Effect of periosteal stripping on cortical bone perfusion: a laser doppler study in sheep

Labral Reconstruction via Capsular Augmentation Maintains Perfusion to the Acetabular Labrum and Locally Transferred Autograft: An in Vivo Laser Doppler Flowmetry Analysis

Background

The purpose of the present study was to examine the effects of arthroscopic labral repair with capsular augmentation on blood flow in vivo with use of laser Doppler flowmetry (LDF) to measure microvascular perfusion of the labrum and autograft tissue.

Methods

The present prospective case series included patients ≥18 years old who underwent arthroscopic acetabular labral repair with capsular augmentation; all procedures were performed by a single surgeon between 2018 and 2022. The LDF probe measured microvascular blood flow flux within 1 mm3 of the surrounding labral and capsular tissue of interest. Mean baseline measurements of flux were compared with readings immediately following capsular elevation and after completing labral augmentation. Blood flux changes were expressed as the percent change from the baseline measurements.

Results

The present study included 41 patients (24 men [58.5%] and 17 women [41.5%]) with a mean age (and standard deviation) of 31.3 ± 8.4 years, a mean BMI of 24.6 ± 3.4 kg/m2, a mean lateral center-edge of angle 35.3° ± 4.9°, a mean Tönnis angle of 5.8° ± 5.8°, and a mean arterial pressure of 93.7 ± 10.9 mm Hg. Following capsular elevation, the mean percent change in capsular blood flow flux was significantly different from baseline (-9.24% [95% confidence interval (CI), -18.1% to -0.04%]; p < 0.001). Following labral augmentation, the mean percent change in labral blood flow flux was significantly different from baseline both medially (-22.3% [95% CI, -32.7% to -11.9%]; p < 0.001) and laterally (-32.5% [95% CI, -41.5% to -23.6%]; p = 0.041). There was no significant difference between the changes in medial and lateral perfusion following repair (p = 0.136).

Conclusions

Labral repair with capsular augmentation sustains a reduced blood flow to the native labrum and capsular tissue at the time of fixation. The biological importance of this reduction is unknown, but these findings may serve as a benchmark for other labral preservation techniques and support future correlations with clinical outcomes.

Level of Evidence

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Osseous Union after Mandible Reconstruction with Fibula Free Flap Using Manually Bent Plates vs. Patient-Specific Implants: A Retrospective Analysis of 89 Patients

The aim of this monocentric, retrospective clinical study was to evaluate the status of osseous union in uni- and poly-segmental mandible reconstructions regarding conventional angle-stable manually bent osteosynthesis plates (Unilock 2.0 mm) versus titan laser-melted PSI patient-specific implant’s (PSI). The clinical impact of PSI’s high stiffness fixation methods on bone healing and regeneration is still not well addressed. The special interest was in evaluating the ossification of junctions between mandible and fibula and between osteotomized fibula free flap (FFF) segments. Panoramic radiograph (OPT), computed tomography (CT) scans, or cone-beam CTs (CBCT) of patients who underwent successful FFF for mandible reconstruction from January 2005 to December 2020 were analyzed. A total number of 89 cases (28 females (31.5%), 61 males (68.5%), mean age 58.2 ± 11.3 years, range: 22.8–82.7 years) fulfilled the chosen inclusion criteria for analysis (conventional: n = 44 vs. PSI: n = 45). The present study found an overall incomplete ossification (IOU) rate of 24.7% (conventional: 13.6% vs. PSI: 35.6%; p = 0.017) for mandible to fibula and intersegmental junctions. Between osteotomized FFF segments, an IOU rate of 16% was found in the PSI-group, while no IOU was recorded in the conventional group (p = 0.015). Significant differences were registered for IOU rates in poly-segmental (p = 0.041), and lateral (p = 0.016) mandibular reconstructions when PSI was used. Multivariate logistic regression analysis identified plate exposure and type of plate used as independent risk factors for IOU. Previous or adjuvant radiotherapy did not impact incomplete osseous union in the evaluated study sample. PSI is more rigid than bent mini-plates and shields functional mechanical stimuli, and is the main reason for increasing the rate of incomplete ossification. To enhance the functional stimulus for ossification it has to be discussed if patient-specific implants can be designed to be thinner, and should be divided into segmental plates. This directs chewing forces through the bone and improves physiological bone remodeling.

Osseointegration of a New, Ultrahydrophilic and Nanostructured Dental Implant Surface: A Comparative In Vivo Study

This study compared the osseointegration of acid-etched, ultrahydrophilic, micro- and nanostructured implant surfaces (ANU) with non-ultra-hydrophilic, microstructured (SA) and non-ultrahydrophilic, micro- and nanostructured implant surfaces (AN) in vivo. Fifty-four implants (n = 18 per group) were bilaterally inserted into the proximal tibia of New Zealand rabbits (n = 27). After 1, 2, and 4 weeks, bone-implant contact (BIC, %) in the cortical (cBIC) and spongious bone (sBIC), bone chamber ingrowth (BChI, %), and the supra-crestal, subperiosteal amount of newly formed bone, called percentage of linear bone fill (PLF, %), were analyzed. After one week, cBIC was significantly higher for AN and ANU when compared to SA (p = 0.01 and p = 0.005). PLF was significantly increased for ANU when compared to AN and SA (p = 0.022 and p = 0.025). After 2 weeks, cBIC was significantly higher in SA when compared to AN (p = 0.039) and after 4 weeks, no significant differences in any of the measured parameters were found anymore. Ultrahydrophilic implants initially improved osseointegration when compared to their non-ultrahydrophilic counterparts. In accordance, ultrahydrophilic implants might be appropriate in cases with a necessity for an accelerated and improved osseointegration, such as in critical size alveolar defects or an affected bone turnover.

Injectable in situ gelling delivery system for the treatment of jawbone infections

Aim: A polymeric in situ gelling delivery system for localized and sustained delivery to jawbone infections was developed. Materials & methods: In situ gelling delivery systems were prepared using either Poly(dl-lactic acid) or chitosan and Pluronic F127/Pluronic F68. Metronidazole nanoparticles were prepared using poly(dl-lactide-co-glycolide) or chitosan. Poly(dl-lactide-co-glycolide) was used for microparticles. Particles were characterized for size, charge and morphology. Results: Viscosity and yield stress of the gels were 0.4 Pa.s and 2 Pa, respectively, with 70% cell viability over 72 h. Around 90% of loaded metronidazole was released at a sustained rate over 1 week. Conclusion: Use of appropriate amount of nano/microparticles in the gel resulted in a sustained release over a period of 1 week - needed for jawbone infection.

