Free functional muscle transfer for lower extremity reconstruction

BACKGROUND

Free functional muscle transfer is a reconstructive strategy for the reconstruction of lost muscle units in the lower extremity after oncologic resection, trauma, compartment syndrome, or severe nerve injuries. Under appropriate circumstances, free functional muscle transfer may be the only suitable reconstructive option. This article reviews the underlying principles of free functional muscle transfer, its application to lower extremity reconstruction, appropriate patient selection, and surgical techniques.

METHODS

The underlying principles of free functional muscle transfer, its application to lower extremity reconstruction, appropriate patient selection, and surgical techniques are presented. Commonly used donor muscles appropriate for each type of functional defect are discussed. A review of recent publications on free functional muscle transfer in the lower extremity was also performed.

RESULTS

Good functional recovery with a Medical Research Council grade of up to 4/5 and full range of motion can be attained with free functional muscle transfer. Clinical outcomes and specific parameters for published case series in lower extremity free functional muscle transfer are presented and an illustrative case.

CONCLUSION

Free functional muscle transfer is a suitable treatment for the appropriate patient to restore essential functions and potentially regain ambulation. However, additional published clinical outcomes are needed and represent a major area for further investigation.

A Simple Brochure Improves Disposal of Unused Opioids: An Observational Cross-Sectional Study

BACKGROUND

We evaluated the effectiveness of a simple, low-cost educational brochure in improving disposal rates of unused opioids after outpatient upper extremity surgery.

METHODS

This cross-sectional study enrolled eligible adult patients from a peripheral nerve clinic between November 2017 and September 2018. Patients either received or did not receive the educational brochure, which outlined a simple method to dispose of unused opioids and completed a survey at 2 weeks after surgery. We compared the proportion of patients who disposed of unused opioids after surgery between the group that had received the brochure and the group that had not. Categorical data were analyzed with χ² test, proportions data with binomial tests, and numerical data with Mann-Whitney U test, all with a significance level of P < .05.

RESULTS

There were 339 survey respondents. Nineteen patients who did not meet inclusion criteria were excluded. Of the 320 remaining patients, 139 received the brochure and 181 did not. An additional 55 patients were excluded due to preoperative opioid use. Overall, 35.3% of recipients and 38.3% of those who did not receive the brochure used all of their prescribed opioid medication (P = .625; confidence interval = -14.6%-8.8%). Among patients with unused opioid medication, a significantly higher proportion of brochure recipients disposed of the medicine compared with those who did not receive the brochure (46.7% vs 19.6%, P < .001).

CONCLUSIONS

Distribution of an educational brochure significantly improved disposal of unused opioids after surgery. This easily implemented intervention can improve disposal of unused opioids and ultimately decrease excess opioids available for diverted use in the community.

Nerve transfers for femoral nerve palsy: an updated approach and surgical technique

OBJECTIVE

Femoral nerve palsy results in significant impairment of lower extremity function due to the loss of quadriceps muscle function. The authors have previously described their techniques utilizing the anterior obturator and sartorius nerves for transfer in cases of femoral nerve palsy presenting within 1 year of injury. In the current study, the authors discuss their updated techniques, results, and approach to partial and complete femoral nerve palsies using femoral nerve decompression and nerve transfers.

METHODS

They conducted a retrospective review of patients with femoral nerve palsies treated with their technique at the Washington University School of Medicine in 2008-2019. Primary outcomes were active knee extension Medical Research Council (MRC) grades and visual analog scale (VAS) pain scores.

RESULTS

Fourteen patients with femoral nerve palsy were treated with femoral nerve decompression and nerve transfer: 4 with end-to-end (ETE) nerve transfers, 6 with supercharged end-to-side (SETS) transfers, and 4 with ETE and SETS transfers, using the anterior branch of the obturator nerve, the sartorius branches, or a combination of both. The median preoperative knee extension MRC grade was 2 (range 0-3). The average preoperative VAS pain score was 5.2 (range 1-9). Postoperatively, all patients attained an MRC grade 4 or greater and subjectively noted improved strength and muscle bulk and more natural gait. The average postoperative pain score was 2.3 (range 0-6), a statistically significant improvement (p = 0.001).

CONCLUSIONS

Until recently, few treatments were available for high femoral nerve palsy. A treatment strategy involving femoral nerve decompression and nerve transfers allows for meaningful functional recovery and pain relief in cases of partial and total femoral nerve palsy. An algorithm for the management of partial and complete femoral nerve palsies and a detailed description of surgical techniques are presented.

Femoral nerve decompression and sartorius-to-quadriceps nerve transfers for partial femoral nerve injury: a cadaveric study and early case series

OBJECTIVE

Partial femoral nerve injuries cause significant disability with ambulation. Due to their more proximal and superficial location, sartorius branches are often spared in femoral nerve injuries. In this article, the authors report the benefits of femoral nerve decompression, demonstrate the feasibility of sartorius-to-quadriceps nerve transfers in a cadaveric study, describe the surgical technique, and report clinical results.

METHODS

Four fresh-frozen cadaveric lower limbs were dissected for anatomical analysis of the sartorius nerve. In addition, a retrospective review of patients with partial femoral nerve injuries treated with femoral nerve decompression and sartorius-to-quadriceps nerve transfers was conducted. Pre- and postoperative knee extension Medical Research Council (MRC) grades and pain scores (visual analog scale) were collected.

RESULTS

Up to 6 superficial femoral branches innervate the sartorius muscle just distal to the inguinal ligament. Each branch yielded an average of 672 nerve fibers (range 99-1850). Six patients underwent femoral nerve decompression and sartorius-to-quadriceps nerve transfers. Four patients also had concomitant obturator-to-quadriceps nerve transfers. At final follow-up (average 13.4 months), all patients achieved MRC grade 4-/5 or greater knee extension. The average preoperative pain score was 5.2, which decreased to 2.2 postoperatively (p = 0.03).

CONCLUSIONS

Femoral nerve decompression and nerve transfer using sartorius branches are a viable tool for restoring function in partial femoral nerve injuries. Sartorius branches serve as ideal donors in quadriceps nerve transfers because they are expendable, are close to their recipients, and have an adequate supply of nerve fibers.

Femoral nerve transfers for restoring tibial nerve function: an anatomical study and clinical correlation: a report of 2 cases

Sciatic nerve injuries cause debilitating functional impairment, particularly when the injury mechanism and level preclude reconstruction with primary grafting. The purpose of this study was to demonstrate the anatomical feasibility of nerve transfers from the distal femoral nerve terminal branches to the tibial nerve and to detail the successful restoration of tibial function using the described nerve transfers.

Six cadaveric legs were dissected for anatomical analysis and the development of tension-free nerve transfers from femoral nerve branches to the tibial nerve. In 2 patients with complete tibial and common peroneal nerve palsies following sciatic nerve injury, terminal branches of the femoral nerve supplying the vastus medialis and vastus lateralis muscles were transferred to the medial and lateral gastrocnemius branches of the tibial nerve. Distal sensory transfer of the saphenous nerve to the sural nerve was also performed. Patients were followed up for lower-extremity motor and sensory recovery up to 18 months postoperatively.

