Early detection of cerebral glucose uptake changes in the 5XFAD mouse

Brain glucose hypometabolism has been observed in Alzheimer’s disease (AD) patients, and is detected with ¹⁸F radiolabelled glucose, using positron emission tomography. A pathological hallmark of AD is deposition of brain β-amyloid plaques that may influence cerebral glucose metabolism. The five times familial AD (5XFAD) mouse is a model of brain amyloidosis exhibiting AD-like phenotypes. This study examines brain β-amyloid plaque deposition and ¹⁸FDG uptake, to search for an early biomarker distinguishing 5XFAD from wild-type mice. Thus, brain ¹⁸FDG uptake and plaque deposition was studied in these mice at age 2, 5 and 13 months. The 5XFAD mice demonstrated significantly reduced brain ¹⁸FDG uptake at 13 months relative to wild-type controls but not in younger mice, despite substantial β-amyloid plaque deposition. However, by comparing the ratio of uptake values for glucose in different regions in the same brain, 5XFAD mice could be distinguished from controls at age 2 months. This method of measuring altered glucose metabolism may represent an early biomarker for the progression of amyloid deposition in the brain. We conclude that brain ¹⁸FDG uptake can be a sensitive biomarker for early detection of abnormal metabolism in the 5XFAD mouse when alternative relative uptake values are utilized.

Validity of health status measures in patients with ulnar wrist disorders

PURPOSE

To assess measurement properties and construct validity of health status measures.

METHOD

Forty-three patients with surgically managed ulnocarpal impingement completed a self-report mail survey, including regional (Disabilities of the Arm, Shoulder and Hand [DASH] questionnaire), disease-specific (Brigham Functional Scale), and generic (Short Form 36 [SF-36] Acute Health Survey) health status measures and questions on condition severity and work status.

STATISTICAL ANALYSIS

Scores were transformed and frequency distributions constructed to compare the distribution of responses to the measures. Correlation analysis and analysis of variance were applied to assess construct validity.

RESULTS

The DASH and Brigham questionnaires had similar distributions of scores, with a slightly greater spread of responses and no ceiling effect on the DASH. Patients appeared slightly less healthy on the basis of the SF-36 scores, which reflected in part the effect of comorbidities. Both the DASH and the Brigham discriminated across levels of severity and work status; the DASH also discriminated on the basis of type of surgery. The SF-36 was able to discriminate some constructs but not as well as the regional and disease-specific measures.

CONCLUSION

This study provides evidence of construct validity for the DASH and Brigham questionnaires in patients with ulnar wrist problems in the late post-operative period.

Health status following recessional ulnar osteotomy

This study describes the health status of 31 patients who underwent recessional ulnar osteotomy for ulnocarpal impingement. An additional lunotriquetral fusion was performed in 11/31 patients for joint degeneration. Outcomes included the DASH (Disability of arm, shoulder and hand) questionnaire, SF-36 Acute Health Survey, complications, and satisfaction with surgical outcome. Patients were stratified into two groups for analysis: osteotomy alone and osteotomy + fusion. The overall results indicated that osteotomy plus fusion in patients with more advanced ulnocarpal impingement did not equalise patients' post-operative health status to that reported by patients requiring osteotomy alone. Mean DASH and SF-36 physical component scores indicated better health status in the osteotomy group compared with the osteotomy + fusion group after surgery. Forty-one point nine per cent of patients required plate removal, and scar pain persisted in 58%. One patient in each group developed a non-union requiring revision surgery. Patients in both groups were generally satisfied with their surgical result, with a higher proportion of very or completely satisfied patients in the osteotomy group (65%) compared to the osteotomy + fusion group (27%). Overall, recessional ulnar osteotomy appears to be a successful procedure for the treatment of ulnocarpal impingement.

An ultrastructural study of the intimal hyperplasia in healing microarterial anastomoses

The purpose of the study was to investigate the ultrastructure of intimal hyperplastic cells. End-to-end microarterial anastomoses were studied in a rabbit free-tissue-transfer model. There were five experimental groups, with 1, 3, 7, 14, or 28 days follow-up. At sacrifice the anastomoses were tested for patency and then examined by light and electron microscopy. At days 1 and 3 the repaired intima was covered with macrophages and extravasated erythrocytes. At day 7 spindle-shaped fibroblasts with copious rough endoplasmic reticulum were seen. Some of these cells also contained pinocytotic vesicles, filaments with focal densities, and subplasmalemmal attachment sites, the features of smooth muscle cells. At day 14, more cells contained smooth muscle features and these features were also more pronounced. These young myofibroblasts were plumper than adjacent fibroblasts. At day 28 mature myofibroblasts with a full complement of organelles were present. The results, therefore, supported the hypothesis that myofibroblasts are present in the intimal hyperplasia of healing microarterial anastomoses.