Comparison of the wound-healing efficacy of gelatin sponge dressings and that of artificial dermis using atelocollagen in a rat cranial periosteal defect model

In oral surgery, tissue loss may occur in some cases, resulting in bone exposure and subsequent wound infection and possible scar formation during secondary healing. In this study, Terudermis^® Artificial Dermis (AD-T), a dermal defect graft made from processed bovine dermis collagen and gelatin sponge (GS) were used as dressings on 100-mm² wounds with exposed bone on the heads of rats. For the control group, the wound was left exposed. The wound-healing efficacy of the treatment was compared macroscopically and histologically among the three groups at 1, 2, and 4 weeks after surgery. Complete wound healing was achieved faster in the AD-T group than in the GS group, and osteoblasts appeared on the bone surface, indicating accelerated bone remodeling. Furthermore, in the AD-T group, there was an increased production of newly formed blood vessels, fibroblasts and osteoblasts positive for anti-cortactin antibodies, which are believed to contribute to wound healing. Our findings suggest that AD-T is better than GS as a wound dressing material.

Periosteum-Mimicking Tissue-Engineered Composite for Treating Periosteum Damage in Critical-Sized Bone Defects

The periosteum is an indispensable part of the bone that nourishes the cortical bone and acts as a repertoire of osteoprogenitor cells. Periosteal damage as a result of traumatic injuries, infections, or surgical assistance in bone surgeries is often associated with a high incidence of delayed bone healing (union or nonunion) compounded with severe pain and a risk of a secondary fracture. Developing bioengineered functional periosteal substitutes is an indispensable approach to augment bone healing. In this study, we have developed a biomimetic periosteum membrane consisting of electrospun oxygen-releasing antioxidant polyurethane on collagen membrane (polyurethane-ascorbic acid-calcium peroxide containing fibers on collagen (PUAOCC)). Further, to assist bone formation, we have developed a bioactive inorganic-organic composite cryogel (bioglass-collagen-gelatin-nanohydroxyapatite (BCGH)) as a bone substitute. In an in vitro simulated oxidative stress model, PUAOCC supported the primary periosteal cell survival. Moreover, in an in vivo, critical-sized (5.9 mm × 3.2 mm × 1.50 mm) unicortical rat tibial bone defect, implantation of PUAOCC along with the functionalized BCGH led to significant improvement in bone formation along with periosteal regeneration. The periosteal regeneration was confirmed by expression of periosteum-specific periostin and neuronal regulation-related protein markers. Our study demonstrates the development of a periosteum-mimicking membrane with promising applications to facilitate periosteal regeneration, thus assisting bone formation when used in combination with bone composites and mimicking the natural bone repair process.

Treatment options in femoral radiation fractures following soft tissue sarcoma: Incidence, risk factors, failures and flowchart of treatment

INTRODUCTION

The femur is the most frequent involved site by post-attinic fractures. The appropriate treatment of pathological fractures after radiotherapy is still controversial as they are associated with a high risk of delayed consolidation and non-union. Authors review a single Center series of pathological fractures after radiation therapy in patients affected by soft tissue sarcomas analyzing incidence, risk factors, failure rate and proposing a flow chart of treatment of postattinic fractures of the femur.

METHODS

Authors selected 570 patients treated by limb salvage surgery associated to radiation therapy from 1992 to 2018. A pathological fracture during follow up was observed in 28 cases (5%). The mean time between the onset of the fracture after the prior surgery + radiotherapy was 70 months (range 3-182). The mean follow-up from the fracture was 86 months (range 9-222).

RESULTS

The fracture treatment was performed with an intramedullary nail in 15 cases. Eight femoral fractures healed uneventfully (57%) and 6 required further surgical procedures. A total of eight patients underwent prosthetic replacement, 3 as a primary treatment and 5 as a salvage procedure after failure of internal fixation. Five patients developed a deep infection (62.5%).We observed 10 non-union (53%) in 19 patients treated with osteosynthesis. Overall amputation rate of the entire series was 18%. Authors propose a flowchart of treatment for femoral fractures.

CONCLUSION

Intramedullary nailing is the treatment of choice in postradiation diaphyseal fractures of long bones, prosthetic replacement in meta-epiphyseal fracture site. Free vascularized grafts remain a valid salvage solution after failure of internal fixation.

Periosteal and endosteal microcirculatory injury following excessive osteosynthesis

INTRODUCTION

We examined the endosteal and periosteal circulations in a patient with fracture non-union who had undergone excessive osteosynthesis applications (two long plates had been placed medially and laterally on the left tibia extending from the proximal 2/7 to the distal 6/7 parts of the bone, while a tibial component of a total knee prosthesis with a long stem had been inserted at the same time).

METHODS

Concomitant perfusion changes were determined in the anterolateral and anteromedial periosteal sheath of the non-united bone ends and intramedullary nearest the osteosynthesis materials during their surgical removal on re-operation. The blood flow in the periosteum and endosteum was recorded by a laser-Doppler flowmetric device using a novel approach. Control measurements were made at identical points of the right tibia.

RESULTS

Considerably lower blood flow values were measured along the tibial periosteal region of the re-operated limb than on the contralateral side (the average perfusion unit (PU) was 76 vs. 106 PU, respectively). Perfusion values were markedly lower in the endosteal region (average values of approx. 30 PU) in the control tibia and were even more diminished in the re-operated tibial endosteum (average 9 PU).

CONCLUSIONS

Our study was conducted to characterize the microcirculatory changes of a long bone in response to intramedullary implantation and to provide quantitative data on the insufficiency of local perfusion in a patient with fracture non-union. Our results highlight the association between local perfusion failure and the unfavorable outcome (i.e. fracture non-union), confirming that the vital aspects of the microcirculation should not be disregarded when aiming for mechanical stability. Microcirculatory measurements constitute a new area of improvement in planning the adequate treatment for fracture non-unions with an unclear aetiology. Further refinement of the laser-Doppler technique could have potential benefits for bone surgery and postoperative trauma care in the future.

Minimally invasive laser Doppler flowmetry is suitable for serial bone perfusion measurements in mice

In vivo laser Doppler flowmetry (LDF) has previously been used to quantify blood perfusion accurately at a single timepoint in the murine tibial metaphysis. However, this procedure entailed substantial disruption to soft tissues overlying the bone and caused notable localized inflammation for several weeks after the procedure, impeding serial measurements in the same mouse. In this study, we tested a less invasive technique to measure perfusion in the tibia with LDF and determined that it can be used serially in the same mouse without causing signs of inflammation or gait perturbations. Twenty 14-week-old C57Bl/6J mice were evenly divided into groups that either had daily treadmill exercise or remained sedentary. Within these activity groups, mice were evenly subdivided into groups that received LDF measurements either weekly or only once at the study endpoint. Bone perfusion was measured with LDF in the anteromedial region of the right tibial metaphysis. Serum concentrations of interleukin 6, incision site wound area, and interlimb coordination during gait were measured weekly for four weeks. Tibial perfusion did not differ significantly between exercise and sedentary groups within the weekly or endpoint-only LDF groups at any timepoint. Perfusion was significantly increased in the third week in the weekly LDF group relative to measurements in the second and fourth weeks. Ligation of the femoral artery caused consistent, rapid reductions in tibial perfusion, validating that LDF is sensitive to changes in tibial blood supply. Weekly LDF procedures did not adversely affect gait, as interlimb coordination during treadmill locomotion was similar between weekly and endpoint-only LDF groups at every timepoint. Images of the incision site show wound closure within one week, and serum concentrations of interleukin 6 were not significantly different between weekly and endpoint-only groups. Together, these findings demonstrate that our minimally invasive LDF technique is suitable for serial in vivo measurements of intraosseous blood perfusion without inducing localized inflammation or negatively affecting gait patterns in mice.