Consistent branching patterns and anatomical landmarks were present in all dissection specimens, allowing for reliable identification, neurolysis, and coaptation of donor femoral and saphenous nerve branches to the recipients. Clinically, the patients obtained Medical Research Council Grade 3 and 3+ plantar flexion by 18 months postoperatively. Improved strength was accompanied by improved ambulation in both patients and by a return to competitive sports in 1 patient. Sensory recovery was demonstrated by an advancing Tinel sign in both patients.

This study illustrates the clinical success and anatomical feasibility of femoral nerve to tibial nerve transfers after proximal sciatic nerve injury.

Rectus Abdominis Motor Nerves as Donor Option for Free Functional Muscle Transfer: A Cadaver Study and Case Series

BACKGROUND

Current management of brachial plexus injuries includes nerve grafts and nerve transfers. However, in cases of late presentation or pan plexus injuries, free functional muscle transfers are an option to restore function. The purpose of our study was to describe and evaluate the rectus abdominis motor nerves histomorphologically and functionally as a donor nerve option for free functional muscle transfer for the reconstruction of brachial plexus injuries.

METHODS

High intercostal, rectus abdominis, thoracodorsal, and medial pectoral nerves were harvested for histomorphometric analysis from 4 cadavers from levels T3-8. A retrospective chart review was performed of all free functional muscle transfers from 2001 to 2014 by a single surgeon.

RESULTS

Rectus abdominis nerve branches provide a significant quantity of motor axons compared with high intercostal nerves and are comparable to the anterior branch of the thoracodorsal nerve and medial pectoral nerve branches. Clinically, the average recovery of elbow flexion was comparable to conventional donors for 2-stage muscle transfer.

CONCLUSION

Rectus abdominis motor nerves have similar nerve counts to thoracodorsal, medial pectoral nerves, and significantly more than high intercostal nerves alone. The use of rectus abdominis motor nerve branches allows restoration of elbow flexion comparable to other standard donors. In cases where multiple high intercostal nerves are not available as donors (rib fractures, phrenic nerve injury), rectus abdominis nerves provide a potential option for motor reconstruction without adversely affecting respiration.

Lower Extremity Reconstruction with Free Gracilis Flaps

Background There have been significant advancements in lower extremity reconstruction over the last several decades, and the plastic surgeon's armamentarium has grown to include free muscle and fasciocutaneous flaps along with local perforator and propeller flaps. While we have found a use for a variety of techniques for lower extremity reconstruction, the free gracilis has been our workhorse flap due to the ease of harvest, reliability, and low donor site morbidity. Methods This is a retrospective review of a single surgeon's series of free gracilis flaps utilized for lower extremity reconstruction. Demographic information, comorbidities, outcomes, and secondary procedures were analyzed. Results We identified 24 free gracilis flaps. The duration from injury to free flap coverage was ≤ 7 days in 6 patients, 8-30 days in 11 patients, 31-90 days in 4 patients, and > 90 days in 3 patients. There were 22 (92%) successful flaps and an overall limb salvage rate of 92%. There was one partial flap loss. Two flaps underwent incision and drainage in the operating room for infection. Two patients developed donor site hematomas. Four patients underwent secondary procedures for contouring. Our subset of pediatric patients had 100% flap survival and no secondary procedures at a mean 30-month follow-up. Conclusion This study demonstrates the utility of the free gracilis flap in reconstruction of small- to medium-sized defects of the lower extremity. This flap has a high success rate and a low donor site morbidity. Atrophy of the denervated muscle over time allows for good shoe fit, often obviating the need for secondary contouring procedures.

Robust Axonal Regeneration in a Mouse Vascularized Composite Allotransplant Model Undergoing Delayed Tissue Rejection

Background: Nerve regeneration in vascularized composite allotransplantation (VCA) is not well understood. Allogeneic transplant models experience complete loss of nerve tissue and axonal regeneration without immunosuppressive therapy. The purpose of this study was to determine the impact of incomplete immunosuppression on nerve regeneration. Methods: In this study, transgenic mice (4 groups in total) with endogenous fluorescent protein expression in axons (Thy1-YFP) and Schwann cells (S100-GFP) were used to evaluate axonal regeneration and Schwann cell (SC) migration in orthotopic-limb VCA models with incomplete immunosuppression using Tacrolimus (FK506). Survival and complication rates were assessed to determine the extent of tissue rejection. Nerve regeneration was assessed using serial imaging of axonal progression and SC migration and viability. Histomorphometry quantified the extent of axonal regeneration. Results: Incomplete immunosuppression with FK506 resulted in delayed rejection of skin, muscle, tendon, and bone in the transplanted limb. In contrast, the nerve demonstrated robust axonal regeneration and SC viability based on strong fluorescent protein expression by SCs and axons in transgenic donors and recipients. Total myelinated axon numbers measured at 8 weeks were comparable in all VCA groups and not statistically different from the syngeneic donor control group. Conclusions: Our data suggest that nerve and SCs are much weaker antigens compared with skin, muscle, tendon, and bone in VCA. To our knowledge, this study is the first to prove the weak antigenicity of nerve tissue in the orthotopic VCA mouse model.

Donor nerve sources in free functional gracilis muscle transfer for elbow flexion in adult brachial plexus injury

BACKGROUND

With complete plexus injuries or late presentation, free functional muscle transfer (FFMT) becomes the primary option of functional restoration. Our purpose is to review cases over a 10-year period of free functioning gracilis muscle transfer after brachial plexus injury to evaluate the effect of different donor nerves used to reinnervate the FFMT on functional outcome.

METHODS

A retrospective study from April 2001 to January 2011 of a single surgeon's practice was undertaken. During this time period 22 patients underwent FFMT at Washington University in St Louis, Missouri for elbow flexion.

RESULTS

Thirteen patients for whom FFMT was performed for elbow flexion met all of the requirements for inclusion in this study. Average time from injury to first operation was 12.8 months (range 4-60), and average time from injury to FFMT was 29 months (range 8-68). Average follow-up was 31.8 months (range 11-84). The nerve donors utilized included the distal accessory nerve, intercostal with or without rectus abdominis nerves, medial pectoral nerves, thoracodorsal nerve, and flexor carpi ulnaris fascicle of ulnar nerve. Functional recovery of elbow flexion was measured using the MRC grading system which showed 1 M5/5, 5 M4, 4 M3, and 3 M2 outcomes.

CONCLUSION

Intraplexal donor motor nerves if available will provide better transferred muscle function because they are higher quality donors closer to the muscle and can be done in one stage without a nerve graft. Otherwise, intercostal, rectus abdominis, or the distal accessory nerve should be used in a staged fashion. © 2016 Wiley Periodicals, Inc. Microsurgery 37:377-382, 2017.

