P. H. Robinson

Methods to evaluate functional nerve recovery in adult rats: walking track analysis, video analysis and the withdrawal reflex

The aim of this study was to compare different methods for the evaluation of functional nerve recovery. Three groups of adult male Wistar rats were studied. In group A, a 12-mm gap between nerve ends was bridged by an autologous nerve graft; in rats of group B we performed a crush lesion of the sciatic nerve and group C consisted of non-operated control rats. The withdrawal reflex, elicited by an electric stimulus, was used to evaluate the recovery of sensory nerve function. To investigate motor nerve recovery we analyzed the walking pattern. Three different methods were used to obtain data for footprint analysis: photographic paper with thickened film developer on the paws, normal white paper with finger paint, and video recordings. The footprints were used to calculate the sciatic function index (SFI). From the video recordings, we also analyzed stepcycles. The withdrawal reflex is a convenient and reproducible test for the evaluation of global sensory nerve recovery. Recording walking movements on video and the analysis of footplacing is a perfect although time-consuming method for the evaluation of functional aspects of motor nerve recovery.

Light-microscopic and electron-microscopic evaluation of short-term nerve regeneration using a biodegradable poly(DL-lactide-epsilon-caprolacton) nerve guide

The aim of this study was to evaluate short-term peripheral nerve regeneration across a 10-mm. gap, using a biodegradable poly(DL-lactide-epsilon-caprolacton) nerve guide, with an internal diameter of 1.5 mm and a wall thickness of 0.30 mm. To do so, we evaluated regenerating nerves using light microscopy, transmission electron microscopy and morphometric analysis after implantation of 12-mm nerve guides in the sciatic nerve of the rat. Evaluation times ranged from 3-10 weeks. Three weeks after reconstruction, myelinated nerve fibers could be observed in the distal nerve stump. Ten weeks after reconstruction, the regenerating nerves already resembled normal nerves. In conclusion, we show that poly(DL-lactide-epsilon-caprolacton) nerve guides can be successfully applied in the reconstruction of severed nerves in the rat model. Furthermore, we have observed the fastest nerve regeneration described thus far, after reconstruction using a biodegradable nerve guide.

Long-term evaluation of degradation and foreign-body reaction of subcutaneously implanted poly(DL-lactide-epsilon-caprolactone)

The aim of this study was to evaluate the degradation and foreign-body reaction of poly(DL-lactide-epsilon-caprolactone) (PLA85CL50) bars. This specific biomaterial is used for the construction of nerve guides, which can be used in the reconstruction of short nerve gaps. Subcutaneously implanted PLA85CL50 bars were harvested after implantation periods ranging from 3 to 12 months and evaluated for the rate of degradation and the degree of foreign-body reaction. It was observed that this copolymer degraded completely within 12 months and that no lactide or epsilon-caprolactone crystals were formed. Furthermore, we conclude that the foreign-body reaction of PLA85CL50 is very mild. These properties make the amorphous copolymer of DL-lactide and epsilon-caprolactone (50:50) suitable for the construction of nerve guides.

Poly(DL-lactide-epsilon-caprolactone) nerve guides perform better than autologous nerve grafts.

The aim of this study was to compare the speed and quality of nerve regeneration after reconstruction using a biodegradable nerve guide or an autologous nerve graft. We evaluated nerve regeneration using light microscopy, transmission electron microscopy and morphometric analysis. Nerve regeneration across a short nerve gap, after reconstruction using a biodegradable nerve guide, is faster and qualitatively better, when compared with nerve reconstruction using an autologous nerve graft. Therefore, we conclude that in the case of a short nerve gap (1 cm), reconstruction should be carried out using a biodegradable nerve guide constructed of a copolymer of DL‐lactide and ϵ‐caprolactone.

Functional assessment of sciatic nerve reconstruction: Biodegradable poly (DLLA-epsilon-CL) nerve guides versus autologous nerve grafts

The aim of this study was to compare functional nerve recovery after reconstruction with a biodegradable p(DLLA‐ϵ‐CL) nerve guide filled with modified denatured muscle tissue (MDMT), or an autologous nerve graft. We evaluated nerve recovery using walking track analysis (measurement of the sciatic function index [SFI]) and electrostimulation tests. Functional nerve recovery after reconstruction with a biodegradable p(DLLA‐ϵ‐CL) nerve guide filled with MDMT was faster when compared with nerve reconstruction using an autologous nerve graft. We conclude that in case of a short nerve gap in the rat, reconstruction can best be carried out using a p(DLLA‐ϵ‐CL) biodegradable nerve guide filled with MDMT.

In vivo and in vitro degradation of poly[50/50 (85/15L/D)LA/ε-CL], and the implications for the use in nerve reconstruction

Nerve guides can be used for the reconstruction of peripheral nerve defects. After serving their function, nerve guides should degrade. p[50/50 (85/15L/D)LA/e-CL] degrades completely within 1 year without the formation of a slow degrading crystalline fraction. Although the tensile strength (TS) of a p[50/50 (85/15L/D)LA/e-CL] nerve guide is negligible after 2 months, nerve regeneration across a 1-cm gap in the sciatic nerve of the rat is faster and qualitatively better than after reconstruction using autologous nerve grafts. During degradation p[50/50 (85/15L/D)LA/e-CL] swells, especially during the first 3 months. This can have a negative influence on the regenerating nerve. p[50/50 (85/15L/D)LA/e-CL] nerve guides could only be used in the clinical situation in case of short nerve gaps (several mm) in small nerves (for instance digital nerves). Refinements will be needed to successfully reconstruct longer nerve gaps (several cm).