Effect of minimally invasive distal first metatarsal osteotomy on blood flow of the metatarsal head

BACKGROUND

Distal first metatarsal osteotomy is an option for operative treatment of mild to severe hallux valgus (HV) deformities. Minimally invasive distal linear metatarsal osteotomy (DLMO) provides good outcomes without avascular necrosis (AVN) of the metatarsal head. However, no reports have described the in vivo blood flow changes in the metatarsal head after osteotomy. This study was performed to evaluate the in vivo blood flow of the pre- and post-osteotomy metatarsal head in patients with HV using laser Doppler flowmetry and thus clarify the effect of minimally invasive distal first metatarsal osteotomy on the change in blood flow.

METHODS

From April 2015 to October 2016, DLMO was performed on 13 feet with HV in 10 patients (2 men, 8 women). Blood flow measurements of the pre- and post-osteotomy first metatarsal head in all feet were performed by laser Doppler flowmetry. AVN was evaluated using plain radiographs at the final postoperative follow-up.

RESULTS

The median pre- and post-osteotomy blood flow was 1.5 (0.97-1.95) and 1.46 (0.98-1.77) ml/min/100 g, respectively (median change in blood flow, 0.00; 95% CI, -0.23-0.13; P = 0.72). The rate of change in the blood flow was 0.0% (95% CI, -11.9%-8.7%; range, -28.6%-64.7%), and only three patients (23.1%) showed a decrease of ≥10%. The median pre- and post-osteotomy systolic blood pressure was 90 (84.5-97) and 93 (84.5-95) mmHg, respectively (median change in blood pressure, 0.00; 95% CI, -3.0-2.0; P = 0.82). The rate of change in the systolic blood pressure was 0.0% (95% CI, -3.1%-2.2%; range, -9.1%-24.0%). No radiographic evidence of AVN was present at the final follow-up.

CONCLUSIONS

No significant difference was found in the rate of change in blood flow pre- and post-osteotomy, suggesting that minimally invasive distal first metatarsal osteotomy does not influence blood flow of the metatarsal head.

Fractures after multimodality treatment of soft tissue sarcomas with isolated limb perfusion and radiation; likely to occur and hard to heal

OBJECTIVES

Treatment associated fractures (TAFs) are known severe side effects after surgery and radiotherapy for soft tissue sarcoma (STS). There is no literature about TAF after multimodality treatment with isolated limb perfusion (ILP) for locally advanced STS. This study aimed to analyze predictive factors, treatment and outcome for TAF after multimodality treatment with ILP.

METHOD

Out of 126 consecutive patients undergoing ILP after 1991 till now, 25 patients were excluded due to no surgery or direct amputation at initial surgery. Therefore, 101 patients were at risk and 12 developed a TAF (12%).

RESULTS

The majority of tumors was located at the upper leg and knee (N = 60), and 11 patients developed a TAF (18%) after median 28 (5-237) months. Twenty-five tumors were located at the lower leg, and 1 patient developed a TAF after 12 months (4%). No patients with a tumor at the upper extremities (N = 16) developed a TAF. Ten out of 12 patients with a fracture received adjuvant RT with a dose of 50 Gy, and a median boost dose of 18 (10-20) Gy. Predictive factors were periosteal stripping, age over 65 years at time of treatment and tumor size after ILP ≥10 cm. Multivariate analysis showed periosteal stripping and tumor size after ILP ≥10 cm as significant predictive factors. The majority of the fractures were treated with intramedullary nailing. Only one of 12 patients without radiotherapy reached bone union (8%). The median survival after developing TAF was 18 (1-195) months.

CONCLUSION

The overall risk of TAF after multimodality treatment with ILP was relatively high with 15% at ten years. The incidence of TAF for patients with tumors located at the thigh and knee after resection with periosteal stripping and radiotherapy was even >50%. The treatment of these fractures is challenging due to the high non-union rate, requiring an extensive orthopedic oncological TAF experience.

Quantitative analysis of the intramedullary arterial supply of the feline tibia

Objectives: To quantitatively describe the intramedullary arterial supply of the adult feline tibia and determine if the arterial supply is significantly different from that of adult small dogs.

Methods: Cadaveric feline and canine pelvic limbs were obtained to prospectively investigate the intramedullary arterial supply of the tibia. A microvascular injection and modified Spalteholz bone clearing technique were used to characterize and quantify the intramedullary arterial supply of the tibia. Statistical comparisons were made between cats and dogs for the percentage of intramedullary arterial supply (arterial density) and the diameter of the nutrient artery.

Results: No significant difference was observed in the intramedullary arterial density between dog and cat tibiae. The feline nutrient artery diameter (0.55 ± 0.1 mm) was significantly greater than the canine nutrient artery (0.30 ± 0.04 mm) in the distal section of bone. Dogs subjectively had a greater number of branching vessels in the distal and mid-diaphyseal sections of bone when compared to cats.

Clinical significance: Delayed fracture healing in the feline tibia does not appear to be associated with a lack of intramedullary arterial supply. A lack of diffuse arborization of the arterial supply to the middle and distal feline tibia may explain, at least in part, why feline tibial delayed or nonunions may be more common than in canine tibial fractures.

Pre-augmentation soft tissue expansion improves scaffold-based vertical bone regeneration - a randomized study in dogs

OBJECTIVE

Soft tissue (ST) dehiscence with graft exposure is a frequent complication of vertical augmentation. Flap dehiscence is caused by failure to achieve tension-free primary wound closure and by the impairment of flap microcirculation due to surgical trauma. Soft tissue expansion (STE) increases ST quality and quantity prior to reconstructive surgery. We hypothesized that flap preconditioning using STE would reduce the incidence of ST complications after bone augmentation and that optimized ST healing would improve the outcome of bone regeneration.

MATERIALS AND METHODS

Self-filling tissue expanders were implanted in mandibular bone defects in ten beagle dogs. After expansion, alloplastic scaffolds were placed for vertical bone augmentation in STE sites and in control sites without STE pre-treatment. ST flap microcirculation was analysed using laser Doppler flowmetry. The incidence of graft exposures was evaluated after 2 weeks. Bone formation was assessed after 2 months, using histomorphometry and immunohistochemistry.