Internal mammary artery perforator propeller flap for contralateral mastectomy defect: A case report

The internal mammary artery perforator (IMAP) flap can be used as either loco-regional or free flap, and provides thin flexible coverage for defects of the chest wall and cervical regions. In this report, we present a bilateral mastectomy case in which the left mastectomy defect was closed with an IMAP propeller flap harvested from the right breast. Our patient with a history of left breast conservation therapy was diagnosed invasive ductal carcinoma in her left breast 14 years later. On physical examination, the patient's left breast displayed the stigmata of radiotherapy including dark discoloration and firmness to palpation, compared to contralateral pendulous breast. After bilateral mastectomy, an IMAP flap with a size of 26 cm × 11 cm was harvested from right chest and was transposed 180 degrees clockwise in a propeller fashion to the left mastectomy defect without any tension. The flap survived without any complication and the patient was free of recurrence or metastases during the follow-up of 18 months. The patient was satisfied with the outcome. IMAP propeller flap could be harvested safely to the anterior axillary fold in the subcutaneous fat plane. It may provide a large skin paddle especially in large breasted women. © 2016 Wiley Periodicals, Inc. Microsurgery 36:507-510, 2016.

Free Functional Muscle Transfers to Restore Upper Extremity Function

Free functional muscle transfer provides an option for functional restoration when nerve reconstruction and tendon transfers are not feasible. To ensure a successful outcome, many factors need to be optimized, including proper patient selection, timing of intervention, donor muscle and motor nerve selection, optimal microneurovascular technique and tension setting, proper postoperative management, and appropriate rehabilitation. Functional outcomes of various applications to the upper extremity and the authors' algorithm for the use of free functional muscle transfer are also included in this article.

Motor and sensory nerve transfers in the forearm and hand

BACKGROUND

Peripheral nerve injury is a significant problem affecting more than 1 million people around the world each year and poses major challenges to the plastic and reconstructive surgeon. For high upper extremity nerve injuries, distal muscle reinnervation and functional outcomes are generally poor. Tendon transfer has been the traditional reconstructive option in these cases to restore hand function. More recently, nerve transfers have been described in the forearm and hand to recover hand and wrist function and critical sensation.

METHODS

This article reviews the surgical principles, donor nerve options, indications, and outcomes of distal nerve transfers for high upper extremity nerve injuries.

RESULTS

The functional results of nerve transfers to date have been comparable to tendon transfers. The primary advantage is the potential for individual finger motion from a donor nerve with singular function. The disadvantage is the longer recovery time required for muscle reinnervation.

CONCLUSIONS

Nerve transfers are a viable option for peripheral nerve injuries distal to the brachial plexus. The choice of management will depend on the patient's individual goals and priorities in terms of the need or desire for individual finger movement and the length of the recovery period.

Direct radial to ulnar nerve transfer to restore intrinsic muscle function in combined proximal median and ulnar nerve injury: case report and surgical technique

A distal median to ulnar nerve transfer for timely restoration of critical intrinsic muscle function is possible in isolated ulnar nerve injuries but not for combined ulnar and median nerve injuries. We used a distal nerve transfer to restore ulnar intrinsic function in the case of a proximal combined median and ulnar nerve injury. Transfer of the nonessential radial nerve branches to the abductor pollicis longus, extensor pollicis brevis, and extensor indicis proprius to the motor branch of the ulnar nerve was performed in a direct end-to-end fashion via an interosseous tunnel. This method safely and effectively restored intrinsic function before terminal muscle degeneration.

Transfer of the extensor digiti minimi and extensor carpi ulnaris branches of the posterior interosseous nerve to restore intrinsic hand function: case report and anatomic study

PURPOSE

To present a technique for restoration of ulnar intrinsic function using a nerve transfer of the extensor carpi ulnaris (ECU) and extensor digiti minimi (EDM) nerve branches of the posterior interosseous nerve (PIN) to the deep branch of the ulnar nerve in the forearm when the anterior interosseous nerve is unavailable.

METHODS

We dissected 6 cadaveric upper extremities to identify the location of the EDM and ECU branches of the PIN and their distance to the ulnar nerve near the wrist. We present a case of a high combined median and ulnar nerve injury. We performed transfer of the EDM branch and 1 of the branches to the ECU of the PIN to the motor component of the ulnar nerve for intrinsic hand function.

RESULTS

Our anatomic data demonstrate the branching pattern of the PIN and the length of regeneration and nerve graft required. Our patient required a 10-cm nerve graft, and the length of regeneration to reach the wrist was 19 cm. The patient recovered useful but incomplete reinnervation of the intrinsic muscles and rated hand recovery at 70%.

CONCLUSIONS

Transfer of the EDM and ECU branches of the PIN to the motor component of the ulnar nerve is feasible with the use of a nerve graft. Using some of the branches to the ECU as well increases the axonal load to maximize muscle reinnervation.

CLINICAL RELEVANCE

Proximal ulnar nerve injuries with paralysis of the intrinsic hand muscles lead to severe disability. Distal nerve transfers eliminate key factors that result in poor outcomes by allowing for faster muscle reinnervation. This nerve transfer had no functional donor morbidity and could be useful in the setting of a combined high median and ulnar nerve injury.

An exploration of prevalence and associated factors of nonalcoholic Fatty liver disease in the taiwanese police service

BACKGROUND

The purpose of this study was to explore any gender-related differences in prevalence of and condition-associated factors related to non-alcoholic fatty liver disease (NAFLD) amongst police population in Taipei, Taiwan.

METHODS

We studied a total of 1016 healthy adults with police work (972 males and 44 females) voluntarily admitted to physical check-up between January 2006 and December 2006. Blood samples and ultrasound-proved fatty liver sonography results were collected.

RESULTS

The prevalence of NAFLD for this sub-population was found to be 52.2%, the prevalence revealing a statistically significant decrease with increasing population age (P<0.001). Males exhibited a greater prevalence of NAFLD than did females (53.6% vs 20.5%, P<0.0001). Using multiple logistic regression analysis, in addition to male gender, an older age, higher BMI, higher ALT, presence of hyperuricemia, hypercholesterolemia, and hypertriglyceridemia were the significant factors associated with NAFLD. Gender-related differences as regards associated factors were also revealed. For males, hyperuricemia (OR=1.35, 95%CI: 1.07-1.86), higher ALT (OR=2.31, 95%CI: 1.50-3.56), hypercholesterolemia (OR=1.33, 95%CI: 1.01-1.82), and hypertriglyceridemia (OR=1.55, 95%CI: 1.01-2.37) were significantly related to NAFLD but these were not so for females.

CONCLUSION

several gender-related differences were noted pertaining to the prevalence of and relationship between hyperuricemia, higher ALT, hypercholesterolemia, and hypertriglyceridemia and NAFLD in the present study.

A novel model for evaluating nerve regeneration in the composite tissue transplant: the murine heterotopic limb transplant

PURPOSE

For individuals who have experienced debilitating upper extremity injury or amputation, hand transplantation holds the potential for drastic quality of life improvement. This potential depends on adequate nerve regeneration into the transplant and reanimation of graft musculature. In this study, we demonstrate the use of a murine heterotopic limb transplant model for evaluation of nerve regeneration in a composite tissue allograft (CTA). We also compare the effects of various immunosuppressive regimens on nerve regeneration in this model.

