The influence of soft tissue trauma on bone regeneration after acute limb shortening

Comparison of treatment indices associated with the correction and lengthening of deformities along various lower limb frontal plane directions

PURPOSE

The Taylor spatial frame (TSF) provides higher precision in the dimensional correction of some lower limb deformities. However, no study to date has compared the osteogenesis outcome of correction and lengthening among various directions in the frontal plane. We examined the relationship between the external fixation index (EFI) and the direction of correction in the frontal plane.

METHODS

We classified 25 patients undergoing correction with the TSF into three groups: Group A (8 patients, varus deformity), Group B (6 patients, valgus deformity), and Group C (9 patients, non-correction in the frontal plane). We excluded patients who underwent chemotherapy, were converted to internal fixation, had infection or pseudarthrosis, and in whom the corrected gain was <2.4 cm.

RESULTS

No significant differences in age, sex, etiology of deformity, complication due to deformity in another plane, osteotomy distribution, TSF use duration, and correction distance were found. The average EFI was 83.4, 60.5, and 51.2 days/cm in Groups A, B, and C, respectively, with the EFI being significantly higher in Group A than in Group C (P < 0.05).

CONCLUSIONS

Osteogenesis of varus deformities was more prolonged than that of non-correction in the frontal plane. These results provide useful insights that can aid in minimizing complications due to external fixation and improving our understanding of the mechanism of osteogenesis in the tibia.

CYR61 improves muscle force recreation in a rabbit trauma model

BACKGROUND

Critically elevated compartment pressures after complicated tibial fractures may result in fibrosis and therefore scarring of muscles with impaired function. Several studies have shown a relationship between angiogenesis and more effective muscle regeneration. Cysteine-rich angiogenic inducer 61 (CYR61) is associated with angiogenesis but it is not clear whether it would restore muscle force, reduce scarring or improve angiogenesis after acute musculoskeletal trauma.

OBJECTIVE

We researched whether local application of CYR61 (1) restores muscle force, (2) reduces scar tissue formation, and (3) improves angiogenesis.

METHODS

We generated acute soft tissue trauma with temporary ischemia and increased compartment pressure in 22 rabbits and shortened the limbs to simulate surgical fracture debridement. In the test group, a CYR61-coated collagen matrix was applied locally around the osteotomy site. After 10 days of limb shortening, gradual distraction of 0.5 mm per 12 hours was performed to restore the original length. Muscle force was measured before trauma and on every fifth day after trauma. Forty days after trauma we euthanized the animals and histologically determined the percentage of connective and muscle tissue. Immunohistology was performed to analyze angiogenesis.

RESULTS

Recovery of preinjury muscle strength was significantly greater in the CYR61 group (2.8 N; 88%) as compared to the control (1.8 N; 53%) with a moderate reduction of connective tissue (9.9% vs. 8.5%). Immunohistochemical staining showed that blood vessel formation increased significantly (trauma vs. control 38.75 ± 27.45 mm2 vs. 24.16 ± 19.81 mm2).

CONCLUSIONS

Local application of CYR61 may improve restoration of muscle force and accelerate muscle force recovery by improving angiogenesis and moderately reducing connective tissue.

VEGF improves skeletal muscle regeneration after acute trauma and reconstruction of the limb in a rabbit model

BACKGROUND

Complicated tibial fractures with severe soft tissue trauma are challenging to treat. Frequently associated acute compartment syndrome can result in scarring of muscles with impaired function. Several studies have shown a relationship between angiogenesis and more effective muscle regeneration. Vascular endothelial growth factor (VEGF) is associated with angiogenesis but it is not clear whether it would restore muscle force, reduce scarring, and aid in muscle regeneration after acute musculoskeletal trauma.

QUESTIONS/PURPOSES

Therefore, we asked whether local application of VEGF (1) restores muscle force, (2) reduces scar tissue formation, and (3) regenerates muscle tissue.

METHODS

We generated acute soft tissue trauma with increased compartment pressure in 22 rabbits and shortened the limbs to simulate fracture débridement. In the test group (n = 11), a VEGF-coated collagen matrix was applied locally around the osteotomy site. After 10 days of limb shortening, gradual distraction of 0.5 mm per 12 hours was performed to restore the original length. Muscle force was measured before trauma and on every fifth day after trauma. Forty days after shortening we euthanized the animals and histologically determined the percentage of connective and muscle tissue.

RESULTS

Recovery of preinjury muscle strength was greater in the VEGF group (2.4 N; 73%) when compared with the control (1.8 N; 53%) with less connective and more muscle tissue in the VEGF group. The recovery of force was related to the percentage of connective tissue versus muscle fibers.

CONCLUSIONS

Local application of VEGF may improve restoration of muscle force by reducing connective tissue and increasing the relative amount of muscle fibers.

CLINICAL RELEVANCE

VEGF may be useful to improve skeletal muscle repair by modulating muscle tissue regeneration and fibrosis reduction after acute trauma.

Cysteine-rich matricellular protein improves callus regenerate in a rabbit trauma model

PURPOSE

Open fractures with severe soft-tissue trauma are predisposed to poor bone healing. The vital coupling between osteo- and angiogenesis is disturbed. Cysteine-rich protein 61 (CYR61) is an angiogenic inducer promoting vascularisation. However, little is known about the effect of CYR61 on the callus regenerate after acute musculoskeletal trauma. Therefore, our aim was to determine whether local administration of CYR61: (1) has an influence on callus formation and remodelling, (2) increases bone volume and (3) partially restores callus stability.

