Duncan Thomas McGuire

The Effect of Lunate Morphology on the 3-Dimensional Kinematics of the Carpus

PURPOSE To assess carpal kinematics in various ranges of motion in 3 dimensions with respect to lunate morphology. METHODS Eight cadaveric wrists (4 type I lunates, 4 type II lunates) were mounted into a customized platform that allowed controlled motion with 6 degrees of freedom. The wrists were moved through flexion-extension (15°-15°) and radioulnar deviation (RUD; 20°-20°). The relative motion of the radius, carpus, and third metacarpal were recorded using optical motion capture methods. RESULTS Clear patterns of carpal motion were identified. Significantly greater motion occurred at the radiocarpal joint during flexion-extension of type I wrist than a type II wrist. The relative contributions of the midcarpal and radiocarpal articulations to movement of the wrist differed between the radial, the central, and the ulnar columns. During wrist flexion and extension, these contributions were determined by the lunate morphology, whereas during RUD, they were determined by the direction of wrist motion. The midcarpal articulations were relatively restricted during flexion and extension of a type II wrist. However, during RUD, the midcarpal joint of the central column became the dominant articulation. CONCLUSIONS This study describes the effect of lunate morphology on 3-dimensional carpal kinematics during wrist flexion and extension. Despite the limited size of the motion arcs tested, the results represent an advance on the current understanding of this topic. CLINICAL RELEVANCE Differences in carpal kinematics may explain the effect of lunate morphology on pathological changes within the carpus. Differences in carpal kinematics due to lunate morphology may have implications for the management of certain wrist conditions.

Endoscopic ulnar nerve release and transposition.

The most common site of ulnar nerve compression is within the cubital tunnel. Surgery has historically involved an open cubital tunnel release with or without transposition of the nerve. A comparative study has demonstrated that endoscopic decompression is as effective as open decompression and has the advantages of being less invasive, utilizing a smaller incision, producing less local symptoms, causing less vascular insult to the nerve, and resulting in faster recovery for the patient. Ulnar nerve transposition is indicated with symptomatic ulnar nerve instability or if the ulnar nerve is located in a “hostile bed” (eg, osteophytes, scarring, ganglions, etc.). Transposition has previously been performed as an open procedure. The authors describe a technique of endoscopic ulnar nerve release and transposition. Extra portals are used to allow retractors to be inserted, the medial intermuscular septum to be excised, cautery to be used, and a tape to control the position of the nerve. In our experience this minimally invasive technique provides good early outcomes. This report details the indications, contraindications, surgical technique, and rehabilitation of the endoscopic ulnar nerve release and transposition.

Anatomic foveal reconstruction of the triangular fibrocartilage complex with a tendon graft

An acute injury to the triangular fibrocartilage complex (TFCC) with avulsion of the foveal attachment can produce distal radioulnar joint (DRUJ) instability. The avulsed TFCC is translated distally so the footprint will be bathed in synovial fluid from the DRUJ and will become covered in synovitis. If the TFCC fails to heal to the footprint, then persistent instability can occur. The authors describe a surgical technique indicated for the treatment of persistent instability of the DRUJ due to foveal detachment of the TFCC. The procedure utilizes a loop of palmaris longus tendon graft passed through the ulnar aspect of the TFCC and into an osseous tunnel in the distal ulna to reconstruct the foveal attachment. This technique provides stability of the distal ulna to the radius and carpus. We recommend this procedure for chronic instability of the DRUJ due to TFCC avulsion, but recommend that suture repair remain the treatment of choice for acute instability. An arthroscopic assessment includes the trampoline test, hook test, and reverse hook test. DRUJ ballottement under arthroscopic vision details the direction of instability, the functional tear pattern, and unmasks concealed tears. If the reverse hook test demonstrates a functional instability between the TFCC and the radius, then a foveal reconstruction is contraindicated, and a reconstruction that stabilizes the radial and ulnar aspects of the TFCC is required. The foveal reconstruction technique has the advantage of providing a robust anatomically based reconstruction of the TFCC to the fovea, which stabilizes the DRUJ and the ulnocarpal sag.

A novel method to replicate the kinematics of the carpus using a six degree-of-freedom robot

Understanding the kinematics of the carpus is essential to the understanding and treatment of wrist pathologies. However, many of the previous techniques presented are limited by non-functional motion or the interpolation of points from static images at different postures. We present a method that has the capability of replicating the kinematics of the wrist during activities of daily living using a unique mechanical testing system. To quantify the kinematics of the carpal bones, we used bone pin-mounted markers and optical motion capture methods. In this paper, we present a hammering motion as an example of an activity of daily living. However, the method can be applied to a wide variety of movements. Our method showed good accuracy (1.0-2.6°) of in vivo movement reproduction in our ex vivo model. Most carpal motion during wrist flexion-extension occurs at the radiocarpal level while in ulnar deviation the motion is more equally shared between radiocarpal and midcarpal joints, and in radial deviation the motion happens mainly at the midcarpal joint. For all rotations, there was more rotation of the midcarpal row relative to the lunate than relative to the scaphoid or triquetrum. For the functional motion studied (hammering), there was more midcarpal motion in wrist extension compared to pure wrist extension while radioulnar deviation patterns were similar to those observed in pure wrist radioulnar deviation. Finally, it was found that for the amplitudes studied the amount of carpal rotations was proportional to global wrist rotations.