METHODS

The study consisted of five groups of mice, all of which underwent heterotopic limb transplant with coaptation of the recipient and donor sciatic nerves. The groups received the following immunosuppressive regimens: group A (positive control)-syngeneic transplant, no immunosuppression; group B (negative control)-allogeneic transplant, no immunosuppression; group C-allogeneic transplant, FK-506 + MR1; group D-allogeneic transplant, MR1 + CTLA4-Ig; group E-syngeneic transplant, FK-506 treatment with preloading.

RESULTS

Group B animals showed signs of transplant rejection as early as 5 days postoperatively. Except for one mouse from group C and one mouse from group D, all other animals had viable transplants and nerve regeneration present in the donor sciatic nerve at the 3-week endpoint of the study.

CONCLUSIONS

To our knowledge, this represents the first report of the use of a mouse CTA model for evaluation of nerve regeneration. The mouse heterotopic limb transplant model will be a valuable tool for CTA research since it can be performed with more ease, and with less host morbidity and mortality than the mouse orthotopic model.

The surgical management of facial nerve injury

The surgical management of facial nerve injuries is dependent upon a thorough understanding of facial nerve anatomy, nerve physiology, and microsurgical techniques. When possible, primary neurorrhaphy is the "gold standard" repair technique. Injuries resulting in long nerve gaps or a significant delay between the time of injury and repair requires alterative techniques, such as nerve grafts, nerve transfers, regional muscle transfers, free tissue transfers, and static procedures. Scrupulous technique, selection of the appropriate surgical management, and aggressive physiotherapy with motor reeducation are all critical to obtaining a functionally and aesthetically acceptable result while minimizing synkinesis and facial asymmetry. This review of the literature provides an overview of current concepts in the surgical management of facial nerve injuries.

Costimulation blockade inhibits the indirect pathway of allorecognition in nerve allograft rejection

Nerve allografts provide a temporary scaffold for host nerve regeneration. The need for systemic immunosuppression limits clinical application. Characterization of the immunological mechanisms that induce immune hyporesponsiveness may provide a basis for optimizing immunomodulating regimens. We utilized wild-type and MHC class II-deficient mice, as both recipients and donors. Host treatment consisted of triple costimulatory blockade. Quantitative assessment was made at 3 weeks using nerve histomorphometry, and muscle testing was performed on a subset of animals at 7 weeks. Nerve allograft rejection occurred as long as either the direct or indirect pathways were functional. Indirect antigen presentation appeared to be more important. Nerve allograft rejection occurs in the absence of a normal direct or indirect immune response but may be more dependent on indirect allorecognition. The indirect pathway is required to induce costimulatory blockade immune hyporesponsiveness.

Abstract P5-14-07: Noninfectious Wound Complications after Mastectomy with and without Immediate Breast Reconstruction

Background: Noninfectious wound complications, including tissue necrosis and dehiscence, may complicate healing of the breast surgical incision after mastectomy. Breast cancer patients may be at increased risk of noninfectious wound complications due to adjuvant chemo-and radiotherapy.

Objective: To identify independent risk factors for noninfectious wound complications (necrosis and/or dehiscence), including the impact of neo-and adjuvant chemotherapy, and previous and adjuvant radiotherapy after mastectomy alone or with immediate breast reconstruction. Methods: We performed a prospective cohort study of all mastectomy patients with invasive or in situ breast cancer at a tertiary care academic medical center from 8/2005 — 7/2008. Data were collected from the original surgical admission and all hospital readmissions and surgery and oncology clinic visits within 1 year of surgery. Follow-up data included documented signs and symptoms of wound complications, microbiology cultures, additional surgical procedures, and chemo-and radiation therapy dates. Extended Cox proportional hazards models were used to determine independent risk factors for wound complications, controlling for underlying comorbidities, previous chest irradiation and neoadjuvant chemotherapy, and with adjuvant radiotherapy and chemotherapy included as time-dependent covariates.

Results: 777 women had a mastectomy (408 (52.5%) mastectomy only, 325 (41.8%) mastectomy plus implant, and 44 (5.7%) mastectomy plus autologous tissue reconstruction). 173/777 women (22.3%) received neoadjuvant chemotherapy. 105 women had breast wound complications within 180 days after surgery (13.5%). Repeat surgery (incision and drainage, debridement, and/or implant removal) was required in 40/105 (38.1%) women with wound complication. 13/105 (12.4%) women had subsequent infection after wound complication, while 9/105 (8.6%) had infection diagnosed before the wound complication. Independent risk factors for noninfectious wound complication within 180 days after surgery included autologous tissue reconstruction (hazard ratio (HR) 5.6, 95% CI: 2.9-10.5), implant reconstruction (HR 4.3, 95% CI: 2.8-6.8), smoking (HR 3.3, 95% CI: 2.2-4.9), higher ASA class (HR 1.7 (95% CI: 1.0-2.9), and morbid obesity (BMI &gt; 35, HR 2.6, 95% CI: 1.7-4.0). Preadmission anticoagulant therapy was marginally associated with increased risk of necrosis/dehiscence (HR 1.8, 95% CI: 0.9-3.7). Diabetes (p = .365), neoadjuvant chemotherapy (p = .254), adjuvant chemotherapy (p = .222), previous radiotherapy (p = .195), and adjuvant radiotherapy (p = .106) were not associated with increased risk of necrosis/dehiscence within 180 days of surgery after accounting for other risk factors for wound complication. Discussion: Immediate breast reconstruction, smoking, and morbid obesity were associated with increased risk of tissue necrosis/dehiscence within 180 days after mastectomy. Neo-and adjuvant chemotherapy and adjuvant radiotherapy were not associated with increased risk of noninfectious wound complications after controlling for underlying comorbidities and other risk factors. These results emphasize the important of smoking cessation in women undergoing mastectomy, particularly with immediate breast reconstruction.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-14-07.

Effect of cold nerve allograft preservation on antigen presentation and rejection

OBJECT

Nerve allotransplantation provides a temporary scaffold for host nerve regeneration and allows for the reconstruction of significant segmental nerve injuries. The need for systemic immunosuppression, however, limits the current clinical utilization of nerve allografts, although this need is reduced by the practice of cold nerve allograft preservation. Activation of T cells in response to alloantigen presentation occurs in the context of donor antigen presenting cells (direct pathway) or host antigen-presenting cells (indirect pathway). The relative role of each pathway in eliciting an alloimmune response and its potential for rejection of the nerve allograft model has not previously been investigated. The objective of this investigation was to study the effect of progressive periods of cold nerve allograft preservation on antigen presentation and the alloimmune response.

METHODS

The authors used wild type C57Bl/6 (B6), BALB/c, and major histocompatibility Class II-deficient (MHC-/-) C57Bl/6 mice as both nerve allograft recipients and donors. A nonvascularized nerve allograft was used to reconstruct a 1-cm sciatic nerve gap. Progressive cold preservation of donor nerve allografts was used. Quantitative assessment was made after 3 weeks using nerve histomorphometry.