Electronmicroscopical evaluation of short-term nerve regeneration through a thin-walled biodegradable poly(DLLA-epsilon-CL) nerve guide filled with modified denatured muscle tissue.

The aim of this study was to evaluate short-term peripheral nerve regeneration across a 15-mm gap in the sciatic nerve of the rat, using a thin-walled biodegradable poly(DL-lactide-epsilon-caprolactone) nerve guide filled with modified denatured muscle tissue (MDMT). The evaluation was performed using transmission electron microscopy and morphometric analysis. Evaluation times ranged from 3 to 12 weeks after reconstruction. Already, 3 weeks after reconstruction, myelinated nerve fibers could be observed in the distal nerve stump. Twelve weeks after reconstruction, the number of (non)myelinated nerve fibers had significantly increased in the distal nerve stump. From this study, we can conclude that a thin-walled biodegradable poly(DL-lactide-epsilon-caprolactone) nerve guides filled with MDMT can be successfully applied in the reconstruction of severed nerves in the rat model. Furthermore, we showed fast nerve regeneration across the 15-mm nerve gap and found that the use of MDMT functioned as a mechanical support preventing a collapse of this thin-walled nerve guide.

Evaluation of several techniques to modify denatured muscle tissue to obtain a scaffold for peripheral nerve regeneration

The aim of this study was to (1) evaluate the effect of several preparation techniques of denatured muscle tissue to obtain an open three-dimensional structure, and (2) test if this scaffold is suitable for peripheral nerve regeneration. Four samples (A-D) of muscle tissue specimens were evaluated using light microscopy, immunohistochemistry and cryo-scanning electron microscopy. Sample C showed the most open extracellular matrix, whilst collagen type IV and laminin (in the basal lamina) could still be observed using immunohistochemistry. An in vivo pilot study showed that the first signs of functional nerve recovery and axon regeneration could be observed after 3 weeks of implantation. We conclude that sample C has the most open structure and leads to good nerve regeneration and functional nerve recovery.

Long-term results of arthrodesis of the carpometacarpal joint of the thumb

We reviewed 48 arthrodeses of the carpometacarpal joint of the thumb in 39 patients being treated for osteoarthritis. The mean follow-up period was 90 months (range 14 months-17 years). In 28 (58%) hands pain relief was excellent and in 6 (12%) good. Mobility was significantly reduced ( p < 0.002). Mean key pinch (52.9 N) and grip strength (219.5 N) were comparable with the unoperated hand (51.0 and 239.1 N, respectively). Hand function was near normal. In 29 hands an additional operation was needed to remove the osteosynthesis material; 14 hands failed to unite. Osteoarthritis of the scaphotrapezial joint increased significantly faster in the operated hands than in the unoperated ones ( p < 0.0001). A soft tissue procedure (such as flexor carpi radialis interposition arthroplasty) is advised instead of arthrodesis, because of the large number of reoperations, based on non-union and removal of the osteosynthesis material. From a survey of published papers we conclude that arthrodesis of the carpometacarpal joint of the thumb can best be done by stapling and bone grafting.We reviewed 48 arthrodeses of the carpometacarpal joint of the thumb in 39 patients being treated for osteoarthritis. The mean follow-up period was 90 months (range 14 months-17 years). In 28 (58%) hands pain relief was excellent and in 6 (12%) good. Morbility was significantly reduced (p < 0.002). Mean key pinch (52.9 N) and grip strength (219.5 N) were comparable with the unoperated hand (51.0 and 239.1 N, respectively). Hand function was near normal. In 29 hands an additional operation was needed to remove the osteosynthesis material; 14 hands failed to unite. Osteoarthritis of the scaphotrapezial joint increased significantly faster in the operated hands than in the unoperated ones (p < 0.0001). A soft tissue procedure (such as flexor carpi radialis interposition arthroplasty) is advised instead of arthrodesis, because of the large number of reoperations, based on non-union and removal of the osteosynthesis material. From a survey of published papers we conclude that arthrodesis of the carpometacarpal joint of the thumb can best be done by stapling and bone grafting.

Poor results of distal trapezium resection for trapeziometacarpal-1 osteoarthritis

Abstract Eleven patients (mean age 54 years, range 46–67 years) with osteoarthritis limited to the trapeziometacarpal-1 joint underwent a distal trapezium resection. In nine cases the palmaris longus tendon and in two cases a Swanson condylar implant was used as interposition material. The results were very disappointing. Only one patient was satisfied. Nine patients were reoperated upon (mean interval period 43 months, range 3–110) because of pain. In two cases, the cause was dislocation of the Swanson condylar implant. In the other seven cases, prominent bone on the trapezium, ulnar osteophytes, scaphotrapezial osteoarthritis, sclerosis of the trapezium remnant, and impingement were causal factors. In future, the selection of patients for this operation will be performed with even greater care. Despite these poor results, a definitive conclusion about the indication for this procedure can only be made after evaluation of an improved operative procedure.