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Biomechanical analysis of a step-cut technique for flexor tendon repair
BIOMECHANICAL ANALYSIS OF A STEP-CUT FOR FLEXOR TENDON REPAIR L. GORDON, J. L. GARRISON,
J. C. CHENG,
Y. K. LIU, R. P. NATHAN
TECHNIQUE
and D. G. LEVINSOHN
From the Department of Orthopaedic Surgery, Hand and Microsurgery Service, UCSF School of Medicine, San Francisco, U.S.A.
We compared the strength of a new step-cut technique for flexor tendon repair with that of the widely used Kessler-Tajima technique, giving special attention to the relative contributions of the core and epitendinous sutures. 36 flexor digitorum profundus tendons from human cadavers were used. Corresponding digits from the same donor were paired, and the two tendons of each pair were placed in the Kessler-Tajima and step-cut groups, respectively. Each group had three subcategories of repair: (1) core repair alone; (2) epitendinous repair alone; and (3) full repair. In the KesslerTajima repair, the core stitch contributed more to ultimate tensile strength, while the epitendinous stitch contributed more to gap formation resistance. In the step-cut repair, however, the epitendinous stitch contributed more to both measures of strength. The full step-cut repair was 65% stronger in resisting gap formation and had 84% more ultimate tensile strength than the full Kessler-Tajima repair. We attribute the greater strength of the step-cut repair to the additional number of epitendinous loops, which lie perpendicular to the long axis of the tendon. Journal of Hand Surgery (British Volume, 1992) 17B: 282-285 of repair and compares it with that of the Kessler-Tajima repair. As part of this investigation, the relative contributions of the core and epitendinous stitches to the overall strength of both types of repair were also evaluated.
Following the repair of zone 2 flexor tendon lacerations, controlled passive mobilization, i.e., active extension and passive flexion, has been shown to be superior to immobilization (Strickland and Glogovac, 1980; Citron and Forster, 1987). Experimental studies have demonstrated that early mobilization not only decreases adhesion formation (Gelberman et al., 1983; Hitchcock et al., 1987) but also enhances the strength of the repair (Hitchcock et al., 1987; Feehan and Beauchene, 1990), and the clinical results obtained so far with early active mobilization have been promising (Small et al., 1989). Despite the evidence favouring its use, there is a reluctance to adopt early active mobilization in case the load it places on the tendon exceeds the strength of the repair (Lister et al., 1990). Urbaniak et al. (1975) found that intact human tendons experience 250 g. of load in passive flexion, 1.5 kg. in moderate active flexion, and 5 kg. in strong flexion. Although the widely used KesslerTajima tendon repair (Tajima, 1984) has been shown to withstand between 2 and 3 kg. of loading in vitro (Urbaniak et al., 1975; Wade et al., 1986; Pruitt et al., 1989), the strength of the repair diminishes substantially within the first week because of tendon softening (Mason and Allen, 1941; Urbaniak et al., 1975). Stronger tendon repairs have been developed in the hope that they could better withstand early active mobilization (Becker, 1978; Savage, 1985). The clinical results of these methods have been encouraging (Becker et al., 1979; Savage and Risitano, 1989), but their complexity limits their usefulness. In response to the continued need for a stronger and more practical tendon repair, we developed a technique that is simple and provides greater strength through an epitendinous stitch that has a number of loops placed perpendicular to the long axis of the tendon. Recently, the epitendinous stitch has been shown to play an important role in strength of repair (Wade et al., 1986; Pruitt et al., 1989). This study measures the strength of the new technique