RESULTS

The donor-recipient combination lacking a functional direct pathway (BALB/c host with MHC-/- graft) rejected nerve allografts as vigorously as wild-type animals. Without an intact indirect pathway (MHC-/- host with BALB/c graft), axonal regeneration was improved (p < 0.052). One week of cold allograft preservation did not improve regeneration to any significant degree in any of the donor-recipient combinations. Four weeks of cold preservation did improve regeneration significantly (p < 0.05) for all combinations compared with wild-type animals without pretreatment. However, only in the presence of an intact indirect pathway (no direct pathway) did 4 weeks of cold preservation improve regeneration significantly compared with 1 week and no preservation in the same donor-recipient combination.

CONCLUSIONS

The indirect pathway may be the predominant route of antigen presentation in the unmodified host response to the nerve allograft. Prolonged duration of cold nerve allograft preservation is required to significantly attenuate the rejection response. Cold preservation for 4 weeks improves nerve regeneration with a significant effect on indirect allorecognition.

Multiple costimulatory blockade in the peripheral nerve allograft

BACKGROUND

In the nerve allograft model, costimulation blockade has permitted good regeneration but is still inferior to the nerve isograft. We hypothesize that a short course of multiple costimulatory pathway blockade will be more effective in inhibiting the redundancy of the immune response and improve nerve regeneration through the nerve allograft.

METHODS

The murine sciatic nerve allograft model was used to reconstruct a 1 cm sciatic nerve gap. Treatment consisted of the inhibition of the CD40, CD28/B7 and ICOS pathways and was compared with only single or double costimulation blockade. Assessment methods included quantitative histomorphometry and ELISPOT assay to quantify the host immune response after 3 weeks post-operatively.

RESULTS

Triple costimulation blockade permitted regeneration through the nerve allograft that was equivalent to the nerve isograft. A short course of three doses was more effective than a single dose for all combinations tested. ELISPOT assay demonstrated minimal in vitro immune response with a short course of double or triple pathway-blocking agents.

CONCLUSION

Costimulation blockade, especially with the simultaneous inhibition of multiple pathways, remains a promising strategy to promote regeneration through the peripheral nerve allograft, and may be uniquely suited to the temporary immunosuppressive requirements of the peripheral nerve allograft.

Tacrolimus (FK506): Safety and Applications in Reconstructive Surgery

Tacrolimus (FK506) is a macrolide immunosuppressive drug that is approved for the prevention of allograft rejection. It is a standard component of immunosuppressive regimens currently in use for organ and reconstructive tissue transplants. The experimental literature has demonstrated potential efficacy in the management of other diseases for which transplantation does not play a role. The ability of tacrolimus to modulate the immune system and inhibit T cell activation provides a potential benefit for the treatment of disorders in which autoimmune phenomena are central to their pathogenesis such as rheumatoid arthritis and inflammatory bowel disease. Tacrolimus also has well-established neuroprotective and neuroregenerative properties through both similar and different mechanisms that have been extensively demonstrated in both small and large animal models. However, as a potent immunosuppressive agent, it can cause serious adverse effects, some of which are irreversible and potentially life threatening. This article reviews its safety under different therapeutic requirements and applications in both allogeneic and autogenous tissue reconstruction.

The role of T helper cell differentiation in promoting nerve allograft survival with costimulation blockade

OBJECT

Peripheral nerve allografts provide a temporary scaffold for host nerve regeneration and allow for the repair of significant segmental nerve injuries. Despite this potential, nerve allograft transplantation requires temporary systemic immunosuppression. Characterization of the immunological mechanisms involved in the induction of immune hyporesponsiveness to prevent nerve allograft rejection will help provide a basis for optimizing immunomodulation regimens or manipulating donor nerve allografts to minimize or eliminate the need for global immunosuppression.

METHODS

The authors used C57Bl/6 mice and STAT4 and STAT6 gene BALB/c knockout mice. A nonvascularized nerve allograft was used to reconstruct a 1-cm sciatic nerve gap in the murine model. A triple costimulatory blockade of the CD40, CD28/B7, and inducible costimulatory (ICOS) pathways was used. Quantitative assessment was performed at 3 weeks with nerve histomorphometry, walking track analysis, and the enzyme-linked immunospot assay.

RESULTS

The STAT6 -/- mice received 3 doses of costimulation-blocking antibodies and had axonal regeneration equivalent to nerve isografts, while treated STAT4 -/- mice demonstrated moderate axonal regeneration but inferior to the T helper cell Type 2-deficient animals. Enzyme-linked immunospot assay analysis demonstrated a minimal immune response in both STAT4 -/- and STAT6 -/- mice treated with a costimulatory blockade.

CONCLUSIONS

The authors' findings suggest that Type 1 T helper cells may play a more significant role in costimulatory blockade-induced immune hyporesponsiveness in the nerve allograft model, and that Type 2 T helper differentation may represent a potential target for directed immunosuppression.

Nerve transfers: indications, techniques, and outcomes

This article provides an update of the current strategies of motor and sensory nerve transfers for peripheral nerve lesions of the upper extremity. Indications, techniques, and outcomes are summarized for both well-established transfers used in the management of proximal and brachial plexus injuries as well as those more recently developed for more distal and isolated nerve injuries in the forearm and hand.

Nerve transfer for elbow flexion in radiation-induced brachial plexopathy: a case report

Radiation-induced brachial plexopathy is an uncommon but devastating late complication seen in patients receiving radiation therapy to the chest wall and axilla. Treatment options are unfortunately limited. We report a case of a 59-year-old woman treated with radiation therapy for breast cancer 12 years earlier, who presented with loss of elbow flexion and marked shoulder weakness. Electromyogram and intraoperative stimulation of the musculocutaneous nerve branches were consistent with a proximal motor nerve conduction block. Microsurgical transfer of median and ulnar nerve fascicles to the biceps and brachialis branches of the musculocutaneous nerve, respectively, were performed. The patient recovered MRC grade 4/5 elbow flexion after surgery. The characteristics of this disorder and surgical treatment options are reviewed.

Motor nerve transfers to restore extrinsic median nerve function: case report

Active pronation is important for many activities of daily living. Loss of median nerve function including pronation is a rare sequela of humerus fracture. Tendon transfers to restore pronation are reserved for the obstetrical brachial plexus palsy patient. Transfer of expendable motor nerves is a treatment modality that can be used to restore active pronation. Nerve transfers are advantageous in that they do not require prolonged immobilization postoperatively, avoid operating within the zone of injury, reinnervate muscles in their native location prior to degeneration of the motor end plates, and result in minimal donor deficit. We report a case of lost median nerve function after a humerus fracture. Pronation was restored with transfer of the extensor carpi radialis brevis branch of the radial nerve to the pronator teres branch of the median nerve. Anterior interosseous nerve function was restored with transfer of the supinator branch to the anterior interosseous nerve. Clinically evident motor function was seen at 4 months postoperatively and continued to improve for the following 18 months. The patient has 4+/5 pronator teres, 4+/5 flexor pollicis longus, and 4-/5 index finger flexor digitorum profundus function. The transfer of the extensor carpi radialis brevis branch of the radial nerve to the pronator teres and supinator branch of the radial nerve to the anterior interosseous nerve is a novel, previously unreported method to restore extrinsic median nerve function.