RESULTS

Test sites showed significantly less impairment of perfusion and faster recovery of microcirculation after bone augmentation. Furthermore, no flap dehiscences occurred in STE sites. Bone regeneration was found in both groups; however, significantly greater formation of new bone was detected in test sites with preceding STE.

CONCLUSIONS

Preconditioning using STE improved ST healing and bone formation after vertical augmentation. The combination of STE and the subsequent placement of alloplastic scaffolds may facilitate the reconstruction of severe bone defects.

Comparison of the wound healing efficacy of polyglycolic acid sheets with fibrin glue and gelatin sponge dressings in a rat cranial periosteal defect model

Oral surgical procedures occasionally require removal of the periosteum due to lesions, and these raw bone surfaces are prone not only to infection but also to scar formation during secondary healing. The objective of this study was to identify successful methods for reconstruction using periosteal defect dressings. We created 1-cm2 defects in the skin and cranial periosteum of 10-week-old male Wistar rats under isoflurane anesthesia. The animals were assigned to three defect treatment groups: (1) polyglycolic acid sheets with fibrin glue dressing (PGA-FG), (2) Spongel® gelatin sponge dressing (GS), and (3) open wound (control). Postoperative wound healing was histologically evaluated at 2, 4, and 6 weeks. The moist conditions maintained by the GS and PGA-FG treatments protected the bone surface from the destructive effects of drying and infection. Complete wound healing was observed in the GS group but not for all animals in the PGA-FG and control groups. Histologically, osteoblast proliferation on bone surfaces and complete epithelialization with adnexa were observed in the GS group at 6 weeks after surgery. In contrast, PGA sheets that had not been absorbed inhibited osteoblast proliferation and delayed wound healing in the PGA-FG group. Wound surface dressings maintain a moist environment that promotes wound healing, but PGA materials may not be suitable for cases involving exposed periosteum or bone surfaces due to the observed scar formation and foreign-body reaction.

Reducing damage to the periosteal capillary network caused by internal fixation plating: An experimental study

BACKGROUND

The importance of the periosteum in fracture healing is well-known. Preserving periosteal vascularisation is essential during internal plate fixation of fractures.

METHODS

This was an experimental randomised, controlled animal study on nine sheep. Standard dynamic compression plate (DCP) and four different newly designed reefed plates, with different plate-bone contact surface areas and different reef directions, were fixated on to the tibia or radius. After two weeks the plates were removed and the underlying periosteum was analysed. Blood vessels were marked by immunohistochemical staining (CD31 and CD34), microphotographs were taken and blood vessels counted to calculate blood vessel density.

RESULTS

Median blood vessel density beneath the standard plate was significantly lower than in the intact periosteum (18.0 vs 27.7mm(3)/cm(3)). Blood vessel density in the periosteum beneath plates with reefs was significantly increased compared with the intact periosteum, and was highest beneath the plate with the lowest bone-plate contact area and crosswise reefs (51.5mm(3)/cm(3)), followed by plates with transverse, oblique and longitudinal reefs, respectively. The direction of the reefs did not have much influence on the periosteal capillary network. Lower contact surface area seems to be the main factor that increases blood vessel density beneath the plates.

CONCLUSIONS

The results show that plates with lower contact surface area stimulate angiogenesis in the underlying periosteum, which results in much higher blood vessel density compared with standard DCP. A randomised clinical trial is needed to prove the clinical relevance of these findings.

Pre-augmentation soft tissue expansion: an overview

OBJECTIVES

The aim of this study was to explore the development of soft tissue expanders, their different types and their potential applications prior to bone augmentation and implant placement.

MATERIAL AND METHODS

A review of pertinent literature was performed using PubMed to comprehend the dynamics of soft tissue expanders and determine the current position of their pre-augmentation applications.

RESULTS

There is promising, albeit preliminary information regarding the benefits of pre-augmentation soft tissue expansion. Findings cannot be generalised due to relatively small sample size.

CONCLUSIONS

Further clinical trials with larger sample sizes and long-term follow-up are needed before soft tissue expanders can be confidently applied in everyday clinical practice.

Effects of a new piezoelectric device on periosteal microcirculation after subperiosteal preparation

INTRODUCTION

Subperiosteal preparation using a periosteal elevator leads to disturbances of local periosteal microcirculation. Soft-tissue damage can usually be considerably reduced using piezoelectric technology. For this reason, we investigated the effects of a novel piezoelectric device on local periosteal microcirculation and compared this approach with the conventional preparation of the periosteum using a periosteal elevator.

MATERIAL AND METHODS

A total of 20 Lewis rats were randomly assigned to one of two groups. Subperiosteal preparation was performed using either a piezoelectric device or a periosteal elevator. Intravital microscopy was performed immediately after the procedure as well as three and eight days postoperatively. Statistical analysis of microcirculatory parameters was performed offline using analysis of variance (ANOVA) on ranks (p<0.05).

RESULTS

At all time points investigated, intravital microscopy demonstrated significantly higher levels of periosteal perfusion in the group of rats that underwent piezosurgery than in the group of rats that underwent treatment with a periosteal elevator.

CONCLUSION

The use of a piezoelectric device for subperiosteal preparation is associated with better periosteal microcirculation than the use of a conventional periosteal elevator. As a result, piezoelectric devices can be expected to have a positive effect on bone metabolism.

[Experimental studies of microcirculatory changes in the bone]

INTRODUCTION/AIMS

Our aim was to characterize the periosteal microvascular reaction induced by the destruction of endosteal vasculature by reaming, and to monitor the time sequence of the events. We have also compared the microcirculatory effects of different implant materials that are most frequently employed in human endoprosthetics.

MATERIALS AND METHODS

The right tibia of male Wistar rats was reamed by microsurgical means and implanted with titanium, steel-alloy or polyethylene nails. Intravital videomicroscopic examinations of the anteromedial and anterolateral surfaces of the tibial periosteum were performed to evaluate the changes in the overall vascular and capillary densities. Microscopic mechanical tests were used to assess the stability of the implants. In control groups, reaming without nailing was performed and the microvascular changes were examined 6 and 12 weeks after surgery.

RESULTS

Reaming alone caused a significant increase in the vascular density of the anteromedial periosteum and a bilateral increase in capillary density. Vascular density at the anteromedial side was increased after all of the implant materials applied, while only polyethylene induced remarkable increases in the capillary and vascular densities at the anterolateral side. Furthermore, polyethylene did not bring about osseointegration.

CONCLUSIONS

Enhanced periosteal angiogenesis could be demonstrated after 12 weeks following tibial reaming. The compensatory microvascular reactions evoked by destruction of endosteal microcirculation of long bones are not influenced by osseo-integrative implant materials, but materials of poor osseointegration properties induce considerable compensatory increases in the microvascular density of the periosteum.