Materials and methods 36 flexor digitorum profundus tendons from human cadavers were studied. The donor limbs, which had been frozen shortly after death, were thawed at room temperature before use. Corresponding digits from the same donor were paired, and the two tendons of each pair were placed in the Kessler-Tajima and step-cut repair groups, respectively. Each group had three subcategories of repair: (1) core repair alone; (2) epitendinous repair alone; and (3) full repair, i.e. both the core and epitendinous repair. The tendons were exposed in zone 2. Those to be repaired by the Kessler-Tajima technique were divided transversely with a scalpel, and in those to be repaired by the step-cut technique, sharp scissors were used to make a step, which involved 0.5 cm. of shortening (Fig. 1). The core stitch was essentially the same in both techniques, using a 4/O monofilament nylon suture. In both groups the epitendinous repair was done with a simple running stitch using a 6/O monofilament polypropylene suture that followed the line of the tendon laceration (Fig. 2). In the Kessler-Tajima technique, an average of 18 longitudinally oriented epitendinous loops were placed approximately 1 mm. apart. The longitudinal incision created by the step-cut allowed an additional 12 transversely oriented epitendinous loops to be placed. Following repair, the tendons were excised at their musculotendinous junctions, and the digits were disarticulated at the level of the distal interphalangeal joint. The tendons were immediately placed in normal saline 282
STEP-CUT
TECHNIQUE
FOR
FLEXOR
TENDON
REPAIR
_-___
0.5cm
1
I , I I I I
0.5cm
Fig. 1
The step-cut
involves 0.5 cm. of shortening.
283
and taken to an adjacent room for biomechanical testing on a computer-controlled servohydraulic mechanical testing machine (M.M.E.D. ; Matco, La Canada, CA). Custom-designed clamps were used to mount the tendons on the machine. The repaired tendons were fixed to the upper clamp by threading the proximal free end of the tendon through a slot at the base of a cup-shaped holding fixture ; the distal phalanx rested on the solid part of the cup surrounding the slot. This configuration securely restrained the phalanx while allowing the tensile load to be entireky sustained by the tendon and its bony insertion. The proximal end of the tendon was set between the serrated jaws of a lower clamp to which antislip adhesive paper (No. 8562; 3M Company, St Paul, MN) had been applied. The jaws were then tightened to firmly grasp the tendon. The M.M.E.D. machine was programmed to pull tendons in uniaxial tension until failure at a crosshead speed of 0.2 mm./minute. Load characteristics were directly plotted on an X-Y chart recorder, and a loadversus-displacement graph was obtained. A ruler with millimetre markings was placed parallel to the tendon, and a high-powered video recorder was used to visualize the tendon as it was being pulled. The point at which a 2 mm. gap developed between the tendon ends was noted on the chart recording. The ultimate tensile strength was
b
Fig. 2
Full repair (core and epitendinous
stitches)
in (a) the Kessler-Tajima
technique
and (b) the step-cut
technique.
284
THE
JOURNAL
OF HAND
SURGERY
VOL.
17B No. 3 JUNE
1992
Core alone
4-H L 3
Epitendinous alone
?? Full
3 _ 0
Load between 2 mm gap & ultimate tensile strength
0 Fig. 3
Strength
T
Kessler-Tajima
of flexor tendon repair:
comparison
of the step-cut
Z-Plasty
and Kessler-Tajima
taken as the peak load value. Computer-generated raw data from the load and displacement cells were also obtained. Results from corresponding digits of the same donor were compared using the paired Student’s t-test. The remaining comparisons were made using the unpaired Student’s t-test. P values of 0.05 or less were regarded as significant.
techniques.