Treatment modality affects allograft-derived Schwann cell phenotype and myelinating capacity

We used peripheral nerve allografts, already employed clinically to reconstruct devastating peripheral nerve injuries, to study Schwann cell (SC) plasticity in adult mice. By modulating the allograft treatment modality we were able to study migratory, denervated, rejecting, and reinnervated phenotypes in transgenic mice whose SCs expressed GFP under regulatory elements of either the S100b (S100-GFP) or nestin (Nestin-GFP) promoters. Well-differentiated SCs strongly expressed S100-GFP, while Nestin-GFP expression was stimulated by denervation, and in some cases, axons were constitutively labeled with CFP to enable in vivo imaging. Serial imaging of these mice demonstrated that untreated allografts were rejected within 20 days. Cold preserved (CP) allografts required an initial phase of SC migration that preceded axonal regeneration thus delaying myelination and maturation of the SC phenotype. Mice immunosuppressed with FK506 demonstrated mild subacute rejection, but the most robust regeneration of myelinated and unmyelinated axons and motor endplate reinnervation. While characterized by fewer regenerating axons, mice treated with the co-stimulatory blockade (CSB) agents anti-CD40L mAb and CTLAIg-4 demonstrated virtually no graft rejection during the 28 day experiment, and had significant increases in myelination, connexin-32 expression, and Akt phosphorylation compared with any other group. These results indicate that even with SC rejection, nerve regeneration can occur to some degree, particularly with FK506 treatment. However, we found that co-stimulatory blockade facilitate optimal myelin formation and maturation of SCs as indicated by protein expression of myelin basic protein (MBP), connexin-32 and phospho-Akt.

Median to radial nerve transfer for treatment of radial nerve palsy. Case report

The purpose of this study is to report a surgical technique of nerve transfer to restore radial nerve function after a complete palsy due to a proximal injury to the radial nerve. The authors report the case of a patient who underwent direct nerve transfer of redundant or expendable motor branches of the median nerve in the proximal forearm to the extensor carpi radialis brevis and the posterior interosseous branches of the radial nerve. Assessment included degree of recovery of wrist and finger extension, and median nerve function including pinch and grip strength. Clinical evidence of reinnervation was noted at 6 months postoperatively. The follow-up period was 18 months. Recovery of finger and wrist extension was almost complete with Grade 4/5 strength. Pinch and grip strength were improved postoperatively. No motor or sensory deficits related to the median nerve were noted, and the patient is very satisfied with her degree of functional restoration. Transfer of redundant synergistic motor branches of the median nerve can successfully reinnervate the finger and wrist extensor muscles to restore radial nerve function. This median to radial nerve transfer offers an alternative to nerve repair, graft, or tendon transfer for the treatment of radial nerve palsy.

Induction of Regional Collateral Sprouting Following Muscle Denervation

OBJECTIVES/HYPOTHESIS

Anecdotal clinical findings suggest that denervated muscle may regain modest functional recovery via spontaneous collateral sprouts from intact adjacent nerve fibers. The current study evaluates the conditions needed for the denervated masseter muscle to induce axonal sprouting from the facial nerve. We hypothesize that epineurial injury is required to induce collateral sprouting toward a neighboring denervated muscle.

STUDY DESIGN

Twelve thy1-yellow fluorescent protein-16 (thy1-YFP-16) transgenic mice whose axons express yellow fluorescent protein were allocated into six groups, with four degrees of facial nerve injury (intact, crush, transection, removed segment) with or without masseter denervation.

METHODS

Animals underwent serial in vivo imaging analyses under the fluorescent microscope weekly for 5 or 7 weeks and were subsequently perfused for analysis. Masseter muscle acetylcholine receptors (AChRs) were stained with Alexa Fluor 594 conjugated alpha-bungarotoxin, and whole mounts were imaged with confocal microscopy.

RESULTS

In groups with intact or crushed facial nerves, no evidence of collateral sprouting was demonstrated. Mice with transected facial nerve branches or removed segments demonstrated sprouting from the proximal stump into the denervated masseter. Staining of the AChRs confirmed that new neuromuscular junctions were established between the facial nerve and the denervated masseter.

CONCLUSIONS

This study suggests that epineurial injury is required to stimulate axonal sprouting into adjacent denervated muscle. Nerves with compromised epineurium may be useful in promoting neo-neurotization after muscle denervation.

Median to radial nerve transfer for treatment of radial nerve palsy. Case report

The purpose of this study is to report a surgical technique of nerve transfer to restore radial nerve function after a complete palsy due to a proximal injury to the radial nerve. The authors report the case of a patient who underwent direct nerve transfer of redundant or expendable motor branches of the median nerve in the proximal forearm to the extensor carpi radialis brevis and the posterior interosseous branches of the radial nerve. Assessment included degree of recovery of wrist and finger extension, and median nerve function including pinch and grip strength. Clinical evidence of reinnervation was noted at 6 months postoperatively. The follow-up period was 18 months. Recovery of finger and wrist extension was almost complete with Grade 4/5 strength. Pinch and grip strength were improved postoperatively. No motor or sensory deficits related to the median nerve were noted, and the patient is very satisfied with her degree of functional restoration. Transfer of redundant synergistic motor branches of the median nerve can successfully reinnervate the finger and wrist extensor muscles to restore radial nerve function. This median to radial nerve transfer offers an alternative to nerve repair, graft, or tendon transfer for the treatment of radial nerve palsy.

Use of motor nerve material in peripheral nerve repair with conduits

We have recently shown in experimental nerve injury models that nerve regeneration is enhanced across a motor nerve graft as compared with a sensory nerve graft. To test the hypothesis that nerve architecture may mediate the beneficial effect of motor nerve grafting, we developed a model of disrupted nerve architecture in which motor and sensory nerve fragments were introduced into silicone conduits. Lewis rats were randomized to 5 experimental groups: nerve repair with motor nerve fragments, sensory nerve fragments, mixed nerve fragments, saline-filled conduit (negative control), or nerve isograft (positive control). At 6, 9, or 12 weeks, animals were sacrificed and nerve tissues were analyzed by quantitative histomorphometry. No significant differences were observed between the motor, sensory, and mixed nerve fragment groups. These findings suggest that intact nerve architecture, regardless of neurotrophic or biochemical factors, is a prerequisite for the beneficial effect of motor nerve grafting.