Effects of extensive circumferential periosteal stripping on the microstructure and mechanical properties of the murine femoral cortex

Extensive periosteal stripping (PS) is a risk factor for post-radiation pathologic fracture following surgery for extremity soft tissue tumors. The purpose of this study was to determine the effects of PS on bone structure and mechanical properties. Thirty-one skeletally mature mice underwent PS, with circumferential removal of periosteum from an 8-mm segment of the mid-diaphysis of the left femur. Thirty-one control mice underwent sham surgery in which the femur was isolated without manipulation of the periosteum. At 2, 6, 12, or 26 weeks following surgery, the left femora were examined by micro-CT to quantify cortical thickness (CtTh), cross-sectional area (CSA), bone volume (BV), and polar moment of inertia (PMI). Three-point mechanical bend testing was performed and peak load, stiffness, and energy to failure were determined. PS resulted in significantly decreased CtTh, CSA, BV, and PMI at all time points. Peak load, stiffness, and energy to failure were significantly reduced at 2, 6, and 12 weeks. There were no significant differences in mechanical properties at 26 weeks. In this mouse model, extensive circumferential PS resulted in sustained changes in bone structure that were still evident after 6 months, accompanied by reductions in bone strength that persisted for at least 3 months.

Increase in periosteal angiogenesis through heat shock conditioning

Objective

It is widely known that stress conditioning can protect microcirculation and induce the release of vasoactive factors for a period of several hours. Little, however, is known about the long-term effects of stress conditioning on microcirculation, especially on the microcirculation of the periosteum of the calvaria. For this reason, we used intravital fluorescence microscopy to investigate the effects of heat shock priming on the microcirculation of the periosteum over a period of several days.

Methods

Fifty-two Lewis rats were randomized into eight groups. Six groups underwent heat shock priming of the periosteum of the calvaria at 42.5°C, two of them (n = 8) for 15 minutes, two (n = 8) for 25 minutes and two (n = 8) for 35 minutes. After 24 hours, a periosteal chamber was implanted into the heads of the animals of one of each of the two groups mentioned above. Microcirculation and inflammatory responses were studied repeatedly over a period of 14 days using intravital fluorescence microscopy. The expression of heat shock protein (HSP) 70 was examined by immunohistochemistry in three further groups 24 hours after a 15-minute (n = 5), a 25-minute (n = 5) or a 35-minute (n = 5) heat shock treatment. Two groups that did not undergo priming were used as controls. One control group (n = 8) was investigated by intravital microscopy and the other (n = 5) by immunohistochemistry.

Results

During the entire observation period of 14 days, the periosteal chambers revealed physiological microcirculation of the periosteum of the calvaria without perfusion failures. A significant (p < 0.05) and continuous increase in functional capillary density was noted from day 5 to day 14 after 25-minute heat shock priming. Whereas a 15-minute exposure did not lead to an increase in functional capillary density, 35-minute priming caused a significant but reversible perfusion failure in capillaries. Non-perfused capillaries in the 35-minute treatment group were reperfused by day 10. Immunohistochemistry demonstrated an increase in cytoprotective HSP70 expression in the periosteum after a 15-minute and a 35-minute heat shock pretreatment when compared with the control group. The level of HSP70 expression that was measured in the periosteum after 25 minutes of treatment was significantly higher than the levels observed after 15 or 35 minutes of heat shock exposure.

Conclusion

A few days after heat shock priming over an appropriate period of time, a continuous increase in functional capillary density is seen in the periosteum of the calvaria. This increase in perfusion appears to be the result of the induction of angiogenesis.

A technique for treating patello-femoral instability in immature patients: the tibial tubercle periosteum transfer

Patello-femoral problems are frequently encountered in knee clinic. The most important role of the patella is to increase the quadriceps efficiency, although this function could be altered in the patello-femoral instability. Active stability of the patello-femoral joint is provided by the surrounding muscles and ligaments, passive stability is provided by the bony and cartilage structures. Patellofemoral instability is defined, from Henry Dejour, as a disease without engagement the patella in the femoral trochlea during knee range of motion. Every time should be performed careful radiological preoperative investigations (radiographs and computed tomography) involving an expert musculoskeletal radiologist. Surgical procedures may be divided into those that address the soft tissues (muscles and ligaments), generally on the immature skeletal, and those that effect bony changes, generally on the mature skeletal; sometimes, it is necessary to combine soft-tissue and bony procedures. In this report, the authors describe a tibial tubercle periosteum transfer technique for patello-femoral instability in immature patients, which may potentially improve clinical results in very young symptomatic patients with patello-femoral instability.

Intravital microscopic studies of angiogenesis during bone defect healing in mice calvaria

PURPOSE

Due to the great availability of specific antibodies, gene-targeted animals and knockout strains, mouse models came into the focus of musculoskeletal research. Herein, we introduce a calvarian defect model in mice that allows the repetitive analysis of blood vessel formation during bone repair by intravital microscopy.

METHODS

The right parietal calvaria of 20 adult CD-1 mice were exposed by skin excision. Under continuous irrigation, a circular defect (Ø0.75 mm) was drilled into the calvarium without penetrating the inner cortical shell. A circular glass (Ø12 mm; thickness 0.15 mm) was fixed by two microscrews (M1; length 2mm) to cover the bone defect. Angiogenesis was analysed by intravital microscopy at days 0, 3, 6, 9, 12, 15, 18 and 21. In addition, bone repair was evaluated by histomorphometry at days 3, 6, 9 and 15. Immunohistochemical stainings for the angiogenic growth factor vascular endothelial growth factor (VEGF) and the cell proliferation marker proliferating cell nuclear antigen (PCNA) were performed to assess angiogenic and proliferative activity during healing of the calvarian defect.

RESULTS

Histomorphometry showed a typical pattern of intramembranous bone repair. Osseous bridging of the defect was observed at day 9. This was associated with the formation of a neo-periosteum, which covered the new woven bone and contained a dense network of newly formed blood vessels. At day 9, particularly cells of the neo-periosteum showed intense staining for VEGF, whilst PCNA-positive staining was found mainly in osteoblasts. At day 15, the major fraction of fibrous tissue was replaced by bone undergoing extensive remodelling. Intravital microscopy revealed an increase of vascular density between days 3 and 15. Blood vessel diameters showed an increase between days 3 and 9 and a subsequent decrease between days 9 and 21.

CONCLUSIONS

The present calvarian defect model provides a powerful tool to evaluate the process of angiogenesis during intramembranous bone repair in mice.