epitendinous stitch was more resistant to gap formation. In the step-cut repair, however, the epitendinous stitch contributed more to both measures to strength (Table 2). Discussion
The results are summarized in Figure 3. The core stitches of the Z-Plasty and Kessler-Tajima techniques were similar in their ability to resist gap formation and provide ultimate tensile strength. However, the epitendinous repair of the step-cut technique was significantly stronger than that of the Kessler-Tajima repair in both these measures of strength. Likewise, the full step-cut repair was significantly better able to resist gap formation and provide ultimate tensile strength compared with the full Kessler-Tajima repair (Table 1). In the full Kessler-Tajima repair, the core stitch contributed more to ultimate tensile strength, while the
We have shown that the step-cut technique provides a significantly stronger tendon repair than does the KesslerTajima technique. In both methods, the epitendinous stitch plays a greater part in resisting gap formation than the core stitch, a finding consistent with the previous work of Wade et al. (1986) and Pruitt et al. (1991). The epitendinous stitch of the step-cut repair also contributes relatively more to the ultimate tensile strength. We attribute the greater strength of the step-cut repair to the additional number of epitendinous loops, which are perpendicular to the long axis of the tendon. Having established the superior strength of this repair in vitro, the important questions remaining to be answered relate to clinical utility. What are the consequences of shortening the tendon by 0.5 cm., the effect of the longitudinal cut on healing, and the effect of the additional epitendinous loops on adhesion formation?
Table l-Strength of flexor tendon repair: comparison of the step-cut and Kessler-Tajima techniques
Table 2-Strength and core stitches
Results
S-C vs K-T Core stitch
S-C OSK-T Epitendinous stitch
S-C us K-T Full repair
Gap formation resistance*
32% (P> 0.4)
67% (PCO.002)
65% (PCO.02)
Ultimate tensile strength
-5% (P10.6)
121% (P
84% (P
*at2mm.
of flexor tendon repair: comparison of the epitendinous
Epi us core Kessler-Tajima
Epi us core step-cut
Gap Formation Resistance*
125% (P
259% (P<0.0001)
Ultimate Tensile Strength
-33% (P
57% (P
*at 2 mm.
STEP-CUT
TECHNIQUE
FOR
FLEXOR
TENDON
REPAIR
Available data suggest that these issues need not be of critical concern. A cadaver study by Malerich et al. (1987) determined that the profundus tendon could be shortened by up to 1 cm., while the bevel technique of Becker, which involves 0.75 cm. of shortening, has achieved good results (Becker, 1978). Although the stepcut might disrupt the blood supply more than a conventional technique would, tendon healing can occur even in the absence of an intact blood supply, the nutrition being provided by synovial fluid (Mass and Tuel, 1989). Acknowledgements The authors thank Judith Simon for preparing the manuscript, of Davis & Geck for supplying the suture material.
and Janet Portman
References BECKER, H. (1978). Primary repair of flexor tendons in the hand without immobilisation-preliminary report. The Hand, 10: 1: 3747. BECKER, H., ORAK, F. and DUPONSELLE, E. (1979). Early active motion following a beveled technique of flexor tendon repair: report on fifty cases. Journal of Hand Surgery, 4 : 5 : 454460. CITRON, N. D. and FORSTER, A. (1987). Dynamic splinting following flexor tendon repair. Journal of Hand Surgery, 12B: 1: 96100. CULLEN, K. W., TOLHURST, P., LANG, D. and PAGE, R. E. (1989). Flexor tendon repair in zone 2 followed by controlled active mobilisation. Journal of Hand Surgery, 14B: 4: 392-395. FARKAS, L. G., HERBERT, M. A. and JAMES, J. S. (1980A). Peritendinous healing after early movement of repaired flexor tendon: anatomical study. Annals of Plastic Surgery, 5: 4: 298-304. FARKAS, L. G., HERBERT, M. A. and JAMES, J. S. (1980B). Does early movement speed the recovery of function of repaired flexor tendon? Annals of Plastic Surgery, 5: 4: 305-308. FEEHAN, L. M. and BEAUCHENE, J. G. (1990). Early tensile properties of healing chicken flexor tendons: early controlled passive motion versus postoperative immobilization. Journal of Hand Surgery, 15A: 1: 63-68. GELBERMAN, R. H., VANDE BERG, J. S., LUNDBORG, G. N. and AKESON, W. H. (1983). Flexortendon healing and restorationofthe gliding surface. Journal of Bone and Joint Surgery, 65A: 1: 70-80. GELBERMAN, R. H., WOO, S. L.-Y., LOTHRINGER, K., AKESON, W. H. and AMIEL, D. (1982). Effects of early intermittent passive mobilization on healing canine flexor tendons. Journal of Hand Surgery, 7: 2: 17&175. HITCHCOCK, T. F., LIGHT, T. R., BUNCH, W. H., KNIGHT, G. W., SARTORI, M. J., PATWARDHAN, A. G. and HOLLYFIELD, R. L.
