Abstract

Introduction and Aims: Incidental dural tears and cerebrospinal fluid (CSF) leaks are common complications of spinal surgery. Collagen matrix (DuraGen, Integra LifeSciences) derived from bovine flexor tendons allows CSF absorption up to 100 times its weight without a volume change. Aim of this study was categorising the dural tears and monitoring post-operative complications.

Method: In this three-year prospective study, 35 patients (22 males, 13 females; mean age 53.8 years (range 16–82)) were selected by the following criteria: (1) any spine operation resulting in intra-operative CSF leak due to dural tear; or (2) persistent post-operative CSF leak. Collagen matrix was cut according to the extent of the dural defect (pinhole, < 1cm, 1–2 cm, and > 2cm). Dural matrix was moistened and applied as a graft and overlying tissues were meticulously reconstituted. Collagen sponge was not sutured on the dura. Subfascial drain was used at the discretion of surgeon to avoid hematoma and blood loss.

Results: The 39 procedures were as follows: 23 laminectomies, six diskectomies, four hematoma repairs, three structural repairs, two fracture stabilisations and one cystectomy. The locations of the 39 procedures were: 27 lumbar, seven thoracic, and five cervical. In 33 of 39 procedures, hemovac subfascial drain was used to avoid hematoma and excessive blood loss. Fibrin glue was used in two cases only. In 13 cases the dural defect was > 2cm, five cases 1–2cm, five cases < 2cm, and nine were pinhole defects. Of importance was the successful repair of 13 large dural tears (> 2cm) using the collagen sponge. Our study showed a 97.4% success rate for repairing dural tears using the collagen sponge surpassing the established techniques success rates by up to 10%. There were no wound infections post-operatively, versus the 6% rate of deep wound infection using the standard suture and fibrin glue. The mean follow-up time was 3.1 months. In two out of 39 procedures collagen sponge was used to repair persistent post-operative CSF leaks (no dural sponge used in the original operation).

Conclusion: Considering the technical challenge of dural tears, especially ventral or lateral tears, the use of collagen sponge offers an excellent alternative mini-mising a prolonged procedure, wound infection, use of tissue grafts, as well as excessive blood loss. This study showed collagen sponge to be effective as a permanent dural substitute.

Introduction and Aims: Severe Dupuytren’s contracture of the proximal interphalangeal (PIP) joint is a difficult condition to treat; a two-stage technique has been advocated by some surgeons for such cases. The present study set out to determine the early results of this technique.

Method: Thirteen patients (11 with primary and two with recurrent disease) with a severe Dupuytren’s contracture of the proximal interphalangeal (PIP) joint were treated by geometric correction (in line distraction followed by angular correction) using the OrthofixTM mini external fixator followed by its removal and partial fasciectomy (without collateral ligament or volar plate release). The mean duration of distraction was 14 days.

Results: In the PIP joint the mean true fixed flexion deformity pre-operatively was 75 degrees (range 45–90). At a mean follow-up of 21 months, the mean residual flexion deformity was 35 degrees (range 10–90). The mean arc of motion increased from 26 (range 10–55) to 51 degrees (range 0–90). At follow-up, the mean arc of motion was 33 degrees (range 0–70) and 73 degrees (range 45–110) at the distal interphalangeal and meta-carpophalangeal joints respectively. There were no cases of reflex sympathetic dystrophy or neurovascular damage. One patient had a fracture of the proximal phalanx and a second patient had an early recurrence, which led to a poor clinical outcome. The rest had an excellent clinical outcome according to the Michigan Hand Questionnaire.

Conclusion: Although the technique is challenging, the early results are promising and we recommend it for the management of this difficult problem.

The fourth lumbar vertebrae and L4-5 discs from six cadaveric lumbar spines were subjected to detailed strain gauge analysis under conditions of controlled loading. With central compression loads, maximal compressive strain was found to occur near the bases of the pedicles and on both superficial and deep surfaces of the pars interarticularis, which emphasises the importance of the posterior elements of lumbar vertebrae in transmitting load. Radial bulge and tangential strain of the disc wall were maximal at the posterolateral surface, in agreement with the fact that disc degeneration and prolapse commonly occur there. Under posterior offset loads simulating extension, both compressive and tensile strains were found to be increased on both surfaces of the pars interarticularis, which suggests that hyperextension may lead to stress fractures and spondylolisthesis. Posterior offset loads also increased the radial bulge of the posterior disc wall and tangential strain at the anterior surface of the disc. Anterior offset loads simulating flexion increased the radial bulge of the anterior disc wall and tangential strain at the posterior surface of the disc. These findings are compatible with movement of the nucleus pulposus within the disc during flexion and extension. This hypothesis was supported by post-mortem discography.