaneous rupture in his series of 80 flexor tendon ruptures (Table 3). Folmar et al13 reported 10 cases of spontaneous rupture in a variety of tendons and at different levels. Of these 10 patients, only two were demonstrated to have intratendinous ruptures in the absence of intrinsic disease or bony abnormality. Imbriglia and Goldstein17 reported 10 cases of spontaneous rupture of the FDP to the small finger, but found no instance in which there was an associated rupture of the FDS tendon. Though they could not identify the actual cause of rupture, they proposed that the small finger FDP tendon was particularly susceptible to rupture because of the disproportionately smaller contribution of the small FSD to grip strength.

Ruptures rarely occur in the intratendinous portion of the tendon. McMaster18 has demonstrated that the weakest portions of the musculotendinous unit are the insertion and the musculotendinous junction, and that disruption of the intratendinous portion occurs only after 50% or more of the tendon substance has been divided. A segmental loss of blood supply to the flexor tendon was also shown to sufficiently alter tendon strength to predispose to intratendinous rupture.

None of our patients had any underlying bony abnormality that might have contributed to their rupture, and none had any evidence of tenosynovitis or rheumatoid disease. They were active, healthy individuals injured during moderate physical activities. Screening blood tests served to rule out rheumatoid arthritis, gout, or systemic illness as an underlying cause of rupture. All three had appropriate radiographs as well as direct inspection of the site of rupture, and no area of bony impingement or disruption of the volar capsule could be found. It seems likely that the tendon ruptures in these cases must have come as a result of an unusual peak strain superimposed on a tendon already weakened by repeated microtrauma or vascular compromise.

The dominant, right hand was involved in all three cases. Two of our patients suffered rupture of both flexors to the small finger, and the third suffered a spontaneous FPL rupture. Each of these patients presented with acute loss of function and mild pain at the site of rupture, and none had any prodromal symptoms of pain or weakness prior to rupture. None of these patients could recall feeling a "pop" at the time of injury.

The level of rupture was just distal to the carpal tunnel in each case. Tendon ends were frayed, but there was no invasive tenosynovitis. The two patients with FDP and FDS ruptures of the small finger underwent small FDP tendon-toring FDP tendon transfers. One of these patients required a second procedure when the anastomosis ruptured during physical therapy. The third patient received an intercalated palmaris longus graft to repair his FPL injury. No evidence of tenosynovitis, chronic inflammation, or bony impingement was found in any case.

Grip strength, as measured by the Jamar dynamometer, returned to near normal levels early, while pinch strength was less consistent. Mean grip strength measured 106%, 107%, and 110%, respectively, of the uninvolved hand. Pinch strength was less consistent. Patient 1, with an FPL rupture, developed 94% key and chuck pinch strength compared to his uninvolved hand; patient 2 had thumb to small finger pinch equal to 111% of the opposite hand. Patient 3 had thumb to small pinch of only 23% relative to the opposite hand; poor ROM hampered his ability to oppose thumb and small fìnger, resulting in a poor pinch despite good digital strength.

Flexion contractures were the most significant problem for these patients, with patients 2 and 3 complaining of occasional difficulty using gloves due to contractures (Table 2). Patient 1 had no complaints relative to his stiffness, but was aware of the decreased ROM. All three patients had complied with their postoperative therapy programs, but did not regain full ROM.

Within 6 months of surgical repair all three patients had returned to the same jobs and activities that they had prior to rupture. All were very satisfied with their function, and wanted no further treatment.

Functional outcome in non-rheumatoid patients with flexor tendon ruptures has generally been good, but many authors have reported a significant loss of motion in the affected digit, particularly in PIP and DIP joint motion.14'19"21 Imbriglia and Goldstein17 emphasized the advantages of early repairs in rupture of the small finger FDP, and reported total active motion of greater than 125° in six of seven patients. The only patient with significant loss of motion was treated 2.5 years after his initial injury. PIP motion of 50° to 75° was obtained in the three patients treated nonoperatively. Most important, nine of 10 patients returned to work at their preinjury level of function.