285 (1987). The effect of ilmmediate constrained digital motion on the strength of repairs in chickens. Journal of Hand Surgery, 12A : 4: 590-595. JABALEY, M. E., LISTER, G. D., MANSKE, P. R., SCHNEIDER, L. H. and STRICKLAND, J. W. (1990). Symposium: flexor tendon repair. Contemporary Orthopaedics, 20: 4: 421460. MacMILLAN, M., SHEPPARD, J. E. and DELL, P. C. (1987). Anexperimental flexor tendon repair in zone II that allows immediate postoperative mobilization. Journalof Hand Surgery, 12A: 4: 582-589. MALERICH, M. M., BAIRD, R. A., McMASTER, W. and ERICKSON, J. M. (1987). Permissible limits of flexor digitorum profundus tendon advancement-an anatomic study. Journal of Hand Surgery, 12A: 1: 3&33. MANSKE, P. R. and LESKER, P. (1982). Nutrient pathways of flexor tendons in primates. Journal of Hand Surgery, 7A: 5: 436488. MASON, M. L. and ALLEN, H. S. (1941). The rate of healing of tendons. An experimental study of tensile strength. Annals of Surgery, 113: 424459. MASS, D. P. and TUEL, R. (1989). Human flexor tendon oarticiuation in the in vitro repair process. Journal of HandSurgery, 14A: 1:64-71: PRIBAZ, J. J., MORRISON, W. A. and MACLEOD, A. M. (1989). Primary repair of flexor tendons in no-man’s land using the Becker repair. Journal of Hand Surgery, 14B: 4: 400-405. PRUITT, D. L., MANSKE, P. R. and FINK, B. (1991). Cyclic stress analysis of flexor tendon repair. Journal of Hand Surgery, 16A: 4: 701-707. SAVAGE, R. (1985). In vitro studies of a new method of gexor tendon repair. Journalof Hand Surgery, 10B: 2: 135-141. SAVAGE, R. and RISITANO, G. (1989). Flexor tendon repair using a “six strand” method of repair and early active mobilisation. Journal of Hand Surgery, 14B: 4: 396399. SMALL, J. O., BRENNEN, M. D. and COLVILLE, J. (1989). Early active mobilisation following flexor tendon repair in zone 2. Journal of Hand Surgery, 14B: 4: 383-391. STRICKLAND, J. W. and GLOGOVAC, S. V. (1980). Digital function following flexor tendon repair in zone II: a comparison of immobilization and controlled passive motion techniques. Journal of Hand Surgery, 5A: 6: 53743. TAJIMA, T. (1984). History, current status, and aspects of hand surgery in Japan. Clinical Orthopaedics and Related Research, 184: 4149. URBANIAK, J. R., CAHILL, J. D. and MORTENSON, R. A. Tendon suturing methods: analysisoftensile strengths. In: American Academyoforthopaedic Surgeons. Symposium on Tendon Surgery in the Hand. St. Louis, C.V. Mosby, 1975: 70-80. WADE, P. J. F., MUIR, I. F. K. and HUTCHEON, L. L. (1986). Primarytlexor tendon repair: the mechanical limitations of the modified Kessler technique. Journal of Hand Surgery, 11B: 1: 71-76.
flexortendon
Accepted: 23 May 1991 Leonard Gordon, M.D., U.C.S.F. CA94143,U.S.A. 0 1992 The British
School of Medicine,
Society for Surgery
of the Hand
400 Pamassus,
Suite 636, San Francisco,
J. C. CHENG,
Y. K. LIU, R. P. NATHAN
TECHNIQUE
and D. G. LEVINSOHN
From the Department of Orthopaedic Surgery, Hand and Microsurgery Service, UCSF School of Medicine, San Francisco, U.S.A.
