Contributions of neural tone to in vivo passive muscle--tendon unit biomechanical properties in a rat rotator cuff animal model

Passive viscoelastic properties of muscle–tendon units are key determinants of intra- and post-operative success. Atrophied, retracted, and stiff muscle–tendon units are technically challenging to manipulate and perform poorly after surgical repair. This study employs botulinum neurotoxin A (BoNT-A)-mediated inhibition of presynaptic acetylcholine release to examine in vivo neural contributions to soft-tissue biomechanical properties. In vivo load-relaxation and active muscle contractile force testing protocols were performed in the rat rotator cuff model. The passive properties were assessed using linear regression analysis and Fung’s quasi-linear viscoelastic (QLV) model. BoNT-A injected muscle–tendon units had a significant reduction in force of contraction (p = 0.001). When compared to saline injected controls, the BoNT-A significantly decreased parameter ‘A’ of the QLV model, which represents the linear elastic response (p = 0.032). The viscous properties in the BoNT-A treatment group were not significantly different from saline injected controls, as determined by comparison of QLV model parameters ‘C,’ ‘τ₁,’ and ‘τ₂.’ In conclusion, neural tone contributes significantly to muscle–tendon unit passive biomechanical properties. Pre-surgical treatment with BoNT-A may improve the rehabilitation of muscle by altering its passive elastic properties. Accordingly, pharmacological modulation of skeletal muscle stiffness with BoNT-A increases flexibility, potentially improving function. Chemical denervation with BoNT-A may also improve the manipulation of stiff and difficult to mobilize muscles during surgical procedures.     

Thermoregulatory abnormalities of the foot

Thermoregulatory abnormalities are well known but poorly understood phenomena. Pathologic alterations of microvascular blood flow occur in a variety of diseases of the foot, and often cause severe functional impairment. The structure, function, and methods for testing thermoregulatory abnormalities are reviewed. Pathologic manifestations of abnormal thermoregulation are also discussed.     

Salvage of lower extremities following combined orthopedic and vascular trauma. A predictive salvage index

A retrospective review of 676 tibial-fibular fractures and 985 femoral fractures treated over a 71-month period yielded associated major vascular trauma in 12 (1.7%) tibial-fibular fractures and in five (0.5%) femoral fractures. Vascular trauma combined with orthopedic trauma was also identified in four other cases--two disruptions of the pubic symphysis and two dislocations of the knee without fracture. Nine (43%) of the 21 involved limbs were eventually amputated. Limb survival was not related to the temporal relationship of vessel repair to skeletal stabilization; the presence or absence of shock on admission; the presence of associated but repaired venous injury; or the presence of unrelated injuries. Limb survival was related to the interval from injury to arrival in the operating room; the level of arterial injury; and the quantitative degree of muscle, bone, and skin injury. By combining these variables a limb salvage index was established that identified lower extremities likely to require amputation after combined orthopedic and vascular trauma (sensitivity 78%, specificity 100%). Use of this predictive salvage index may prevent the trauma surgeon from attempting to salvage a doomed or useless lower extremity and may thus permit early prosthetic rehabilitation to follow definitive primary amputation.     

Factors associated with self-esteem in pre-adolescents and adolescents with cerebral palsy

Predictors of self-esteem were examined in 50 pre-adolescents and adolescents with cerebral palsy. On average, self-esteem was high, although 30% scored below a cut-point for low self-esteem. Self-esteem was bivariately associated with female gender, better physician-assessed functional ability, greater perception of the impact of the disability, and higher perceived parent overprotectiveness. In a multivariate model, only perceived impact of the disability remained significant.     

Thermoregulatory control after upper extremity replantation

Four patients with complete forearm amputations between the wrist and elbow were analyzed prospectively to determine the interrelationships of thermoregulation to pain, cold intolerance, arterial integrity, venous competence, motor nerve recovery, sensory nerve recovery, and time. Patients were examined at 6 weeks, 3 months, 6 months, 1 year, and 2 years after replantation. Vasomotor regulatory capacity was assessed by isolated cold-stress testing. Pain had diminished in all patients by 6 months to 1 year, regardless of other factors. Cold tolerance and normal thermoregulatory response, as indicated by cold-stress test performances, were temporally related to attainment of two-point sensory discrimination (p less than 0.05), or to motor nerve recovery (p less than 0.05), or to both.     

Free flaps for coverage of the foot and ankle

Coverage of complex soft tissue injuries to the foot and ankle is difficult and often can be achieved only by the use of free flaps. Selection of the appropriate flap must be patient-oriented. Indications for composite tissue transfer are presented. In addition, the vascular anatomy and characteristics of commonly used flaps--the groin flap, the scapular flap, and the latissimus dorsi, tensor fascia lata, and gracilis flaps are presented along with case histories illustrating their utilization.     

Longitudinal examination of health outcomes associated with botulinum toxin use in children with cerebral palsy

A prospective cohort study with annual follow-up was conducted on 172 children with spastic type cerebral palsy receiving botulinum toxin type A (BTX) injections for spasticity management. A mixed modeling procedure was used to identify changes in both physical functioning outcomes for the child (using the WeeFIM measure) as well as quality of life of the parent caregiver (using the Stein and Reissman Impact on the Family Scale) with increasing utilization of BTX injections. The study found that each additional BTX injection administration was associated with a 2.3% improvement in the WeeFIM compared to the average baseline score (p < .01). Similarly, the study found an improvement of 2.5% compared to baseline in the parent's overall perception of the severity of the child's condition with each additional BTX injection administration (p < .001). These findings suggest that BTX injections may be associated with beneficial outcomes in childhood spasticity.     

Complex regional pain syndrome (reflex sympathetic dystrophy)

The management of CRPS can be approached using objective criteria in a logical and systematic fashion. Frustration during treatment is common because: (1) the pathophysiology of CRPS is incompletely understood, (2) there is significant variation in presentation due to disparate premorbid anatomy and physiology, and (3) the natural history may be affected by incomplete treatment. Therapeutic efforts that should be effective may fail, and a trial-and-error approach to treatment is often mandatory. Early recognition of CRPS and prompt intervention, however, provide the best opportunity for clinical improvement.