Epiphyseal plate transplantation between sites of different growth potential

The purpose was to study epiphyseal plate growth after microvascular transplantation to sites of different growth potential. The hypothesis was that the growth potential of an epiphyseal plate transplant is a function of the donor irrespective of the recipient site to which it is transplanted. Immature rabbits were used in an experiment that transplanted microsurgically revascularized second metatarsal epiphyseal plates. There were three experimental groups in which transplants were made to (i) sites of the same growth potential (orthotopic), (ii) sites of higher growth potential (proximal tibia), and (iii) sites of lower growth potential (third metacarpal). Control groups were nonoperated animals, animals with an anteromedial proximal tibial osteotomy, and nonoperated contralateral limbs of all experimental animals. Postoperative graft viability was checked with fluorochrome labeling. Postoperative growth was measured from serial standardized radiographs. Follow-up was for either 5 or 8 weeks. Animals were then killed, and epiphyseal plate specimens removed for histomorphometric analysis. Results showed that the total growth of experimental second metatarsal transplants was not statistically different (p > 0.05) in any recipient site. It was noted, however, that transplanted epiphyseal plates in all experimental groups grew at lower rates than nonoperated controls.

In vivo measurements of multi-component T2 relaxation behaviour in guinea pig brain

Multi-echo Carr-Purcell-Meiboom-Gill (CPMG) imaging sequences were implemented on 1.5 T and 4.0 T imaging systems to test their ability to measure in vivo multi-component T2 relaxation behavior in normal guinea pig brain. The known dependence of accurate T2 measurements on the signal-to-noise ratio (SNR) was explored in vivo by comparing T2 decay data obtained using three methods to increase SNR (improved RF coil design, signal averaging and increased magnetic field strength). Good agreement between T2 values of nickel-doped agarose phantoms was found between imaging and spectroscopic methods. T2 values were determined for gray matter (GM) and white matter (WM) locations from images of guinea pig brain in vivo. T2 measurements of GM were found to be monoexponential at both field strengths. The mean T2 times for GM were 71 ms at 1.5 T, and 53 ms at 4.0T. The highest average SNR was achieved using an improved RF coil at 4.0T. In this case, two peaks were extracted in WM, a "short" T2 peak at approximately 6 ms, and a "medium" T2 peak at approximately 48 ms. T2 values in GM and the major component of WM were significantly decreased at 4.0T compared to 1.5 T. The improved SNR attained with this optimized imaging protocol at 4.0T has allowed for the first time extraction of the myelin-sensitive T2 component of WM in animal brain in vivo.

Transplantation of epiphyseal plate allografts between animals of different ages

The purpose of the experiment was to study growth of epiphyseal plate allografts after transplantation into subjects of a different age, thus preparing for future transplantation of epiphyseal plate or extremity allografts in children. Microvascular transplantation of proximal tibial epiphyseal plate allografts was performed in skeletally immature New Zealand White female rabbits. The growth of 9-week-old epiphyseal plate allografts was examined in both 9-week-old and 17-week-old recipients, as was the growth of 17-week-old epiphyseal plate allografts in 17-week-old recipients. Immunosuppression was with cyclosporine (Cyclosporine A). Successful transplants were confirmed with 99mTc-MDP isotope scanning, and growth was evaluated with weekly standardized radiographs until death. Growth rate was found to depend on the age of the donor epiphyseal plate and was independent of the age of the recipient. This has clinical implications for the procurement of donor tissue in potential transplantation of epiphyseal plate allografts in children.

Unsatisfactory outcome after lower limb salvage: decision-making pitfalls

We examined unsatisfactory outcome after microvascular reconstruction of 34 injured lower extremities at the Toronto Hospital between 1987 and 1992. Our purpose was to examine those factors that contributed to poor outcome in order to improve decislon making when treating the traumatized lower extremity. For the purpose of this review, poor outcome was defined by either secondary elective amputation or patient dissatisfaction. Patients were divided according to preoperative problem into one of three groups: osteo/cutaneous deficit (group 1), septic nonunion (group 2), and osteomyelitis (group 3). Despite successful microvascular reconstruction in each case, unsatisfactory outcome occurred in six (18%) patients. Four had undergone secondary elective amputation, and two were dissatisfied because of residual pain from another musculoskeletal source. Close examination of the factors that contributed to poor outcome in each of these cases has allowed identification of potential pitfalls that may compromise final outcome after limb salvage. On the basis of our observations and an up-to-date review of the relevant literature, we provide basic guidelines as to when and when not to attempt limb salvage.