Unreamed or RIA reamed nailing: an experimental sheep study using comparative histological assessment of affected bone tissue in an acute fracture model

The purpose of the present study was to evaluate the Reamer/Irrigator/Aspirator (RIA), a reaming system designed to incorporate the advantages of irrigation and suction for every day clinical use. The evaluation process was focused on the displacement of the medullary content and its impact on cortical perfusion. The results of the RIA reamed nailing were compared to conventional non-reamed nailing (NRN). The tibia of the sheep was used as an acute fracture model. The fracture and nailing procedure was followed by intravital staining with Procion red. The effects on cortical perfusion (Procion red staining) were addressed in polymer embedded sections and cryosections. Sudan III stained cryosections were evaluated with respect to the cortical fat distribution. After irrigation and suction minute amounts of fat were observed in the cortex, whereas after non-reamed nailing the endosteal third of the cortical bone was penetrated with fat. Non-reamed nailing acutely showed better perfusion in the endosteal tenth and periosteal third of the cortical bone, after irrigation and suction reaming perfusion was preserved to a lesser degree. Irrigation and suction significantly reduces fat intravasation, and thus the danger of system-wide damage. Therefore, the Reamer/Irrigator/Aspirator is as efficient as its experimental predecessors.

Micro-computed tomography and histologic evaluation of the interface of hydrogel expander and underlying bone: influence of pressure distributors on bone resorption

PURPOSE

Tissue expanders lead to changes in the underlying bone and can cause bone resorption. We investigated whether the insertion of mechanical devices that distribute the load on the bone can influence these effects.

MATERIALS AND METHODS

A total of 28 Lewis rats were assigned to 1 of 4 groups. Hydrogel expanders were placed subcutaneously either directly on the calvaria, on titanium mesh, or on a titanium plate. The fourth group of rats served as the controls. The bone quality and thickness were assessed beneath, and at the periphery of, the expanders using micro-computed tomography and histologic examination.

RESULTS

Micro-computed tomography images were obtained before and 21 days after insertion. The images revealed a significant decrease in hydroxyapatite density beneath the expanders in the group with only expanders. This decrease was reduced with the use of titanium mesh and completely prevented with the use of titanium plates. Histologic examination revealed a significant decrease in bone density and marked lacunae beneath the hydrogel expanders in the group with only expanders. In contrast, the titanium mesh decreased the size of the lacunae, and the titanium plates completely prevented both the formation of lacunae and the decrease in bone thickness.

CONCLUSION

The bone resorption caused by hydrogel expanders can be diminished using titanium mesh and completely prevented by the insertion of a titanium plate.

Bone augmentation after soft-tissue expansion using hydrogel expanders: effects on microcirculation and osseointegration

OBJECTIVES

The success of bone augmentation, for example of the alveolar ridge, might be endangered by dehiscence of the soft tissue that covers the augmented bone. Soft-tissue coverage can be achieved without tension through pre-augmentation tissue expansion with hydrogel expanders. We used a periosteal chamber to study the influence of tissue expansion on microcirculation and osseointegration in an in vivo animal model.

MATERIAL AND METHODS

Sixteen isogeneic Lewis rats were randomised into two groups. Additional eight animals served as donors of isogeneic bone grafts (Group 3, n=8). The bone grafts were harvested and implanted into Group 1 animals (n=8) (without tissue expansion) and Group 2 animals (after tissue expansion). In Group 2 (n=8), hydrogel expanders were inserted subperiosteally at the site to be augmented for 21 days. We used intravital microscopy to monitor microcirculation in vivo for 19 days after implantation. Specimens from both groups were evaluated histologically.

RESULTS

During the entire study period, functional microvessel density in the region above the augmentation material was significantly higher after previous tissue expansion (P>0.05). Both groups showed physiological microcirculation around the augmentation material. Histology revealed bone osseointegration of the bone graft in the group with tissue expansion and the presence of connective and granulation tissue in the group without tissue expansion.

CONCLUSIONS

Pre-augmentation soft-tissue expansion with hydrogel expanders leads to higher functional microvessel density in the tissue above the augmentation material and thus, to more rapid osseointegration. The use of hydrogel expanders appears to increase the probability of success, especially of pre-implant bone augmentation.

Angiogenic factor-enriched platelet-rich plasma enhances in vivo bone formation around alloplastic graft material

PURPOSE

Although most researchers agree that platelet-rich plasma (PRP) is a good source of autogenous growth factors, its effect on bone regeneration is still controversial. The purpose of this study was to evaluate whether increasing angiogenic factors in the human PRP to enhance new bone formation through rapid angiogenesis.

MATERIAL AND METHODS

In vitro, the human platelets were activated with application of shear stress, 20 µg/ml collagen, 2 mM CaCl(2) and 10U thrombin/1 × 10(9) platelets. Level of vascular endothelial growth factor (VEGF) and platelet microparticle (PMP) in the activated platelets were checked. In the animal study, human angiogenic factors-enriched PRP was tested in 28 athymic rat's cranial critical bone defects with β-TCP. Angiogenesis and osteogenesis were evaluated by laser Doppler perfusion imaging, histology, dual energy X-ray densinometry, and micro-computed tomography.

RESULTS

In vitro, this human angiogenic factors-enriched PRP resulted in better cellular proliferation and osteogenic differentiation. In vivo, increasing angiogenic potential of the PRP showed significantly higher blood perfusion around the defect and enhanced new bone formation around acellular bone graft material.

CONCLUSION

Angiogenic factor-enriched PRP leads to faster and more extensive new bone formation in the critical size bone defect. The results implicate that rapid angiogenesis in the initial healing period by PRP could be supposed as a way to overcome short term effect of the rapid angiogenesis.

Intraosseous blood flow of the everted or laterally-retracted patella during total knee arthroplasty

Patellofemoral problems are relatively common sequelae of total knee arthroplasty (TKA), and many factors contribute to these complications. Vascular compromise has been identified as a possible contributing factor, and was selected for further investigation in the present study. Laser Doppler Flowmetry was used to quantify patella intraosseous blood flow in vivo during TKA surgery without the use of a tourniquet. Flow was measured after medial parapatellar arthrotomy, and compared to flow during patella eversion and lateral retraction. Patella blood flow during eversion was reduced to 13% of baseline values (p<0.05). A significantly greater proportion of flow was preserved during lateral retraction (53%), although the reduction from baseline was still significant (p<0.05). A statistically significant difference in flow (60% of baseline) was also noted when the leg was flexed from full extension to 90 degrees (p<0.05) with the patella in its normal anatomical alignment. In this study, we have demonstrated the sensitivity of the patella blood supply to knee flexion angle and patella dislocation technique, particularly to patella eversion. These may be important findings with regard to surgical technique for TKA.