We compared the strength of a new step-cut technique for flexor tendon repair with that of the widely used Kessler-Tajima technique, giving special attention to the relative contributions of the core and epitendinous sutures. 36 flexor digitorum profundus tendons from human cadavers were used. Corresponding digits from the same donor were paired, and the two tendons of each pair were placed in the Kessler-Tajima and step-cut groups, respectively. Each group had three subcategories of repair: (1) core repair alone; (2) epitendinous repair alone; and (3) full repair. In the KesslerTajima repair, the core stitch contributed more to ultimate tensile strength, while the epitendinous stitch contributed more to gap formation resistance. In the step-cut repair, however, the epitendinous stitch contributed more to both measures of strength. The full step-cut repair was 65% stronger in resisting gap formation and had 84% more ultimate tensile strength than the full Kessler-Tajima repair. We attribute the greater strength of the step-cut repair to the additional number of epitendinous loops, which lie perpendicular to the long axis of the tendon. Journal of Hand Surgery (British Volume, 1992) 17B: 282-285 of repair and compares it with that of the Kessler-Tajima repair. As part of this investigation, the relative contributions of the core and epitendinous stitches to the overall strength of both types of repair were also evaluated.
Following the repair of zone 2 flexor tendon lacerations, controlled passive mobilization, i.e., active extension and passive flexion, has been shown to be superior to immobilization (Strickland and Glogovac, 1980; Citron and Forster, 1987). Experimental studies have demonstrated that early mobilization not only decreases adhesion formation (Gelberman et al., 1983; Hitchcock et al., 1987) but also enhances the strength of the repair (Hitchcock et al., 1987; Feehan and Beauchene, 1990), and the clinical results obtained so far with early active mobilization have been promising (Small et al., 1989). Despite the evidence favouring its use, there is a reluctance to adopt early active mobilization in case the load it places on the tendon exceeds the strength of the repair (Lister et al., 1990). Urbaniak et al. (1975) found that intact human tendons experience 250 g. of load in passive flexion, 1.5 kg. in moderate active flexion, and 5 kg. in strong flexion. Although the widely used KesslerTajima tendon repair (Tajima, 1984) has been shown to withstand between 2 and 3 kg. of loading in vitro (Urbaniak et al., 1975; Wade et al., 1986; Pruitt et al., 1989), the strength of the repair diminishes substantially within the first week because of tendon softening (Mason and Allen, 1941; Urbaniak et al., 1975). Stronger tendon repairs have been developed in the hope that they could better withstand early active mobilization (Becker, 1978; Savage, 1985). The clinical results of these methods have been encouraging (Becker et al., 1979; Savage and Risitano, 1989), but their complexity limits their usefulness. In response to the continued need for a stronger and more practical tendon repair, we developed a technique that is simple and provides greater strength through an epitendinous stitch that has a number of loops placed perpendicular to the long axis of the tendon. Recently, the epitendinous stitch has been shown to play an important role in strength of repair (Wade et al., 1986; Pruitt et al., 1989). This study measures the strength of the new technique
Materials and methods 36 flexor digitorum profundus tendons from human cadavers were studied. The donor limbs, which had been frozen shortly after death, were thawed at room temperature before use. Corresponding digits from the same donor were paired, and the two tendons of each pair were placed in the Kessler-Tajima and step-cut repair groups, respectively. Each group had three subcategories of repair: (1) core repair alone; (2) epitendinous repair alone; and (3) full repair, i.e. both the core and epitendinous repair. The tendons were exposed in zone 2. Those to be repaired by the Kessler-Tajima technique were divided transversely with a scalpel, and in those to be repaired by the step-cut technique, sharp scissors were used to make a step, which involved 0.5 cm. of shortening (Fig. 1). The core stitch was essentially the same in both techniques, using a 4/O monofilament nylon suture. In both groups the epitendinous repair was done with a simple running stitch using a 6/O monofilament polypropylene suture that followed the line of the tendon laceration (Fig. 2). In the Kessler-Tajima technique, an average of 18 longitudinally oriented epitendinous loops were placed approximately 1 mm. apart. The longitudinal incision created by the step-cut allowed an additional 12 transversely oriented epitendinous loops to be placed. Following repair, the tendons were excised at their musculotendinous junctions, and the digits were disarticulated at the level of the distal interphalangeal joint. The tendons were immediately placed in normal saline 282
STEP-CUT
TECHNIQUE
FOR
FLEXOR
TENDON
REPAIR
_-___
0.5cm
1
I , I I I I
0.5cm
Fig. 1
The step-cut
involves 0.5 cm. of shortening.