Limb salvage surgery and adjuvant radiotherapy for soft tissue sarcomas of the forearm and hand

Twenty-five consecutive patients with soft tissue sarcoma of the forearm and hand were assessed for limb-salvage surgery and were entered into a prospective study evaluating oncologic details and functional outcome. Seventeen patients had received incomplete primary excision elsewhere and presented with local recurrence or residual disease. Three had pulmonary metastases at the time of presentation. Twenty-three patients were candidates for limb-salvage surgery and 20 received adjuvant radiotherapy. The mean follow-up period was 37 months. There was local recurrence in three patients who had initially received marginal excision of the primary sarcoma, and three patients died of systemic disease. Limb function was assessed prospectively using both patient-based and clinician-based functional scoring systems and revealed good to excellent results in all but three patients. Eighty-eight percent of those who survived and did not require amputation were able to return to occupational and activities of daily living with no or minimal functional limitation. This study demonstrates that limb-salvage surgery, with adjuvant radiotherapy when necessary, is an effective alternative to amputation in the majority of patients with sarcoma of the forearm and hand. Radiation toxicity is rarely a problem.

Complex injuries of the forearm. Coverage considerations

Complex forearm injuries involve damage to the skin and underlying tissues. The best results are obtained when a multidisciplinary approach is taken to their management. Management of the acute injury should be done in a manner that takes into consideration late reconstructive procedures and best possible final function outcome. This article reviews initial management and options for soft-tissue coverage. Advantages and disadvantages of a wide variety of procedures are discussed and in addition the authors review some of the more controversial areas and give personal preferences.

Differences in perceived shape from shading correlate with activity in early visual areas

The perception of shape from shading depends on the orientation of the shading gradient [1] [2] [3] [4]. Displays composed of elements with vertically oriented shading gradients of opposite polarity produce a strong and stable percept of 'concave' and 'convex' elements. If the shading gradients are rotated 90 degrees , the depth percept is reduced and appears much more ambiguous. Results from psychophysical [1] [2] [3] [4] [5] [6], neuropsychological [7] and computational studies [8] [9] suggest that the perception of shape from shading engages specific mechanisms in early cortical visual areas. In a three-dimensional functional magnetic resonance imaging (fMRI) study at 1.5 Tesla using a three-dimensional, interleaved-echoplanar imaging technique and a surface radio frequency (RF) coil placed under the visual cortex, we investigated the activity in these early visual areas associated with viewing shape from shading displays at two different orientations. We found significantly greater activation in area V1 and neighbouring low-level visual areas of cortex when subjects viewed displays that led to weak and unstable depth percepts than when they viewed displays that led to strong and stable depth percepts.

Microsurgical treatment of septic nonunion of the tibia. Quality of life results

The outcome of microsurgical reconstruction of septic nonunion of the tibia was described. The series consisted of 15 patients, with Cierny Stage IVA or IVB septic nonunion of the tibia, who were treated in the microsurgical practice of a major tertiary care hospital. Patients with a documented end point of either union or amputation were eligible for inclusion. Patients were treated with wound excision followed by soft tissue and skeletal reconstruction. The outcome measures of interest included clinical measures (time to union or amputation, surgical complications, wound status) and health related quality of life measures (Short Form-36, Western Ontario and McMaster Universities Osteoarthritis Index, and patient satisfaction questionnaires). The average followup time was 3 years. There was 1 microvascular complication and no failures. Two of 15 patients (both Cierny IVB) required amputation after reconstruction. The time to union after bone grafting was an average of 6.5 months in May et al Type III legs (n = 12), 3 months in May et al Type IV legs (n = 1), and 16 months in May et al Type V legs (n = 2). Nine patients completed the questionnaires; Short Form-36 scores were below normative values for the same age group. Scores on the activity limitation component of the Western Ontario and McMaster Universities Osteoarthritis Index seem to be comparable with those of individual's scores after total knee replacement surgery. Despite relatively low scores on the questionnaires, most patients were either very or completely satisfied with the outcome of surgery. Patients often reported that satisfaction was related to preservation of the limb.