These attritional ruptures are not amenable to primary tendon repairs and require transfers or tendon graft repairs. Loss of motion occurred in our patients despite carefully monitored therapy and good patient motivation. None of our patients had surgery sooner than 4 weeks following their injury, and we suggest that earlier treatment would result in better motion postoperatively. Although each was aware of the loss of motion in the affected digits, these patients were well satisfied with the results of their treatment and had returned to their previous level of function within 1 year of surgery.

REFERENCES

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2. Hallett JP, Motta GR. Tendon ruptures of the hand with particular reference to attrition ruptures in the carpal tunnel. Hand. 1982; 14:283-290.

3. Masada K, Kawabata H, Ono K. Pathologic rupture of flexor tendons due to longstanding Kienbock's disease. J Hand Surg. 1987; 12:22-25.

4. Minami A, Ogino T, Usui M, Ishìi S. Finger tendon rupture secondary to fracture of the hamate: a case report. Acta Orthop Scand. 1985; 56:96-97.

5. Okuhara T, Matsui T, Sugimoto Y. Spontaneous rupture of the flexor tendons of the little finger due to projection of the hook of the hamate. Hand. 1982; 14:71-74.

6. Takami H, Takahashi S, Ando M. Rupture of flexor tendon associated with previous fracture of the hook of the hamate. Hand. 1983; 15:73-76.

7. Rymaszewski LA, Walker AP. Rupture of the flexor digitorum profundus to the index finger after a distal radius fracture. J Hand Surg. 1987; 128:115-116.

8. Wong FY, Pho RW. Median nerve compression, with tendon ruptures, after Colles' fracture. J Hand Surg. 1984; 9:139-141.

9. Younger CP, DeFiore JC. Rupture of flexor tendons of the fingers after a Colles fracture: a case report. J Bone Joint Surg. 1977; 59A:828-829.

10. McLain RF, Steyer C. Tendon ruptures with scaphoid nonunion. Clin Orthop. 1990; 225:117-120.

1 1 . Mannerfelt F, Norman O. Attrition ruptures of flexor tendons in rheumatoid arthritis caused by bony spurs in the carpal tunnel. J Bone Joint Surg. 1969; 5 18:270-277.

12. Crosby EB, Linscheid RL. Rupture of the flexor profundus tendon of the ring finger secondary to ancient fracture of the hook of the hamate. J Bone Joint Surg. 1 974; 56A:1076-1078.

13. Folmar RC, Nelson CL, Phalen GS. Ruptures of the flexor tendons in hands of non-rheumatoid patients. J Bone Joint Surg. 1972; 54A:579-584.

14. Stem PJ. Multiple flexor tendon ruptures following old anterior dislocation of the lunate. J Bone Joint Surg. 1981;63A:489-490.

15. Matthews RN, Walton JN. Spontaneous rupture of both flexor tendons in a single digit. J Hand Surg. 1984; 9B: 134- 136.

16. Boyes JH, Wilson JN, Smith JW. Flexor tendon ruptures in the forearm and hand. / Bone Joint Surg. 1960; 42A:637-646.

17. Imbriglia JE, Goldstein SA. Intratendinous ruptures of the flexor digitorum profundas tendon of the small finger J Hand Surg. 1987; 12A:985-991.

18. McMaster PE. Tendon and muscle ruptures. Clinical and experimental studies on the causes and location of subcutaneous ruptures. J Bone Joint Surg. 1933; 15:705722.

19. Fambrough RA, Green DP. Tendon rupture as a complication of screw fixation in fractures in the hand. / Bone Joint Surg. 1979; 61A:781-782.

20. James JIP. A case of rupture of flexor tendons secondary to Kienbock's disease. J Bone Joint Surg. 1949; 316:521-523.

21. Thomsen S, Falstie-Jensen S. Rupture of the flexor pollicis longus tendon associated with an ununited fracture of the scaphoid. J Hand Surg. 1988; 13A:220-222.

Table 1

GRIP STRENGTH AT FINAL FOLLOW UP

Table 2

ACTIVE RANGE OF MOTION AT FINAL FOLLOW UP

Table 3

LOCATION, PRESENTATION, AND DEMOGRAPHICS OF PATIENTS WITH SPONTANEOUS FLEXOR TENDON RUPTURES

10.3928/0147-7447-19940301-11

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