Tibial tubercle transfer on a medial periosteal pedicle--a report of a new technique

Tibial tubercle transfer is still probably the most widely used procedure of the numerous operative procedures described to realign the patella and extensor mechanism and to prevent a recurrent dislocation. Although this procedure most likely disturbs the blood supply to the tibial tubercle and thus may lead to a delayed union. Tibial tubercle transfer is also considered to play a role in the incidence of a tibial tubercle delayed union. Furthermore, a fracture of the tibial metaphysis has been reported to occur in some cases. We therefore devised a new procedure in which the periosteum of the medial side of the proximal portion of the tibia was left intact when tibial tubercle transfer is performed. The current paper describes the results of new technique in 25 knees with patellar maltracking. Eighty-four percent of the patients had good or excellent results at a mean follow-up time of 49 months. All of the patients achieved complete healing radiographically within 2 months after the operation. Serious complications such as compartment syndrome, infection and skin slough were also completely avoided in all cases. This new procedure that the use of a protective maneuver for the periosteum of the medial side of the tibia may thus reduce the incidence of a delayed union and thereby promote early postoperative rehabilitation after tibial tubercle transfer.

Patella intraosseous blood flow disturbance during a medial or lateral arthrotomy in total knee arthroplasty: a laser Doppler flowmetry study

Patella complications are recognized sequelae of total knee arthroplasty (TKA). Disruption of blood flow to the patella and adjacent soft tissues during surgery may contribute to reduced viability of the bone and patella ligament tissue. The effect on genicular blood flow to the medial and lateral patella was compared for a medial (MA) and lateral arthrotomy (LA) during TKA. Laser Doppler flowmetry was used to measure both baseline and postarthrotomy flow in vivo for 16 primary TKA patients. Flow in the lateral patella was reduced approximately 20% for both MA and LA. Conversely, the use of MA resulted in substantial reduction in flow to the medial patella (53%) compared to the lateral approach (27%). A large standard deviation of scores was evident in all cases. Although there was a tendency for LA to disturb the patellar blood flow less, the difference was not significant. It was concluded that neither approach is superior regarding the blood flow preservation to the patella. Hence, a lateral approach might only have an advantage in knee joints that are likely to need a lateral release in combination with an MA-e.g., a valgus deformity or preoperative patella maltracking.

Complications of combined modality treatment of primary lower extremity soft-tissue sarcomas

BACKGROUND

Correlations between various patient, tumor, and treatment characteristics and complications in patients undergoing combined modality treatment for primary lower extremity soft-tissue sarcomas were investigated.

METHODS

Using the M. D. Anderson Radiation Oncology database, the records of the subset of patients treated with combined radiation and limb-sparing surgery for primary lower extremity soft-tissue sarcomas were retrospectively reviewed from the years 1960 to 2003.

RESULTS

In all, 412 patients were identified. With a median follow-up of 9.3 years, there were a total of 113 (27%) acute wound complications and 41 (13% at 20 years) chronic radiation-related limb complications. Preoperative radiation and tumor sizes >5 cm were associated with an increased risk of acute wound complications (34% preoperative vs. 16% postoperative, P < .001; and 31% >5 cm vs. 17% < or =5 cm, P = .005). At 20 years the radiation-related complication rate was higher in patients with a groin or thigh tumor location (16% vs. 4% other; P = .008), prior acute wound complications (20% vs. 10% no surgical complication), and a radiation dose > or =60 grays (Gy) (18% vs. 9% for dose < 60 Gy; P = .04). Five fractures occurred, resulting in a crude overall fracture rate of 1.2%.

CONCLUSIONS

Patients treated with preoperative radiation for larger tumors are more likely to have acute surgical wound complications. Acute wound complications followed by postoperative radiation are associated with chronic radiation-related limb problems, as are higher radiation dose and proximal tumor location. The fracture rate is so low that prophylactic fixation is not warranted.

Femur window--a new approach to microcirculation of living bone in situ

BACKGROUND

The processes of osteogenesis, bone remodelling, fracture repair and metastasis to bone are determined by complex sequential interactions involving cellular and microcirculatory parameters. Consequently studies targeting the analysis of microcirculatory parameters on such processes should mostly respect these complex conditions. However these conditions could not yet be achieved in vitro and therefore techniques that allow a long-term observation of functional and structural parameters of microcirculation in bone in vivo at a high spatial resolution are needed to monitor dynamic events, such as fracture healing, bone remodelling and tumor metastasis.

METHODS

We developed a bone chamber implant (femur window) for long-term intravital microscopy of pre-existing bone and its microcirculation at an orthotopic site in mice preserving the mechanical properties of bone. After bone chamber implantation vascular density, vessel diameter, vessel perfusion, vascular permeability and leukocyte-endothelial interactions (LEIs) in femoral bone tissue of c57-black mice (n=11) were measured quantitatively over 12 days using intravital fluorescence microscopy. Furthermore a model for bone defect healing and bone metastasis in the femur window was tested.

RESULTS

Microvascular permeability and LEIs showed initially high values after chamber implantation followed by a significant decrease to a steady state at day 6 and 12, whereas structural parameters remained unaltered. Bone defect healing and tumor growth was observed over 12 and 90 days respectively.

CONCLUSION

The new femur window design allows a long-term analysis of structural and functional properties of bone and its microcirculation quantitatively at a high spatial resolution. Altered functional parameters of microcirculation after surgical procedures and their time dependent return to a steady state underline the necessity of long-term observations to achieve unaltered microcirculatory parameters. Dissection of the complex interactions between bone and microcirculation enables us to evaluate physiological and pathological processes of bone and may give new insights especially in dynamic events e.g. fracture healing, bone remodeling and tumor metastasis.

Successful Treatment of Buerger's Disease with Intramedullary K-wire: The Results of the First 11 Extremities

OBJECTIVE

This study describes a new technique for treatment of Buerger's disease, developed to stimulate angiogenesis, using a Kirschner wire placed in the medullary canal of the tibia. The aim of the study was to evaluate clinical and radiological effects of this technique in patients where medical and surgical therapy had failed.

MATERIAL AND METHODS

Eleven extremities (six patients) with Buerger's disease were treated with the intramedullary Kirschner wire technique. Inclusion criteria were chronic critical ischemia, Rutherford Grade II or III, with major arterial occlusion shown by Doppler examination and angiography; failure to respond to non-surgical and surgical treatment; and the need for strong analgesics.

RESULTS

The mean follow-up time was 19 months (range, 13-25 months). Satisfactory remission in each patient was obtained within 6 weeks of intervention. A significant improvement in clinical manifestations including reduced rest pain and increased claudication distance was observed. Foot ulcers completely healed after Kirschner wire intervention.

CONCLUSION

Despite short-term follow-up and small patient series, the intramedullary Kirschner wire technique can be expected to achieve relief of pain and a decrease in major amputations in patients with Buerger's disease in whom medical and surgical therapy had failed. However, comparative studies with longer follow-up should be done to confirm the benefits of this new treatment.