Lower extremity free flaps: a review

OBJECTIVE

To identify factors related to free-flap coverage of lower extremity fractures that are linked to a negative outcome.

DESIGN

A chart review.

SETTING

A large microsurgical referral centre.

PATIENTS

From 1981 to 1989, the records of all patients who underwent free-tissue transfer to the lower extremity with more than 1 year of follow-up were selected. From this was drawn a subgroup of 49 patients (mean age, 36 years) who had tibial fractures (55% were motor vehicle injuries) and in almost all cases established soft-tissue or bony defects. They formed the study group.

INTERVENTION

Free-flap transfer.

OUTCOME MEASURES

Factors that might be associated with free-flap failure: mechanism of injury, grade of tibial fracture, history of smoking, diabetes, peripheral vascular disease, ischemic heart disease, vascular compromise in the leg preoperatively, recipient artery used, type of anastomosis, and hypertension or hypotension intraoperatively.

RESULTS

Type IIIB tibial fractures were the most frequent (67%) and carried a significantly (p = 0.02) higher risk of free-flap failure than other types of fracture. Patients underwent a mean of four procedures before referral for free-tissue transfer. The mean time from injury to flap coverage was 1006 days. Stable, long-term coverage of the free flaps was achieved in 78% of patients. Wound breakdown was most often caused by recurrent osteomyelitis (65%). Seventy-four percent of the fractures healed. The amputation rate was 10%. Four patients required repeat free-flap transfer for limb salvage.

CONCLUSIONS

Only the grade of tibial fracture could be significantly related to postoperative free-flap failure.

Microvascular anastomoses. A comparative study of fibrinogen adhesive and interrupted suture techniques

A modified sleeve technique was developed for making microsurgical anastomoses using a commercially produced fibrinogen adhesive called Tisseel. A controlled study was then carried out to compare the new fibrinogen adhesive anastomoses with conventional suture anastomoses in a bilateral groin flap model using 50 consecutive rabbits. Statistical analysis of the results indicated that flap survival rate and vascular patency rate were comparable for the two techniques. The fibrinogen adhesive anastomoses took less time to complete and, subjectively, were less difficult technically. The suture anastomoses were more versatile. Histologic studies revealed that the adhesive did not flow through the sleeve into the lumen, and that, although there was a brief inflammatory response associated with healing, this inflammation was very localized and did not involve the inner layers of the vessel wall or lumen. It was concluded that the new technique was a useful addition to techniques already available.

Microvascular transplantation of physeal allografts

We compared growth in vascularised allograft transplants, autografts and in non-operated physes in rabbits immunosuppressed with cyclosporin A and in non-immunosuppressed animals. Molecular haplotyping was undertaken before operation to ensure allogenicity. Postoperative bone scans and fluorochrome labelling were used to confirm physeal vascularity. The animals were killed at three or five weeks. Proximal tibial physeal autografts, with or without cyclosporin A, or allografts with cyclosporin A, grew at similar rates to the physes of non-operated rabbits. All the operated physes grew at rates significantly greater than their contralateral controls. 99mTc-MDP bone scans accurately predicted the viability of the epiphyseal plate. Quantitative histomorphological analysis of the heights of the physeal proliferative and hypertrophic zones showed that successful physeal transplants have a normal appearance, but when unsuccessful have thickened hypertrophic zones compatible with physeal ischaemia. We discuss the significance of these results in relation to the transplantation of physes in children.

Microvascular transplantation of physeal allografts

We compared growth in vascularised allograft transplants, autografts and in non-operated physes in rabbits immunosuppressed with cyclosporin A and in non-immunosuppressed animals. Molecular haplotyping was undertaken before operation to ensure allogenicity. Postoperative bone scans and fluorochrome labelling were used to confirm physeal vascularity. The animals were killed at three or five weeks. Proximal tibial physeal autografts, with or without cyclosporin A, or allografts with cyclosporin A, grew at similar rates to the physes of non-operated rabbits. All the operated physes grew at rates significantly greater than their contralateral controls. 99mTc-MDP bone scans accurately predicted the viability of the epiphyseal plate. Quantitative histomorphological analysis of the heights of the physeal proliferative and hypertrophic zones showed that successful physeal transplants have a normal appearance, but when unsuccessful have thickened hypertrophic zones compatible with physeal ischaemia. We discuss the significance of these results in relation to the transplantation of physes in children.