Survival of long nerve allografts following donor antigen pretreatment: a pilot study

In this study, the authors evaluated whether the pretransplant portal venous administration of UV-B irradiated donor alloantigen would induce tolerance to long peripheral nerve allografts in a swine model. They completed nerve allograft transplantation between four swine of separate lineages. Regeneration across the nerve allografts was followed for 10 months postoperatively. Sequential IN VITRO assays demonstrated the successful and prolonged suppression of the recipient immune response to donor antigen following antigen inoculation. Histomorphometric analysis demonstrated successful regeneration across the long nerve allografts in the pretreated recipients, but not across allografts in unimmunosuppressed recipients. A single pretransplant antigen delivery protocol has the potential to replace chronic medicinal immunosuppressant therapy and its associated morbidities. Furthermore, tolerance to long nerve allografts has immediate applicability to clinical requirements for bridging multiple, complex, long nerve gaps.

Traumatic brachial plexus injuries

Brachial plexus injuries can be difficult to diagnose and manage. A combination of injury history, as well as radiology, electrodiagnostics, and physical exam skills can aid in this diagnosis. While some patients will regain function spontaneously, many require surgical reconstruction. Surgical options have changed with technological advances in microsurgery, and the availability of long-term outcome data following plexus reconstruction.

Chimerism after Vascularized Limb Versus Bone Marrow Transplantation

This study used quantitative PCR in the murine model to compare the ability of a limb allograft vs. a comparable dose of marrow suspension to induce chimerism. Female C57Bl/6 mice received a vascularized hindlimb allograft, a comparable dose of 5 x 10 (6) donor bone marrow cells, or a standard dose (20 x 10 (6)) of marrow suspension from male Balb/c donors. All recipients were treated with a regimen based on CD40 costimulation blockade and T cell depletion. Y chromosome-specific quantitative PCR was used to measure chimerism. Most recipients of limb allografts demonstrated low levels of chimerism after 1 week (3/4) and 1 month (3/4). Most recipients of 5 x 10 (6) marrow cells had low levels of chimerism at 1 week (4/6) and only 1/5 after 1 month. All recipients of 20 x 10 (6) cells except one demonstrated either low or high levels of chimerism after 1 week (5/5) and 1 month (5/6). The marrow component of a limb allograft is thus more effective at inducing microchimerism compared to a comparable dose of bone marrow suspension.

Combined Treatment with CD40 Costimulation Blockade, T-Cell Depletion, Low-Dose Irradiation, and Donor Bone Marrow Transfusion in Limb Allograft Survival

To determine the efficacy of a regimen based on CD40 costimulation blockade and donor bone marrow in the limb allograft model, C57Bl/6 mice received limb allografts from Balb/c mice and either no treatment or a combination of MR1 (anti-CD40 ligand monoclonal antibody), CD4+ and CD8+ T-cell-depleting antibodies, low-dose irradiation, and bone marrow transfusion from Balb/c donors for 1 or 2 weeks. Recipients treated for 1 week showed rejection at 38.2 +/- 5.4 (mean +/- SEM) days, while those treated for 2 weeks had allograft survival of 56.5 +/- 9.9, with a range up to 91 days. Histology demonstrated rejection which was less cell-mediated and suggestive of transplant vasculopathy. Differential rejection of skin occurred first. Thus, a combined regimen based on CD40 costimulatory blockade and donor marrow significantly prolonged allograft survival. However, tolerance was not achieved, and histology suggests chronic rejection as a possible cause of allograft loss.

Nerve reconstruction in lumbosacral plexopathy. Case report and review of the literature

Neurological injury to the lumbosacral plexus associated with pelvic and sacral fractures has traditionally been treated conservatively, despite significant and often debilitating functional deficits of the lower extremities. The authors report a case of reconstruction of the lumbosacral plexus, including nerve grafting to restore lower-extremity function caused by severe trauma to the pelvis. A 16-year-old boy sustained pelvic and sacral fractures in a motor vehicle accident. After stabilization of his orthopedic injuries, he suffered from paresis of his right gluteal and hamstring muscles and had no motor or sensory function below his knee. Two months later, he underwent reconstruction of his lumbosacral plexus performed using a nerve graft from his L-5 and S-1 nerve roots proximal to the inferior gluteal nerve and distal to a branch to the hamstring muscles. After another 2 months, his recovering saphenous nerve was transferred to the sensory component of the posterior tibial nerve by using cabled sural nerve grafts to restore sensation to the sole of his foot. After 2.5 years, he experienced reinnervation of his gluteal and hamstring muscles and could perceive vibration on the sole of his foot. With the assistance of a foot-drop splint, the patient ambulates well and is able to ski. Operative details and the relevant literature are reviewed.

Results of reinnervation of the biceps and brachialis muscles with a double fascicular transfer for elbow flexion

PURPOSE

To report the results of a surgical technique of nerve transfer to reinnervate the brachialis muscle and the biceps muscle to restore elbow flexion after brachial plexus injury.

METHODS

Retrospective review was performed on 6 patients who had direct nerve transfer of a single expendable motor fascicle from both the ulnar and median nerves directly to the biceps and brachialis branches of the musculocutaneous nerve. Assessment included degree of recovery of elbow flexion and ulnar and median nerve function including pinch and grip strengths.

RESULTS

Clinical evidence of reinnervation was noted at a mean of 5.5 months (SD, 1 mo; range, 3.5-7 mo) after surgery and the mean follow-up period was 20.5 months (SD, 11.2 mo, range, 13-43 mo). Mean recovery of elbow flexion was Medical Research Council grade 4+. Postoperative pinch and grip strengths were unchanged or better in all patients. No motor or sensory deficits related to the ulnar or median nerves were noted and all patients maintained good hand function. No patients required additional procedures to further improve elbow flexion strength.

CONCLUSIONS

Transfer of expendable motor fascicles from the ulnar and median nerves successfully can reinnervate the biceps and brachialis muscles for strong elbow flexion. The reinnervation of the brachialis muscle, the primary elbow flexor, as well as the biceps muscle provides an additional biomechanical advantage that accounts for the excellent elbow flexion strength obtained using this technique. Direct coaptation of the nerve fascicles was performed without the need for nerve grafts and there was no functional or sensory donor morbidity.

Th1/Th2 Cytokine Profile of the Immune Response in Limb Component Transplantation

BACKGROUND

The purpose of this study was to define the cytokine secretion pattern during limb allograft rejection and to determine its correlation to differential tissue antigenicity of limb allograft components.

METHODS

Twenty-five C57Bl/6 mice (H-2Kb) were randomized to six groups. The experimental groups were recipients of vascularized Balb/c mice (H-2Kd) allografts consisting of skin, muscle, whole limb, or limb with the skin removed or nonvascularized nerve allografts. The unmodified rejection response was studied by histology, flow cytometry, and ELISPOT assay to quantify IFN-gamma (Th1) and IL-4 (Th2) production.

RESULTS

The greatest Th1 response was seen in the recipients of allografts composed of skin (973.3 +/- 93 spots/million spleen cells; mean +/- SEM), followed by whole limb (961.3 +/- 86/million), nerve (613.3 +/- 245/million), limb with skin removed (483 +/- 246/million), and then muscle (460 +/- 234/million). Recipients of skin, whole limb, and nerve allografts had the highest IFN-gamma:IL-4 ratios, or greatest Th1 deviation, of 3.1 +/- 0.4, 3.0 +/- 0.2, and 2.9 +/- 0.6, respectively. These were significantly greater than those that received muscle (0.9 +/- 0.3) and limb allografts with skin removed (1.0 +/- 0.4) (p < 0.05).

