Qualitative analysis of substance P, NK1-receptor and nerve ingrowth in substance P-treated ruptured rat Achilles tendon

Substance P has a stimulating effect on fibroblast proliferation, collagen organization, and angiogenesis in ruptured and subsequently sutured rat Achilles tendon. This effect is also reflected in the biomechanical properties of the tendon. The aim of this study was to substantiate the effect of exogenous substance P on endogenous substance P, NK-1 receptor, and nerve ingrowth in an in vivo tendon-healing setting. Ninety-six male Sprague-Dawley rats were randomly assigned to one of four groups and injected with saline, substance P (10(-6) micromol/kg BW and 10(-8) micromol/kg BW) associated with neutral endopeptidase inhibitors, or neutral endopeptidase inhibitors alone into the paratendinous region of the ruptured and subsequently sutured Achilles tendons from the second until the sixth day postoperatively. Substance P, NK-1 receptor, and nerve ingrowth (PGP 9.5) were analysed using immunofluorescence at four different time points: one, two, four and six weeks postoperatively. In all groups substance P was predominantly expressed in the extracellular matrix during the first two weeks, corresponding to fibroblast proliferation, and first disappeared from the saline group in the proliferative phase. In contrast, substance P was not expressed in the blood vessel wall during the first two weeks, when angiogenesis was most pronounced. NK-1 receptor was almost always expressed in the blood vessel wall and in the extracellular matrix during this period and disappeared progressively afterwards. No nerve ingrowth was identified. Exogenously administered substance P in sutured rat Achilles tendon rupture does not stimulate sensory nerve ingrowth, but seems to have a booster effect on endogenous substance P for fibroblast proliferation via autocrine/paracrine stimulation.

Application of BMP-7 to tibial non-unions: a 3-year multicenter experience

The effective treatment of the often debilitating, longlasting and large-asset-consuming complication of fracture non-unions has been in the centre of scientific interest the last decades. The use of alternative bone substitutes to the gold standard of autologous graft includes the osteoinductive molecules named bone morphogenetic proteins (BMPs). A multicenter registry and database (bmpusergroup.co.uk) focused on the application of BMP-7/OP-1 was created in December 2005. We present the preliminary results, using the prospective case-series of aseptic tibial non-unions as an example. Sixty-eight patients fulfilled the inclusion criteria for this observational study, with a minimum follow-up of 12 months. The median duration of tibial non-union prior to BMP-7 application was 23 months (range 9-317 mo). Patients had undergone a median of 2 (range 0-11) revision procedures prior to the administration of BMP-7. In 41% the application of BMP-7 was combined with revision of the fixation at the non-union site. Non-union healing was verified in 61 (89.7%) in a median period of 6.5 months (range 3-15 mo). No adverse events or complications were associated with BMP-7 application. The safety and efficacy of BMP-7 was verified in our case series, and was comparable to the existing evidence. The establishment of multicenter networks and the systematic and long-term follow- up of these patients are expected to provide further information and significantly improve our understanding of this promising osteoinductive bone substitute.

Exogenously administered substance P and neutral endopeptidase inhibitors stimulate fibroblast proliferation, angiogenesis and collagen organization during Achilles tendon healing

BACKGROUND

In the last few years much research has been conducted in methods to promote tendon healing. The aim of this study was to determine if the healing process after operative repair of rat Achilles tendons could be stimulated by the paratendinous injection of a sensory peptide, substance P (SP).

METHODS

Ninety-six male Sprague-Dawley rats were randomly allocated to four groups: (I) control buffer injections, (II) injections of SP 10(-6) mol/kg body weight combined with a carrier, (III) injections of SP 10(-8) mol/kg BW with the carrier, and (IV) injections with the carrier only (thiorphan 1 micromol/kg BW and captopril 30 micromol/kg BW, both neutral endopeptidase inhibitors). The influence on tissue repair was determined from the histologic measurement of fibroblast proliferation, angiogenesis, and collagen organization. On days 7, 14, 28 and 42, animals were sacrificed and histologic evaluations were performed on the injured Achilles tendon constructs.

RESULTS

The two groups subjected to SP injections showed a significant initial fibroblast proliferation on day 7 (p < 0.05), which rapidly declined by day 14 to the level of cellular proliferation observed with the use of thiorphan and captopril. Capillary proliferation showed a similar evolution, except that in the second week angiogenesis in the treated groups was below the level of the control group. Strikingly, collagen orientation increased faster in the groups injected with SP. This was obvious from the second week already and the difference remained until the completion of the study.