Restriction fragment-length polymorphism analysis of the major histocompatibility complex in New Zealand white rabbits

As a model system, rabbits are particularly useful in transplantation studies because of their size and accessibility. However, inbred rabbits of known MHC haplotype are not commercially available, and there are few monoclonal antibody reagents available to permit serological typing of experimental animals prior to transplant. Here we present a rapid and reliable method to distinguish rabbits that differ at their MHC class I and class II loci, and present 34 class I and 16 class II haplotypes determined by restriction fragment-length polymorphism analysis of outbred heterozygous rabbits. The applicability of this molecular typing system to transplantation experiments in the New Zealand White rabbit is discussed.

Can quantitative 99mTc-MDP bone scans be used to predict longitudinal growth of epiphyseal plate allografts after microvascular transplantation? An experimental study

Allograft and autograft microvascular proximal tibial epiphyseal plate transplants were performed in female New Zealand White (NZW) rabbits to quantify the growth rate and total growth potential of immunosuppressed and nonimmunosuppressed rabbits. The purpose of this experiment is to examine whether the 99mTc-MDP radionuclide uptake of the transplanted epiphyseal plate at 1 week postoperatively, done to assess anastomotic patency of the transplant, could also serve as a predictor of eventual longitudinal growth of the transplant or replant. All transplants and replants demonstrating positive 99mTc-MDP uptake in the proximal tibial epiphyseal plate at 1 week showed continued longitudinal growth. The precise amount of 99mTc-MDP uptake, however, did not correlate with the amount of growth at 3 and 5 weeks follow-up.

Heterotopic microvascular epiphyseal plate transplantation: a new model using the rabbit metatarsal

The purpose of this study is to develop a new vascularized epiphyseal plate model in the New Zealand White rabbit using a metatarsal epiphyseal plate having limited longitudinal growth potential. Such a model could be utilized in various experiments aimed at manipulating epiphyseal plate growth. The viability of the harvested live subject grafts was demonstrated with continued epiphyseal uptake during Tc99-MDP radionuclide bone scanning. The currently described models used in epiphyseal transplant research all involve long bone epiphyseal plates with significantly greater growth potential than the new metatarsal model. This new model therefore fills a void in the field by allowing investigators to transplant a growth plate with limited growth potential into any heterotopic site and study the effects of various hormonal and physical influences upon epiphyseal plate growth performance.

Epiphyseal plate transplantation: an historical review

Non-vascularized and vascularized transplantation of epiphyseal plate autografts have been performed both clinically and experimentally for over 100 years. However, the ultimate clinical goal of vascularized transplantation of epiphyseal plate allografts for paediatric extremity reconstruction remains elusive, due primarily to the lack of suitably nontoxic techniques to prevent graft rejection. We have summarized the published clinical and experimental investigations of vascularized epiphyseal plate transplantation, and organized the experiments and clinical operations into four main groups: (1) local vascular studies on unmanipulated epiphyseal plates, (2) studies of epiphyseal plate behaviour after orthotopic replantation, (3) studies of epiphyseal plate behaviour after heterotopic transplantation, and (4) studies of epiphyseal plate behaviour after allograft transplantation. Prior investigations into the non-vascularized transplantation of epiphyseal plate autografts and allografts are presented as background. These groups of studies serve as the building blocks for the more clinically applicable experimental investigations outlined in the final section of this review.

Outcome of carpal tunnel release in diabetic patients

A retrospective study of 15 diabetic patients (20 hands), who underwent carpal tunnel release, was performed to determine the outcome. All patients had a minimum of 18 months of follow-up. Outcome was considered excellent if there was complete resolution of symptoms and this occurred in 35% of the treated hands. Eight hands (40%) had a good outcome with significant improvement of pre-operative symptoms. Outcome was considered poor when symptoms were minimally improved, unchanged, or worse after surgery and this occurred in 25% of treated hands. All hands with a poor final result had either no electrodiagnostic evidence of localized compression or only mild compression in pre-operative nerve conduction studies. It was postulated that the contribution of localized compression to pre-operative hand symptoms was less than the contribution of peripheral neuropathy in these hands.

Extremity arteriovenous malformations: review of a series

OBJECTIVE

To examine the diagnosis and treatment of arteriovenous malformations in adults, because of the tendency of the condition to recur.

DESIGN

Chart and literature review.

SETTING

Three tertiary-care hospitals.

PATIENTS

Twelve adults with diffuse arteriovenous malformations of the extremities.