283
and taken to an adjacent room for biomechanical testing on a computer-controlled servohydraulic mechanical testing machine (M.M.E.D. ; Matco, La Canada, CA). Custom-designed clamps were used to mount the tendons on the machine. The repaired tendons were fixed to the upper clamp by threading the proximal free end of the tendon through a slot at the base of a cup-shaped holding fixture ; the distal phalanx rested on the solid part of the cup surrounding the slot. This configuration securely restrained the phalanx while allowing the tensile load to be entireky sustained by the tendon and its bony insertion. The proximal end of the tendon was set between the serrated jaws of a lower clamp to which antislip adhesive paper (No. 8562; 3M Company, St Paul, MN) had been applied. The jaws were then tightened to firmly grasp the tendon. The M.M.E.D. machine was programmed to pull tendons in uniaxial tension until failure at a crosshead speed of 0.2 mm./minute. Load characteristics were directly plotted on an X-Y chart recorder, and a loadversus-displacement graph was obtained. A ruler with millimetre markings was placed parallel to the tendon, and a high-powered video recorder was used to visualize the tendon as it was being pulled. The point at which a 2 mm. gap developed between the tendon ends was noted on the chart recording. The ultimate tensile strength was
b
Fig. 2
Full repair (core and epitendinous
stitches)
in (a) the Kessler-Tajima
technique
and (b) the step-cut
technique.
284
THE
JOURNAL
OF HAND
SURGERY
VOL.
17B No. 3 JUNE
1992
Core alone
4-H L 3
Epitendinous alone
?? Full
3 _ 0
Load between 2 mm gap & ultimate tensile strength
0 Fig. 3
Strength
T
Kessler-Tajima
of flexor tendon repair:
comparison
of the step-cut
Z-Plasty
and Kessler-Tajima
taken as the peak load value. Computer-generated raw data from the load and displacement cells were also obtained. Results from corresponding digits of the same donor were compared using the paired Student’s t-test. The remaining comparisons were made using the unpaired Student’s t-test. P values of 0.05 or less were regarded as significant.
techniques.