CONCLUSION

This is the first study to demonstrate that paratendinous injections of SP after operative repair of the Achilles tendon in rats appears to provide a boost to the initial stages of healing and significantly accelerate the reparative phase of the healing process.

Influence of burst TENS stimulation on collagen formation after Achilles tendon suture in man. A histological evaluation with Movat's pentachrome stain

Retrograde or antidromic stimulation of the nociceptive C fibres is known to lead to the release of sensory neuropeptides, such as substance P (SP), by the peripheral endings of sensory unmyelinated C nerve fibres. These neuropeptides play a role in the healing of soft tissues. Burst TENS (Transcutaneous Electric Nerve Stimulation) is known to be most effective in influencing retrograde C fibre-evoked activity. This is why burst TENS was used in a randomised study as a stimulus for the healing of the sutured Achilles tendon in 9 patients, versus 9 others who received no stimulus. Originally, each group consisted of 10 patients, but there was a single drop-out in each group. Six weeks after surgery a needle biopsy sample was obtained, and stained with Movat's pentachrome stain. It showed a statistically significant influence of burst TENS on new collagen production, maturation of newly formed collagen and organisation of collagen. This suggests that burst TENS might positively influence healing of Achilles tendon suture in man.

Influence of burst TENS stimulation on the healing of Achilles tendon suture in man

Retrograde or antidromic stimulation of the nociceptive C fibres is known to lead to the release of sensory neuropeptides Substance P (SP) and Calcitonin Gene-Related Peptide (CGRP) by the peripheral endings of these ultra-thin nerve fibres. These neuropeptides have, among others, a vasodilatory effect, which explains why they play a role in the healing of soft tissues. Burst TENS (Transcutaneous Electric Nerve Stimulation) is known to be most effective in influencing C fibre-evoked activity. This is why burst TENS was used in a randomised study as a stimulus for the healing of the sutured Achilles tendon in 10 patients, versus 10 others who received no stimulus. There was one drop-out in each group, so that 2 x 9 patients remained available for the study. A needle biopsy, performed after six weeks, showed no significant influence of burst TENS on the histological healing stage, as compared with a rat study. However, a semi-quantitative evaluation of the number of fibroblasts showed a significant advantage for the stimulated group: p = 0.007. This means that burst TENS might influence healing of Achilles tendon sutures in man. But above all, it means that a histochemical study of the influence of burst TENS on the release of substance P and CGRP, after suture of the Achilles tendon in man, would be worthwhile.

Tibiocalcaneal Marchetti-Vicenzi nailing in revision arthrodesis for posttraumatic pseudarthrosis of the ankle

The authors conducted a retrospective study of 7 patients treated with tibiotalocalcaneal Marchetti-Vicenzi nailing (one anterograde and six retrograde nails). All these patients had developed pseudarthrosis after previous arthrodesis for posttraumatic ankle fractures. The results were evaluated clinically and radiographically at a median time of four years. Fusion occurred in three patients, in one of them only after removal of the proximal locking screw. Of the remaining four patients, one achieved consolidation after replacement of the Marchetti-Vicenzi nail by another intramedullary nail, two were lost to follow-up after replacement by external or internal fixation, and the last patient developed pseudarthrosis again. At least nine additional interventions were necessary in six patients, including one amputation for intractable pain and severe soft-tissue damage due to the trauma. None of the patients had excellent or good results. The majority was unsatisfied with this type of intramedullary nailing. Therefore our study was terminated prematurely. Revision ankle fusion for nonunion or malunion after external or internal fixation has a high complication rate. Further study is mandatory to prevent or resolve remaining problems.

[A comparative study of 2 treatment methods for onychocryptosis (ingrown toenail)]

One hundred and fifty-six patients, on whom 200 procedures for ingrowing toenails were performed, were randomly allocated into one or two treatment groups: segmental phenolization and wedge excision. There were 94 segmental phenolizations and 106 wedge excisions. Post-treatment discomfort was assessed on an analytical graph. There was a clear difference between the two groups one week after treatment. Over a mean follow-up period of 12 months a total of 27 nail spikes occurred, 8 in the phenolized group and 16 in the wedge excision group, this being not a significant difference at the five per cent level.