METHODS

A musculoskeletal trauma was created in 20 rabbits. To simulate fracture-site debridement, the limb was shortened. In the test group, a CYR61-coated collagen matrix was locally applied around the osteotomy. After ten days, gradual distraction was commenced (0.5 mm/12 h) to restore the original length. New bone formation was evaluated histomorphometrically, radiographically and biomechanically.

RESULTS

Osseus consolidation occured in all animals. Average maximum callus diameter was higher in the test group [1.39 mm; standard deviation (SD) = 0.078 vs 1.26 mm (SD = 0.14); p = 0.096]. In addition, bone volume was higher (p = 0.11) in the test group, with a mean value of 49.73 % (SD = 13.68) compared with 37.6 % (SD = 5.91). Torsional strength was significantly higher (p = 0.005) in the test group [105.43 % (SD = 31.68 %) vs. 52.57 % (SD = 24.39)]. Instead, stiffness of the newly reconstructed callus decreased (64.21 % (SD = 11.52) vs. 71.30 % (SD = 32.25) (p = 0.81)).

CONCLUSIONS

CYR61 positively influences callus regenerate after acute trauma, not only histologically and radiographically but also biomechanically, most probably by a CYR61-associated pathway.

Knee joint transplantation combined with surgical angiogenesis in rabbits--a new experimental model

PURPOSE

We have previously described a means to maintain bone allotransplant viability, without long-term immune modulation, replacing allogenic bone vasculature with autogenous vessels. A rabbit model for whole knee joint transplantation was developed and tested using the same methodology, initially as an autotransplant.

MATERIALS/METHODS

Knee joints of eight New Zealand White rabbits were elevated on a popliteal vessel pedicle to evaluate limb viability in a nonsurvival study. Ten additional joints were elevated and replaced orthotopically in a fashion identical to allotransplantation, obviating only microsurgical repairs and immunosuppression. A superficial inferior epigastric facial (SIEF) flap and a saphenous arteriovenous (AV) bundle were introduced into the femur and tibia respectively, generating a neoangiogenic bone circulation. In allogenic transplantation, this step maintains viability after cessation of immunosuppression. Sixteen weeks later, X-rays, microangiography, histology, histomorphometry, and biomechanical analysis were performed.

RESULTS

Limb viability was preserved in the initial eight animals. Both soft tissue and bone healing occurred in 10 orthotopic transplants. Surgical angiogenesis from the SIEF flap and AV bundle was always present. Bone and joint viability was maintained, with demonstrable new bone formation. Bone strength was less than the opposite side. Arthrosis and joint contractures were frequent.

CONCLUSION

We have developed a rabbit knee joint model and evaluation methods suitable for subsequent studies of whole joint allotransplantation.

Local application of VEGF compensates callus deficiency after acute soft tissue trauma--results using a limb-shortening distraction procedure in rabbit tibia

Acute soft tissue trauma influences callus formation and fracture healing. Several studies showed a relationship between angiogenesis and bone formation during distraction osteogenesis. The purpose of this study was to investigate the influence of controlled release of vascular endothelial growth factor (VEGF) on callus formation in a limb-shortening distraction procedure after acute compartment syndrome. Acute soft tissue trauma with critical increased compartment pressure was generated in 22 rabbits, and the limb was shortened simulating fracture site debridement. In the test group (n=11), a VEGF-coated collagen matrix was locally applied around the fracture, while no collagen was applied in the control group (n=11). Following 10 days in limb shortening, a gradual distraction of 0.5 mm/12 h was performed using an external fixation device and followed up for 40 days. Osseous consolidation occurred in all animals. Average callus diameter (1.54 ± 0.8 vs. 1.27 ± 0.14 mm) and torsional strength (72% vs. 46% of normal) were significantly higher in the test versus the control group. Blood vessel formation increased with a significantly higher number of vessels (6.3 vs. 3.81/mm2 ) and larger cross-sectional area (>40 µm, 90.5% vs. 86%) in the test versus control group. The results showed that locally applied VEGF stimulates fracture healing after acute soft tissue trauma and might be an option for fracture treatment in cases with severe soft tissue damage.

Shortening and secondary relengthening for chronically infected tibial pseudarthroses with poor soft tissues

BACKGROUND

The treatment of chronically infected tibial pseudarthroses with poor soft tissues ends with amputation on many occasions. Aggressive débridement of bone and soft tissue and reconstruction of the extremity, performed as a limb salvage procedure, is an alternative treatment option to amputation.

METHODS

Our patients had a mean age of 42 years. According to the Paley classification, one of the patients had A2 pseudoarthrosis, four had B2, and three had B3. One had localized infection, whereas the other seven had diffuse infection, according to the Cierny-Mader system. The mean duration of the infection was 10.75 years, and the mean number of previous operations was 5.13. The mean shortness was 2.4 cm, and the mean bone defect was 1 cm.

RESULTS

The mean primary shortening was 8.6 cm, the mean duration of the fixator stay was 9.6 months, and the mean distraction index was 39.1 days/cm. The mean duration of follow-up was 25 months. The bone results were excellent in four cases, good in two, and fair in the other two. The functional results were excellent in one patient, good in six, and fair in one. A total of 11 minor and 3 major complications were seen during the treatment, and one case resulted in amputation.

CONCLUSIONS

Despite the high rate of complications, our treatment method enabled limb salvage for patients who had previously been candidates for amputation. With this treatment, there is less need for a second operation, and an additional operation is not necessary for soft tissue coverage.