Intrinsic contractures of the thumb

Recognizing and managing upper extremity compartment syndrome

Compartment syndrome is an acute limb-threatening condition typically treated with emergency fasciotomy. Although limbs often are saved, ischemia can cause irreversible neurologic damage to the extremity. Patients with upper extremity compartment syndrome may lose fine motor function, which can result in long-term impairment of perceived quality of life. This article reviews the anatomy, physiology, presentation, diagnosis, and treatment of upper extremity compartment syndrome, including rehabilitation, which can reduce complications that occur even in patients who were promptly and properly treated.

Transcutaneous high-frequency alternating current for rapid reversible muscle force reduction below pain threshold

OBJECTIVE

The development of non-invasive, quickly reversible techniques for controlling undesired muscle force production (e.g. spasticity) could expand rehabilitation approaches in those with pathology by increasing the type and intensity of exercises that can be performed. High-frequency alternating current (HFAC) has been previously established as a viable method for blocking neural conduction in peripheral nerves. However, clinical application of HFAC for nerve conduction block is limited due to the invasiveness of surgical procedures and the painful onset response. This study aimed to examine the use of transcutaneous HFAC (tHFAC) at various stimulation frequencies to address these shortfalls.

APPROACH

Ten individuals participated in the study. Surface electrodes were utilized to apply tHFAC (0.5-12 kHz) to the median and ulnar nerves. Individual pain threshold was determined by gradual increase of stimulation amplitude. Subjects then performed a force-matching task by producing grip forces up to the maximal voluntary contraction level with and without application of tHFAC below the pain threshold.

MAIN RESULTS

Pain threshold current amplitude increased linearly with stimulation frequency. Statistical analysis showed that both stimulation frequency and charge injected per phase had significant effects (p   <  0.05) on grip force reduction. At the group level, application of tHFAC below pain threshold reduced grip force by a maximum of 40.7%  ±  8.1%. Baseline grip force trials interspersed between tHFAC trials showed consistent grip force, indicating that fatigue was not a factor in force reduction.

SIGNIFICANCE

Our results demonstrate the effectiveness of tHFAC at reducing muscle force when applied below the pain threshold, suggesting its potential clinical viability. Future studies are necessary to further elucidate the mechanism of force reduction before clinical application.

Intracompartmental Versus Extracompartmental Transposition of the Extensor Pollicis Longus for Treating Thumb-in-Palm Deformity: A Biomechanical Comparison

PURPOSE

Transecting the extensor pollicis longus (EPL) tendon and rerouting it through the first extensor compartment is an established technique for treating thumb-in-palm deformity (TIPD). An alternative technique that approximates the trajectory of the first extensor compartment without violating the compartment or transecting the EPL tendon can be accomplished by creating an artificial sheath from the extensor retinaculum to radialize the tendon glide path. This study compares this extracompartmental (EC) EPL transposition to the established, intracompartmental (IC) transposition by evaluating, in a cadaver model, the extent of thumb extension in both techniques.

METHODS

Eighteen fresh-frozen cadaveric hands were each tested under 3 different conditions: EPL in situ (baseline); EPL rerouted above the first extensor compartment (EC); and EPL rerouted through the first extensor compartment (IC). A controlled traction of 10 N was applied to the EPL under each condition. The range of thumb extension with respect to the fixed index finger was recorded utilizing infrared reflective markers and digital video capture.

RESULTS

The mean extension of the thumb with the EPL tendon in situ was 16.7°. The mean extension of the thumb was 22.0° with the EC transposition versus 25.0° with the IC technique. The measured thumb extension in both the EC and the IC techniques were found to be similar because both EPL transpositions yielded a significant difference in thumb extension when compared with baseline.

CONCLUSIONS

This biomechanical model demonstrates that radial transposition of the EPL tendon enhances extension of the thumb regardless of whether the tendon is routed through, or superficial to, the first extensor compartment.

CLINICAL RELEVANCE

A novel technique, the EC EPL transposition, offers a similar enhancement in measured thumb extension as the already-described IC EPL transposition.

Crush Injuries of the Hand

Crush injuries of the hand are a rare but devastating phenomenon, with historically poor outcomes. A compressive force, usually caused by a high-energy mechanism such as a motor vehicle or industrial accident, crushes and transiently increases the pressures within the hand. This force acts on the incompressible blood in the vasculature and leads to a dramatic rise in tissue pressures and damage to multiple tissue types, including bones, blood vessels, nerves, and soft tissues. A wide zone of injury results from a delayed inflammatory reaction involving the zone bordering the crushed cells, which may initially belie the severity of the injury. As such, these injuries go on to produce tremendous inflammation and swelling, potentially followed by compartment syndrome or other vascular damage, infection, neurological injury, and tissue necrosis. Crush injuries with minimal skin disruptions can be particularly challenging to accurately diagnose and manage. This paper provides a review of the initial evaluation of hand crush injuries as well as short- and long-term management strategies.