Radiologic Guide to Surgical Treatment of Kienbock's Disease.

Kienbock's disease, or avascular necrosis of the lunate, is a progressive disease ultimately resulting in end-stage arthrosis of the wrist. Various surgical treatments are available for different Lichtman stages of disease. We review the surgical options and indications, expected radiologic post-operative appearance, as well as detail potential surgical complications, as they relate to Kienbock's disease.

Diagnosis and Treatment of Work-Related Ulnar Neuropathy at the Elbow.

Ulnar neuropathy at the elbow (UNE) is the second most common entrapment neuropathy after carpal tunnel syndrome and occurs most commonly at the elbow due to mechanical forces that produce traction or ischemia to the nerve. The primary symptom associated with UNE is diminished sensation or dysesthesias in the fourth or fifth digits, often coupled with pain in the proximal medial aspect of the elbow. Treatment may be conservative or surgical, but optimal management remains controversial. Surgery should include exploration of the ulnar nerve throughout its course around the elbow and release of all compressive structures.

Functional Outcomes Following Bridge Plate Fixation for Distal Radius Fractures.

PURPOSE: To determine the functional outcomes of patients treated with dorsal spanning distraction bridge plate fixation for distal radius fractures. METHODS: All adult patients at our institution who underwent treatment of a unilateral distal radius fracture using a dorsal bridge plate from 2008 to 2012 were identified retrospectively. Patients were enrolled in clinical follow-up to assess function. Wrist range of motion, grip strength, and extension torque were measured systematically and compared with the contralateral, uninjured wrist. Patients also completed Quick-Disabilities of the Arm, Shoulder, and Hand and Patient-Rated Wrist Evaluation outcomes questionnaires. RESULTS: Eighteen of 100 eligible patients, with a minimum of 1 year from the time of implant removal, were available for follow-up (mean, 2.7 y). All fracture patterns were comminuted and intra-articular (AO 23.C3). There were significant decreases in wrist flexion (43° vs 58°), extension (46° vs 56°), and ulnar deviation (23° vs 29°) compared with the contralateral uninjured wrist. Grip strength was 86% and extension torque was 78% of the contralateral wrist. Comparison of dominant and nondominant wrist injuries identified nearly complete recovery of grip (95%) and extension (96%) strength of dominant-sided wrist injuries, compared with grip (79%) and extension (65%) strength in those with an injured nondominant wrist. Mean Quick-Disabilities of the Arm, Shoulder, and Hand and Patient-Rated Wrist Evaluation scores were 16 and 14, respectively. There were 2 cases of postoperative surgical site pain and no cases of infection, tendonitis, or tendon rupture. CONCLUSIONS: Distraction bridge plate fixation for distal radius fractures is safe with minimal complications. Functional outcomes are similar to those published for other treatment methods. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Modeling Implantable Passive Mechanisms for Modifying the Transmission of Forces and Movements Between Muscle and Tendons.

This paper explores the development of biomechanical models for evaluating a new class of passive mechanical implants for orthopedic surgery. The proposed implants take the form of passive engineered mechanisms, and will be used to improve the functional attachment of muscles to tendons and bone by modifying the transmission of forces and movement inside the body. Specifically, we present how two types of implantable mechanisms may be modeled in the open-source biomechanical software OpenSim. The first implant, which is proposed for hand tendon-transfer surgery, differentially distributes the forces and movement from one muscle across multiple tendons. The second implant, which is proposed for knee-replacement surgery, scales up the forces applied to the knee joint by the quadriceps muscle. This paper's key innovation is that such mechanisms have never been considered before in biomechanical simulation modeling and in surgery. When compared with joint function enabled by the current surgical practice of using sutures to make the attachment, biomechanical simulations show that the surgery with 1) the differential mechanism (tendon network) implant improves the fingers' ability to passively adapt to an object's shape significantly during grasping tasks (2.74× as measured by the extent of finger flexion) for the same muscle force, and 2) the force-scaling implant increases knee-joint torque by 84% for the same muscle force. The critical significance of this study is to provide a methodology for the design and inclusion of the implants into biomechanical models and validating the improvement in joint function they enable when compared with current surgical practice.

Implanted passive engineering mechanism improves hand function after tendon transfer surgery: a cadaver-based study.

PURPOSE: The purpose of this study was to investigate if a new tendon transfer surgical procedure that uses an implanted passive engineering mechanism for attaching multiple tendons to a single donor muscle in place of directly suturing the tendons to the muscle improves hand function in physical interaction tasks such as grasping. METHODS: The tendon transfer surgery for high median ulnar palsy was used as an exemplar, where all four flexor digitorum profundus (FDP) tendons are directly sutured to the extensor carpi radialis longus (ECRL) muscle to restore flexion. The new procedure used a passive hierarchical artificial pulley system to connect the muscle to the tendons. Both the suture-based and pulley-based procedures were conducted on N = 6 cadaver hands. The fingers' ability to close around four objects when the ECRL tendon was pulled was tested. Post-surgery hand function was evaluated based on the actuation force required to create a grasp and the slip between the fingers and the object after the grasp was created. RESULTS: When compared with the suture-based procedure, the pulley-based procedure (i) reduced the actuation force required to close all four fingers around the object by 45 % and (ii) improved the fingers' individual adaptation to the object's shape during the grasping process and reduced slip by 52 % after object contact (2.99° ± 0.28° versus 6.22° ± 0.66°). CONCLUSIONS: The cadaver study showed that the implanted engineering mechanism for attaching multiple tendons to one muscle significantly improved hand function in grasping tasks when compared with the current procedure.

Complications associated with distraction plate fixation of wrist fractures.

This article discusses the major and minor complications of distal plating in the light of a cohort study carried out by the authors, who reviewed all patients undergoing bridge distraction plate fixation of distal radius fractures by three surgeons in a single level I trauma center. The article discusses the effectiveness and the complication rates associated with the technique.