INTERVENTIONS

Surgery of embolotherapy.

MAIN OUTCOME MEASURE

Recurrence.

RESULTS

Of the 12 cases reviewed, the arteriovenous malformations recurred in 8 patients; 2 of these were well, 6 months and 2 years after a second or third treatment. Two others were well, 2 months and 5 years after surgery or embolotherapy. One pregnant woman, whose case is described in detail, received no treatment, and her arteriovenous malformation diminished in size after her child was born. The outcome in the last patient is unknown.

CONCLUSION

Diffuse arteriovenous malformations recur after ablative treatment.

Pregnancy-induced carpal tunnel syndrome requiring surgical release longer than 2 years after delivery

OBJECTIVE

To determine the percentage of patients in whom carpal tunnel syndrome was induced by pregnancy, the presence of any risk factors causing persistent symptoms after delivery, and the outcome of surgical decompression in these patients.

METHODS

We reviewed retrospectively the records of 100 consecutive women treated by carpal tunnel release in our unit from 1988-1991.

RESULTS

Seven patients had the onset of hand symptoms during pregnancy. One patient was diabetic and worked as a machine operator, but none of the others had predisposing factors that could have led to persistent postpartum symptoms. The hand symptoms persisting after delivery initially required conservative treatment only. However, 2-16 years later, symptoms became severe enough to warrant surgical release of the carpal tunnel. All patients had resolution of symptoms after surgery.

CONCLUSION

Some patients with mild residual hand symptoms due to carpal tunnel syndrome may initially respond to conservative treatment, but 2-16 years later, symptoms may become severe enough to warrant surgical release. We recommend long-term follow-up of patients with residual postpartum hand symptoms.

Donor site deficit of the osteocutaneous radial forearm flap

A functional evaluation was made of osteocutaneous radial forearm flap donor upper extremities at a mean 19.4 months postoperatively. Donor deficits were evaluated as follows: (1) skin: subjective appearance and durability; (2) skeleton: range of motion of adjacent joints; (3) vessels: cold intolerance, digital temperature, digital--brachial index; (4) muscle: key pinch; (5) nerve: two-point discrimination of dorsal first web space. Ten consecutive patients with a mean donor site area of 51.5 cm2 and mean length of harvested radius of 10.9 cm were studied. Incomplete skin graft take at the donor site (7 of 10 patients) and appearance of fair or poor (6 of 10 patients) were frequent cutaneous complications. Wrist range of motion was decreased with pronation (90%), flexion (90%), and extension (89%). Mean digital temperature, comparing extremities that did (operated) and did not (nonoperated) undergo surgery, or comparing the radial artery-supplied fingers to the ulnar artery-supplied fingers within the same operated hand showed no effect from the lost radial artery. Mean digital-brachial index was 1.24 for the nonoperated and 1.15 for the operated extremity. Key pinch on the operated side was a mean of 74% of the nonoperated side. Although raising the flap creates multiple tissue deficits, each with the potential to alter upper extremity function, detailed functional evaluation failed to demonstrate significant alteration in upper extremity function after flap harvest.

Bernard O'Brien: the microsurgical transfer of immature bone

Bernard O'Brien was one of the pioneers of vascularized epiphyseal plate transfer. His clear understanding of the wide array of potential applications for reconstructive microsurgery stimulated his interest in the transfer of growing long bones. Investigations have been carried out in his laboratory since the earliest days of skeletal free tissue transfers. This paper describes the work done with epiphyseal plate transfers in O'Brien's laboratory. Research from other centers is then reviewed. Finally, the experience with clinical application is described.

Short-term response of epiphyseal plate cell populations following selective devascularization and microsurgical revascularization

The distal femoral epiphyseal plates of 21 8-week-old New Zealand white rabbits were totally or partially (nutrient artery only) devascularized, or devascularized and then microsurgically revascularized. Sacrifice was at 24, 48 or 72 hours postoperatively. The heights of the proliferative and hypertrophic zones of the epiphyseal plates operated upon were compared with the contralateral control epiphyseal plates for both the central and the peripheral regions of the epiphyseal plate. Neither extent of devascularization nor revascularization had a significant effect on the height of the proliferative zone of chondrocytes at any of the follow-up intervals. Selective devascularization of the nutrient artery led to a significant increase in height of the central region of the hypertrophic zone of chondrocytes at 48 and 72 hours. Microsurgical revascularization did not lead to a significant change in the height of either the central or the peripheral regions of the hypertrophic zone of chondrocytes at any of the follow-up intervals. This study is another 'building block' experiment toward vascularized epiphyseal plate transplantation in humans.