epitendinous stitch was more resistant to gap formation. In the step-cut repair, however, the epitendinous stitch contributed more to both measures to strength (Table 2). Discussion
The results are summarized in Figure 3. The core stitches of the Z-Plasty and Kessler-Tajima techniques were similar in their ability to resist gap formation and provide ultimate tensile strength. However, the epitendinous repair of the step-cut technique was significantly stronger than that of the Kessler-Tajima repair in both these measures of strength. Likewise, the full step-cut repair was significantly better able to resist gap formation and provide ultimate tensile strength compared with the full Kessler-Tajima repair (Table 1). In the full Kessler-Tajima repair, the core stitch contributed more to ultimate tensile strength, while the
We have shown that the step-cut technique provides a significantly stronger tendon repair than does the KesslerTajima technique. In both methods, the epitendinous stitch plays a greater part in resisting gap formation than the core stitch, a finding consistent with the previous work of Wade et al. (1986) and Pruitt et al. (1991). The epitendinous stitch of the step-cut repair also contributes relatively more to the ultimate tensile strength. We attribute the greater strength of the step-cut repair to the additional number of epitendinous loops, which are perpendicular to the long axis of the tendon. Having established the superior strength of this repair in vitro, the important questions remaining to be answered relate to clinical utility. What are the consequences of shortening the tendon by 0.5 cm., the effect of the longitudinal cut on healing, and the effect of the additional epitendinous loops on adhesion formation?
Table l-Strength of flexor tendon repair: comparison of the step-cut and Kessler-Tajima techniques
Table 2-Strength and core stitches
Results
S-C vs K-T Core stitch
S-C OSK-T Epitendinous stitch
S-C us K-T Full repair
Gap formation resistance*
32% (P> 0.4)
67% (PCO.002)
65% (PCO.02)
Ultimate tensile strength
-5% (P10.6)
121% (P
84% (P
*at2mm.
of flexor tendon repair: comparison of the epitendinous
Epi us core Kessler-Tajima
Epi us core step-cut
Gap Formation Resistance*
125% (P
259% (P<0.0001)
Ultimate Tensile Strength
-33% (P
57% (P
*at 2 mm.
STEP-CUT
TECHNIQUE
FOR
FLEXOR
TENDON
REPAIR
Available data suggest that these issues need not be of critical concern. A cadaver study by Malerich et al. (1987) determined that the profundus tendon could be shortened by up to 1 cm., while the bevel technique of Becker, which involves 0.75 cm. of shortening, has achieved good results (Becker, 1978). Although the stepcut might disrupt the blood supply more than a conventional technique would, tendon healing can occur even in the absence of an intact blood supply, the nutrition being provided by synovial fluid (Mass and Tuel, 1989). Acknowledgements The authors thank Judith Simon for preparing the manuscript, of Davis & Geck for supplying the suture material.
and Janet Portman
References BECKER, H. (1978). Primary repair of flexor tendons in the hand without immobilisation-preliminary report. The Hand, 10: 1: 3747. BECKER, H., ORAK, F. and DUPONSELLE, E. (1979). Early active motion following a beveled technique of flexor tendon repair: report on fifty cases. Journal of Hand Surgery, 4 : 5 : 454460. CITRON, N. D. and FORSTER, A. (1987). Dynamic splinting following flexor tendon repair. Journal of Hand Surgery, 12B: 1: 96100. CULLEN, K. W., TOLHURST, P., LANG, D. and PAGE, R. E. (1989). Flexor tendon repair in zone 2 followed by controlled active mobilisation. Journal of Hand Surgery, 14B: 4: 392-395. FARKAS, L. G., HERBERT, M. A. and JAMES, J. S. (1980A). Peritendinous healing after early movement of repaired flexor tendon: anatomical study. Annals of Plastic Surgery, 5: 4: 298-304. FARKAS, L. G., HERBERT, M. A. and JAMES, J. S. (1980B). Does early movement speed the recovery of function of repaired flexor tendon? Annals of Plastic Surgery, 5: 4: 305-308. FEEHAN, L. M. and BEAUCHENE, J. G. (1990). Early tensile properties of healing chicken flexor tendons: early controlled passive motion versus postoperative immobilization. Journal of Hand Surgery, 15A: 1: 63-68. GELBERMAN, R. H., VANDE BERG, J. S., LUNDBORG, G. N. and AKESON, W. H. (1983). Flexortendon healing and restorationofthe gliding surface. Journal of Bone and Joint Surgery, 65A: 1: 70-80. GELBERMAN, R. H., WOO, S. L.-Y., LOTHRINGER, K., AKESON, W. H. and AMIEL, D. (1982). Effects of early intermittent passive mobilization on healing canine flexor tendons. Journal of Hand Surgery, 7: 2: 17&175. HITCHCOCK, T. F., LIGHT, T. R., BUNCH, W. H., KNIGHT, G. W., SARTORI, M. J., PATWARDHAN, A. G. and HOLLYFIELD, R. L.