Development of an atrophic nonunion model and comparison to a closed healing fracture in rat femur

Although most fractures heal, some fail to heal and become nonunions. Many animal models have been developed to study problems of fracture healing. The majority of nonunion models have involved segmental bone defects, but this may not adequately represent the biologic condition in which nonunions clinically develop. The objective of the present study is to develop a nonunion model that better simulates the clinical situation in which there is soft tissue damage including periosteal disruption and to compare this model to a standard closed fracture model utilizing identical fracture stabilization, providing a similar mechanical environment. A total of 96 three month old Long Evans rats were utilized. A 1.25 mm diameter K-wire was inserted into the femur in a retrograde fashion, and a mid-diaphyseal closed transverse fracture was created using a standard three-point bending device. To create a nonunion, 48 of the rats received additional surgery to the fractured femur. The fracture site was exposed and 2 mm of the periosteum was cauterized on each side of the fracture. Fracture healing was evaluated with serial radiographs every two weeks. Animals were maintained for intervals of two, four, six or eight weeks after surgery. Specimens from each time interval were subjected to biomechanical and histological evaluation. None of the cauterized fractures healed throughout the eight weeks experimental duration. The radiographical appearance of nonunion models was atrophic. This investigation showed pronounced differences between the experimental nonunions and standard closed fractures both histologically and biomechanically. In conclusion, we have developed a reproducible atrophic nonunion model in the rat femur that simulates the clinical condition in which there is periosteal disruption but no bone defect.

Laser doppler flow imaging of open lower leg fractures in an animal experimental model

PURPOSE

Open lower leg fractures are frequently associated with severe soft tissue damage, followed by osteomyelitis. Using an animal experimental model, we investigated the effect of timing of coverage of a tibial fracture with a local muscle flap.

METHODS

80 rabbits had a tibial fracture induced in a standardised fashion, which was stabilised by screw osteosynthesis. After 3 (group A; n=40) and 7 days (group B; n=40), respectively, the tissue defect was covered by a local gastrocnemius flap. In increasing intervals from 1 to 2, 4, 8, and 16 weeks, the rabbits from each group were killed and the bone fracture was analysed histomorphologically. Cortical microcirculation was measured by 2-channel laser doppler flowmetry.

RESULTS

Muscle flaps after 3 days improved perfusion significantly as compared with 7 days (24 Flux [standard error, 5 Flux] versus 10 Flux [3 Flux]; baseline, 1.4 Flux). Group A animals also displayed a lower rate of necrosis (0 versus 38). The incidence of osteomyelitis was higher in group B than in group A (24% versus 0%).

CONCLUSION

Laser doppler flowmetry was proven to be a reliable, minimally invasive means for identifying avital tissue, leading to reduction in the loss of vital bone tissue in experimental settings.

The role of laser Doppler flowmetry in assessing the viability of bone fragments in an open fracture

The management of open fractures requires excision of all devitalised tissues, both bony and soft tissue, and failure to do so is likely to increase the risk of infection. This study evaluated the applicability of laser Doppler flowmetry for the objective evaluation of fracture fragment viability in an experimental open ballistic fracture over a period of 12 h. The results indicate that this technique could not be used to distinguish between vascularised and non-vascularised fragments at any time, and did not aid the surgeon in their decision making at the time of wound excision. Subjective evaluation, based upon the degree of soft tissue attachment of fragments, was a far better indicator of fragment vascularity, although it had a relatively low specificity. There remains the need for education and training for trauma surgeons in the evaluation of fragment viability to ensure adequate wound excision as part of fracture management.

The effect of surgical dissections on blood flow to the tibial tubercle

Tibial tubercle transfer is often used for the treatment of patella maltracking. Because the periosteum of both sides of the tibia is stripped off along the tibial tubercle and then the bilateral cortices are transferred, this procedure may disturb the blood supply to the tibial tubercle. However, the blood supply to the tibial tubercle has not yet been clearly elucidated. The purpose of this study is to investigate the effect of surgical dissection on blood flow to the tibial tubercle in an animal model using a hydrogen washout technique. Eleven knees of nine mongrel dogs weighing from 7.0 to 19.1 kg were utilized. The blood flow was measured using a hydrogen washout technique. Before performing the surgical procedures, the control blood flow rate of the tibial tubercle averaged 19.6 ml/min per 100 g of tissue. The blood flow rate did not significantly decrease after transecting the periosteum on the lateral side of the tibia alone (P > 0.05). After completing the tibial tubercle osteotomy, the blood flow rate averaged 11.5 ml/min per 100 g of tissue, which is a 25.3% decrease as compared with the value after transecting the periosteum on the lateral side of the tibia alone (P < 0.05). The blood flow rate significantly decreased to 3.4 ml/min per 100 g of tissue after the distal periosteal transection and osteotomy of the distal cortex of the tibial tubercle (P < 0.05). The addition of a medial periosteal transection caused a complete arrest of the blood flow in 10 out of 11 knees, or a 91.2% decrease as compared with the value after a distal periosteal transection and osteotomy of the distal cortex of the tibial tubercle (P < 0.05).

Influence of plate design on cortical bone perfusion and fracture healing in canine segmental tibial fractures

OBJECTIVE

To investigate whether or not the limited contact design of the low-contact dynamic compression plate (LCDCP) provides advantages over the dynamic compression plate (DCP) in the context of cortical bone blood flow, biomechanical properties, and remodeling of bone in segmental tibial fractures.

DESIGN

Randomized trial using canines.

SETTING

Animal research laboratory.

PARTICIPANTS

Eleven canines.

INTERVENTION

Segmental tibial fractures were surgically created in canine tibiae. The tibiae were reduced and stabilized with 316L stainless-steel, 3.5-millimeter, ten-hole plates: LCDCP (n = 5) or DCP (n = 6).

MAIN OUTCOME MEASUREMENTS

Laser Doppler flowmetry evaluated cortical bone perfusion in the proximal tibia, segmental piece, and distal tibia (a) before fracture, (b) after fracture, (c) immediately after plating, and (d) at ten weeks. After the dogs were killed at ten weeks, bending stiffness and load to failure of the tibiae were assessed. Tibial cortical bone porosity and new bone formation were measured.

RESULTS

Cortical bone blood flow was similar between the LCDCP and DCP groups throughout the study. Bending stiffness and load to failure of the tibiae were similar between the two groups. Whereas cortical bone porosity and new bone formation were higher in all plated tibiae at ten weeks compared with controls, no differences in cortical bone porosity were seen between the LCDCP and DCP groups. There was a trend toward significantly more new bone formation in the LCDCP group.

CONCLUSION

The LCDCP is not advantageous in fracture healing or restoration of cortical bone perfusion to devascularized cortex in segmental fractures when plate fixation has been chosen for fracture stabilization. The overall injury following segmental devascularization seems more important to outcome than the type of implant used for fracture fixation up to ten weeks.