Microsurgical free flap transfer in sickle cell disease

A patient with sickle cell anemia and recurrent ankle ulceration is presented. Multiple previous skin grafts did not resolve the painful ulcers. A radial forearm free flap was attempted. Despite preoperative transfusions to reduce her hemoglobin S levels, postoperative thrombosis occurred. The true risk of free flap failure in sickle cell anemia is unknown and there is still debate about the exact nature of the hypercoagulable state that exists in this disease. We recommend, however, that consideration is given to the use of prophylactic anticoagulation in patients undergoing complex procedures or in whom other risk factors have been identified.

Skeletal fixation in the rabbit knee transplantation model

The immature rabbit knee model for epiphyseal plate transplantations has been used by a number of investigators. Rigid fixation of the femoral osteosynthesis has been difficult to achieve reliably. This paper describes a new technique for obtaining consistent and satisfactory skeletal fixation in this model. The tibia was internally fixed with an ASIF/AO four-hole minifragment plate. The femur was fixed with a 2.4 mm Steinman pin supplemented with two 26 gauge stainless steel interosseous wire loops placed at right angles to each other.

Axial pattern skin flaps in cats

The major direct cutaneous vessels identified in the cat include the omocervical, thoracodorsal, deep circumflex iliac, and caudal superficial epigastric arteries. Axial pattern skin flaps based on the thoracodorsal and caudal superficial epigastric arteries have been developed in cats. Rotation of these flaps as islands allows skin coverage to the carpus and metatarsus, respectively. The thoracodorsal and caudal superficial epigastric flaps provide a practical, one-step option in the reconstruction of large skin defects involving the distal extremities of cats.

Experimental cutaneous free flap transfers in the horse

Equine limb wounds often heal slowly by epithelialization, and large scars are a frequent end result. In some ways, they resemble the wound associated with human tibial injuries. The literature indicates that previous investigators have failed to transfer free skin flaps successfully in the horse. In this paper, we review our experimental work with the deep circumflex iliac flap in the horse. Dissections of 20 cadavers confirmed the anatomical consistency of the flap. Four flaps survived well when elevated as island flaps, but five orthotopic and nine heterotopic free flap transfers all failed. The cause of failure is still unknown, but our experiments suggested that the horse must be highly susceptible to ischemic reperfusion injury.

Free tissue transfer of digital food pads for reconstruction of the distal limb in the dog

Reconstructive procedures used in salvaging distal limb injuries in the dog are reviewed. Techniques employed to resurface the distal weight-bearing surface include local reconstruction using pedicle flap transposition of foot pads. The development of a previously described free microneurovascular digital foot pad flap is reviewed; the experimental results and potential for clinical use of the free flap are discussed.

Experimental and clinical free cutaneous transfers in the dog

Various reconstructive techniques have been applied to the management of difficult wounds in the dog. Wounds in the distal extremities and on the face are hard to manage by conventional methods. A free cutaneous flap, based on the superficial cervical vessels, was developed and used in a series of experimental and clinical cases. Six of eight experimental orthotopic transfers survived. The two failures were thought to be related to technical error. The seven flaps, used in clinical cases, all survived and successfully resolved the dogs' clinical problems.

Microsurgical free bone transfer in the dog

Bone grafts have been used extensively for the reconstruction of skeletal injury in dogs. Cancellous and corticocancellous chip autografts are used for their osteoinductive and osteoconductive properties. Fresh, fresh-frozen, freeze-dried, and ethylene oxide-sterilized cortical allografts have been recommended for the reconstruction of segmental cortical defects. Donor sites for microsurgical bone transfer have been identified experimentally in the dog, but these remain to be used clinically. This paper reviews the anatomy and structural characteristics of donor sites for microsurgical bone transfer. Potential clinical indications for microsurgical bone transfer in the dog are described.

Rotating shaft avulsion amputations of the thumb

In a three-year period twenty-nine patients were treated for rotating shaft avulsion amputations of the thumb. Twenty-three thumbs were considered suitable for replantation. A staged approach, consisting of primary replantation and secondary nerve grafting and tendon reconstruction, was used because of concern that survival rates would be low. Survival was achieved in nineteen of twenty-three replantations. At mean follow-up of 20.5 months grip strength was 94.6% of the unaffected side and key pinch was 77.1%. Five patients achieved a two-point discrimination less than five millimeters. Success was better anticipated and now a full reconstruction is carried out in a single-stage procedure.