CONCLUSIONS

The skin component produced the greatest Th1 activation of the immune response and appears to be a critical component of the overall antigenicity of the whole limb allograft, as evidenced by the Th2 shift seen when the skin was removed. Muscle produced the least Th1 differentiation, with nerve being intermediate.

Effect of FK506 on Peripheral Nerve Regeneration Through Long Grafts in Inbred Swine

Numerous small-animal studies have demonstrated that FK506 enhances nerve regeneration and accelerates functional recovery after nerve injury. However, no experimental study has corroborated these neuroregenerative effects in larger animals. This study investigated the effects of FK506 on nerve regeneration in inbred miniature swine. Eight animals received 8-cm ulnar nerve autografts and allografts. Treated animals received 0.1 to 0.4 mg/kg FK506 injections twice weekly to maintain immunosuppressive serum FK506 levels. At 24 weeks posttransplant, nerve grafts were harvested for histomorphometric analysis. Mixed lymphocyte cultures demonstrated alloreactivity in 1 treated animal and all untreated animals. In autografts, mean fiber count, nerve density, and percent neural tissue were doubled with FK506 therapy. In allografts, significant neuroregeneration was observed in animals treated with FK506, whereas untreated animals had no regeneration. Treatment with FK506 resulted in a trend toward enhanced axonal regeneration through nerve autografts and allografts in a large-animal model with defined histocompatibility barriers.

Prolonged limb allograft survival with CD40 costimulation blockade, T-cell depletion, and megadose donor bone-marrow transfusion

The purpose of this study was to determine the efficacy of a treatment regimen consisting of CD 40 costimulation blockade, T-cell depletion, and megadose donor bone marrow transfusion in the limb allograft model. C57Bl/6 mice underwent limb transplantation from Balb/c mice and received MR1 (anti-CD 40 ligand monoclonal antibody), and CD4(+) and CD8(+) T cell-depleting antibodies with and without 120 x 10(6) donor bone-marrow transfusion. Recipients treated only with antibodies showed rejection at 51.4+/-17 (mean+/-SEM) days, while those who also received donor bone marrow had allograft survival of 67+/-16.4 days, with a range up to 91 days. Treated specimens with rejection had less lymphocytic infiltration than untreated controls. Recipients of donor bone marrow also demonstrated early mixed chimerism, which disappeared after 1 month. While allograft survival was prolonged, tolerance was not achieved, and the mechanism of rejection was more consistent with a chronic process.

Effects of motor versus sensory nerve grafts on peripheral nerve regeneration

Autologous nerve grafting is the current standard of care for nerve injuries resulting in a nerve gap. This treatment requires the use of sensory grafts to reconstruct motor defects, but the consequences of mismatches between graft and native nerve are unknown. Motor pathways have been shown to preferentially support motoneuron regeneration. Functional outcome of motor nerve reconstruction depends on the magnitude, rate, and precision of end organ reinnervation. This study examined the role of pathway type on regeneration across a mixed nerve defect. Thirty-six Lewis rats underwent tibial nerve transection and received isogeneic motor, sensory or mixed nerve grafts. Histomorphometry of the regenerating nerves at 3 weeks demonstrated robust nerve regeneration through both motor and mixed nerve grafts. In contrast, poor nerve regeneration was seen through sensory nerve grafts, with significantly decreased nerve fiber count, percent nerve, and nerve density when compared with mixed and motor groups (P < 0.05). These data suggest that use of motor or mixed nerve grafts, rather than sensory nerve grafts, will optimize regeneration across mixed nerve defects.

Nerve transfers to the biceps and brachialis branches to improve elbow flexion strength after brachial plexus injuries

Object

In this study the authors evaluated the outcome in patients with brachial plexus injuries who underwent nerve transfers to the biceps and the brachialis branches of the musculocutaneous nerve.

Methods

The charts of eight patients who underwent an ulnar nerve fascicle transfer to the biceps branch of the musculocutaneous nerve and a separate transfer to the brachialis branch were retrospectively reviewed. Outcome was assessed using the Medical Research Council (MRC) grade to classify elbow flexion strength in conjunction with electromyography (EMG).

The mean patient age was 26.4 years (range 16–45 years) and the mean time from injury to surgery was 3.8 months (range 2.5–7.5 months). Recovery of elbow flexion was MRC Grade 4 in five patients, and Grade 4+in three. Reinnervation of both the biceps and brachialis muscles was confirmed on EMG studies. Ulnar nerve function was not downgraded in any patient.

Conclusions

The use of nerve transfers to reinnervate the biceps and brachialis muscle provides excellent elbow flexion strength in patients with brachial plexus nerve injuries.

Immune unresponsiveness by intraportal UV-B-irradiated donor antigen administration requires persistence of donor antigen in a nerve allograft model

The purpose of this study was to characterize the mechanism of unresponsiveness produced by the intraportal administration of ultraviolet-B (UV-B)-irradiated donor antigen. Pretreated Buffalo rats accepted Lewis nerve allografts, had decreased in vitro T-cell reactivity, and demonstrated nerve regeneration and recovery of limb function, while rejecting third-party nerve allografts. Regenerated nerve grafts were then retransplanted into a second naïve recipient. Rejection of the retransplanted allograft by naïve donor-strain, but not recipient-strain, animals suggests that the allografts were completely replaced by host tissue. Pretreated Buffalo rats were also given a second Lewis allograft after the first had regenerated. The second allograft was rejected and in vitro immune reactivity was comparable to naïve animals. Because the unresponsiveness state was extinguished with loss of exposure to donor antigen, these findings suggest that the intraportal administration of UV-B-irradiated donor antigen works by anergic or suppressive regulatory, rather than deletional, mechanisms.

Strain differences in autotomy in mice after peripheral nerve transection or repair

The purpose of this study was to identify the optimal murine model for the study of peripheral nerve injury and nerve and limb transplantation. The degree of self-mutilation (autotomy) following sciatic and saphenous nerve injury was assessed in four mouse strains, Balb/C, C57BL/6J, C57BL/10J, and C3HEB, commonly used in surgical research. Experimental groups included sciatic and saphenous nerve transection with repair (n = 9) or without repair (n = 9), as well as housing arrangements favoring social interaction vs. isolation. Autotomy was most prevalent in the Balb/c and C3H strains at 56% and 89% overall, respectively, and was much less frequently seen in the C57Bl/10 and C57Bl/6 strains (22% and 11%, respectively). Autotomy was found to correlate most strongly with mouse strain, and with social contact as well. Two strains, C57BL/6J and C57BL/10J, were found to be highly resistant to self-mutilation, and are thus ideal animal models for peripheral-nerve and whole-limb transplant studies.