285 (1987). The effect of ilmmediate constrained digital motion on the strength of repairs in chickens. Journal of Hand Surgery, 12A : 4: 590-595. JABALEY, M. E., LISTER, G. D., MANSKE, P. R., SCHNEIDER, L. H. and STRICKLAND, J. W. (1990). Symposium: flexor tendon repair. Contemporary Orthopaedics, 20: 4: 421460. MacMILLAN, M., SHEPPARD, J. E. and DELL, P. C. (1987). Anexperimental flexor tendon repair in zone II that allows immediate postoperative mobilization. Journalof Hand Surgery, 12A: 4: 582-589. MALERICH, M. M., BAIRD, R. A., McMASTER, W. and ERICKSON, J. M. (1987). Permissible limits of flexor digitorum profundus tendon advancement-an anatomic study. Journal of Hand Surgery, 12A: 1: 3&33. MANSKE, P. R. and LESKER, P. (1982). Nutrient pathways of flexor tendons in primates. Journal of Hand Surgery, 7A: 5: 436488. MASON, M. L. and ALLEN, H. S. (1941). The rate of healing of tendons. An experimental study of tensile strength. Annals of Surgery, 113: 424459. MASS, D. P. and TUEL, R. (1989). Human flexor tendon oarticiuation in the in vitro repair process. Journal of HandSurgery, 14A: 1:64-71: PRIBAZ, J. J., MORRISON, W. A. and MACLEOD, A. M. (1989). Primary repair of flexor tendons in no-man’s land using the Becker repair. Journal of Hand Surgery, 14B: 4: 400-405. PRUITT, D. L., MANSKE, P. R. and FINK, B. (1991). Cyclic stress analysis of flexor tendon repair. Journal of Hand Surgery, 16A: 4: 701-707. SAVAGE, R. (1985). In vitro studies of a new method of gexor tendon repair. Journalof Hand Surgery, 10B: 2: 135-141. SAVAGE, R. and RISITANO, G. (1989). Flexor tendon repair using a “six strand” method of repair and early active mobilisation. Journal of Hand Surgery, 14B: 4: 396399. SMALL, J. O., BRENNEN, M. D. and COLVILLE, J. (1989). Early active mobilisation following flexor tendon repair in zone 2. Journal of Hand Surgery, 14B: 4: 383-391. STRICKLAND, J. W. and GLOGOVAC, S. V. (1980). Digital function following flexor tendon repair in zone II: a comparison of immobilization and controlled passive motion techniques. Journal of Hand Surgery, 5A: 6: 53743. TAJIMA, T. (1984). History, current status, and aspects of hand surgery in Japan. Clinical Orthopaedics and Related Research, 184: 4149. URBANIAK, J. R., CAHILL, J. D. and MORTENSON, R. A. Tendon suturing methods: analysisoftensile strengths. In: American Academyoforthopaedic Surgeons. Symposium on Tendon Surgery in the Hand. St. Louis, C.V. Mosby, 1975: 70-80. WADE, P. J. F., MUIR, I. F. K. and HUTCHEON, L. L. (1986). Primarytlexor tendon repair: the mechanical limitations of the modified Kessler technique. Journal of Hand Surgery, 11B: 1: 71-76.
flexortendon
Accepted: 23 May 1991 Leonard Gordon, M.D., U.C.S.F. CA94143,U.S.A. 0 1992 The British
School of Medicine,
Society for Surgery
of the Hand
400 Pamassus,
Suite 636, San Francisco,