Identification of a free skin flap from the region vascularized by the deep circumflex iliac artery of horses

Areas of skin vascularized by large axial vessels potentially suitable for microvascular anastomosis were investigated in 10 horse cadavers. Eleven such areas were dissected, and the skin over the flank region vascularized by the deep circumflex iliac artery was most suitable. The anatomy of this area was further defined, using angiography and latex injection studies on 10 cadavers.

Microneurovascular free digital pad transfer in the dog

By cadaver dissections, the fifth digit of the canine hind limb was determined to have a consistent neurovascular anatomy, and therefore be a suitable donor for an axial pattern digital pad flap. The defined digital pad flap was transferred to the region of an excised metacarpal pad by microneurovascular anastomoses in five operations on four dogs. One flap failure was considered to result from failure of the venous anastomosis. In all four successful transfers, cutaneous sensation was reestablished on average in 78 days. There was histologic evidence of nerve regeneration across the anastomosis in one dog at week 24. The transferred pads of three dogs monitored for 15 months underwent hypertrophic changes. There were no complications in two active dogs. In one dog, superficial ulceration of a region of the flap adjacent to the pad required surgical revision. This dog continued to show mild lameness after daily runs of 3 to 4 km.

Thoracodorsal and caudal superficial epigastric axial pattern skin flaps in cats

Nonselective angiography, selective angiography, and gross dissection of 15 cadavers were performed to delineate direct cutaneous arteries in the cat. The omocervical, deep circumflex iliac, thoracodorsal, and caudal superficial epigastric arteries were identified by nonselective angiography. Selective angiography and gross dissection allowed assessment of the origin and vascular territories of the thoracodorsal and caudal superficial epigastric arteries. Orthotopic and heterotopic transfers of thoracodorsal and caudal superficial epigastric island flaps were performed on eight cats. All flaps were successful although areas of necrosis at the caudodistal tips were evident in most of the thoracodorsal flaps. The rotated thoracodorsal flaps extended to the carpi. Caudal superficial epigastric flaps enabled coverage to the metatarsus. Seroma formation and partial dehiscence were minor complications.

Transfer of deep circumflex iliac flaps to the tarsus by microvascular anastomosis in the horse

Eighteen deep circumflex iliac flaps were elevated in healthy adult horses. Four flaps survived well when elevated as islands, but five orthotopic flaps and nine heterotopic flaps transferred to the tarsus and face failed. Technical reasons could explain the failure of the orthotopic flaps, but not the heterotopic flaps. Failure of the heterotopic flaps was apparently caused by the no-reflow phenomenon.

Attritional flexor tendon ruptures by an old lunate dislocation

A 76-year-old man sustained attritional disruption of the extrinsic flexor tendons to the ulnar two fingers over 40 years after an untreated palmar lunate dislocation. Spontaneous flexor tendon rupture is rare without wrist joint pathology, even in the absence of chronic pain or median nerve compression.

Experimental microvascular growth plate transfers. Part 2--Investigation of feasibility

We investigated the feasibility in the dog of using transfers of the distal ulna into the radius either as growth plate replacements or as accessory growth plates in the diaphysis. Preliminary work determined the most satisfactory method of skeletal fixation. The experimental study showed that transfers used as growth plate replacements grew at almost normal rates, uniting with the recipient bone in a mean of 7.1 weeks. Transfers into the diaphysis initially nearly doubled the growth rate of the radius, although in the long-term results were unsatisfactory, because of fracture of the graft after a mean period of 8.2 weeks.

Experimental microvascular growth plate transfers. Part I--Investigation of vascularity

A model was developed in the dog to allow both the metaphysis and epiphysis of the distal ulnar growth plate to be microsurgically revascularised from the pedicle of the anterior interosseous vessels. With both circulations revascularised, grafts retained their structural integrity and growth continued at rates only slightly less than normal (mean 85%). If either or both circulations were not revascularised, growth rates were lower and were associated with skeletal collapse in the ischaemic bone segment.

Osteoid osteomata of the distal phalanx

Osteoid osteomata are rarely found in the distal phalanges of the hand. The 23 cases in the English language literature are discussed and two additional cases are described. The usual presenting features are chronic pain, nail enlargement and increase in size of the terminal part of the digit. Diagnosis is difficult but surgical excision is effective for treating the patients' pain.