Callus formation during healing of the repaired tendon-bone junction

Abstract

This study was undertaken to elucidate the mechanism of biological repair at the tendon-bone junction in a rat model. The stump of the toe flexor tendon was sutured to a drilled hole in the tibia (tendon suture group, n = 23) to investigate healing of the tendon-bone junction both radiologically and histologically. Radiological and histological findings were compared with those observed in a sham control group where the bone alone was drilled (n = 19). The biomechanical strength of the repaired junction was confirmed by pull-out testing six weeks after surgery in four rats in the tendon suture group. Callus formation was observed at the site of repair in the tendon suture group, whereas in the sham group callus formation was minimal. During the pull-out test, the repaired tendon-bone junction did not fail because the musculotendinous junction always disrupted first. In order to understand the factors that influenced callus formation at the site of repair, four further groups were evaluated. The nature of the sutured tendon itself was investigated by analysing healing of a tendon stump after necrosis had been induced with liquid nitrogen in 16 cases. A proximal suture group (n = 16) and a partial tenotomy group (n = 16) were prepared to investigate the effects of biomechanical loading on the site of repair. Finally, a group where the periosteum had been excised at the site of repair (n = 16) was examined to study the role of the periosteum. These four groups showed less callus formation radiologically and histologically than did the tendon suture group. In conclusion, the sutured tendon-bone junction healed and achieved mechanical strength at six weeks after suturing, showing good local callus formation. The viability of the tendon stump, mechanical loading and intact periosteum were all found to be important factors for better callus formation at a repaired tendon-bone junction.

Repair of fresh patellar tendon rupture: tension regulation at the suture line

“…Hibino et al recorded radiographically good callus formation at the loaded tendon-bone junction by six weeks [6]. In this study, the callus was observed radiographically at the lower patellar pole by six weeks postoperatively (Fig.…”

“…c A radiograph was made at 12 weeks postoperatively; the patella has resumed its normal height and the callus at the tendon-bone junction appears more evident Fig. 4 Lateral view radiograph made 2 years postoperatively shows that the large callus at the lower patellar pole has increased the diagonal length of the patella to provide a false impression of patella baja, but the A/B ratio=0.85 6,16]. On the other hand, mechanical loading too early will only risk a failure of suture threads or permanently lengthen the tendon callus [1].…”

“…Therefore, healing of the avulsed tendon comprises healing of the tendinous tissue and tendon-bone junction. Lack of mechanical stimulation is detrimental to healing progress at both interfaces [1,4,6,[16][17][18].…”

“…By six weeks after surgery, the sutured tendon-bone junction achieved mechanical strength [6]. Therefore, a vigorous programme of straight leg rising with weights and active flexion exercise is instituted.…”

“…However, better healing is possible, but requires timely mechanical loading of the repaired tendon [1,4,6,9,[16][17][18]. According to current knowledge the appropriate time point during the healing process for loading to start has been identified [1,18], but there is a need to find a practical tool for initiation of the biomechanical loading.…”