Olecranon extrabursal endoscopic bursectomy.

Olecranon bursitis is a common clinical problem. It is often managed conservatively because of the high rates of wound complications with the conventional open surgical technique. Conventional olecranon bursoscopy utilizes an arthroscope and an arthroscopic shaver, removing the bursa from inside-out. We describe an extrabursal endoscopic technique where the bursa is not entered but excised in its entirety under endoscopic vision. A satisfactory view is obtained with less morbidity than the open method, while still avoiding a wound over the sensitive point of the olecranon.

Reconstruction of Chronic Foveal TFCC Tears with an Autologous Tendon Graft

Background A triangular fibrocartilage complex (TFCC) injury can produce distal radioulnar joint (DRUJ) instability. If the foveal attachment is avulsed, it translates distally. The footprint is separated from its origin and will become covered in synovitis, preventing healing. The authors describe a surgical technique for the treatment of instability of the DRUJ due to chronic foveal detachment of the TFCC. Technique The procedure utilizes a loop of autologous palmaris longus tendon graft passed through the ulnar aspect of the TFCC and through an osseous tunnel in the distal ulna to reconstruct the fovel attachment. Patients and Methods We report on nine patients with a mean age of 42. Median follow-up was 13 months. Results The median pain scores measured were reduced from 8 to 3 postoperatively, and all had a stable DRUJ. Conclusions This technique provides stability of the distal ulna to the radius and carpus, with potential for biologic healing through osseous integration. It is a robust, anatomically based reconstruction of the TFCC to the fovea that stabilizes the DRUJ and the ulnar-carpal sag.

A Simplified Lateral Hinge Approach to the Proximal Interphalangeal Joint.

Proximal interphalangeal joint replacement is an effective treatment for painful arthritis affecting the joint. However, the complication rate is relatively high, with many of these complications related to soft-tissue imbalance or instability. Volar, dorsal, and lateral approaches have all been described with varying results. We describe a new simplified lateral hinge approach that splits the collateral ligament to provide adequate exposure of the joint. Following insertion of the prosthesis the collateral ligament is simply repaired, side-to-side, which stabilizes the joint. As the central slip, opposite collateral ligament, flexor and extensor tendons have not been violated, early active mobilization without splinting is possible, and the risk of instability, swan-neck, and boutonniere deformity are reduced. The indications, contraindications, surgical technique, and rehabilitation protocol are described.

Anatomy and Portals

Original cadaveric work by Burman in 1932 established that it was possible to introduce an arthroscope into the joint and visualise many aspects of it with relative ease, however it was Andrews and Carson’s paper in 1985, Morrey’s lectures in 1986 and further Poehling’s paper in 1989 that captured the attention of the orthopaedic community. A report of 473 cases, demonstrated that all major and cutaneous nerves around the elbow are at risk, with the ulnar nerve most likely to be involved. The risk increased in complex cases, such as in rheumatoid arthritis and capsular releases. A sound working knowledge of the neurovascular anatomy of the elbow and good technique is essential to performing elbow arthroscopy safely.

Distal radius attachments of the radiocarpal ligaments: an anatomical study

Background Understanding the anatomy of the ligaments of the distal radius aids in the surgical repair of ligamentous injuries and the prediction of intraarticular fracture patterns. Purposes (1) to measure the horizontal and vertical distances of the origins of the radiocarpal ligaments from the most ulnar corner of the sigmoid notch and the joint line, respectively; and (2) to express them as a percentile of the total width of the bony distal radius. Methods We dissected 8 cadaveric specimens and identified the dorsal radiocarpal, radioscaphocapitate, and the long and short radiolunate ligaments. Results The dorsal radiocarpal ligament attached from the 16th to the 52nd percentile of the radial width. The radioscaphocapitate ligament attached around the radial styloid from the 86th percentile volarly to the 87th percentile dorsally. The long radiolunate ligament attached from the 59th to the 85th percentile, and the short radiolunate ligament attached from the 14th to the 41st percentile. Discussion There was a positive correlation between the radial width and the horizontal distance of the ligaments from the sigmoid notch. These findings may aid individualized surgical repair or reconstruction adjusted to patient size and enable further standardized research on distal radial fractures and their relationship with radiocarpal ligaments.

Management of dislocations of the elbow in the athlete.

The elbow is the second most commonly dislocated large joint and occurs with more frequency in sports men and women than in the general population. Understanding the normal anatomy, the mechanism of injury and the pathoanatomy of the injury to the soft tissue restraints about the elbow are important for obtaining a good result. Most elbow dislocations are stable once reduced and may be treated conservatively. However, if the elbow remains unstable then surgical treatment of the medial and lateral collateral ligament complexes is recommended. Repair using tensionable anchors allows the surgeon to tension both medial and lateral sides sequentially in a controlled manner, and allows assessment of range and stability during the tensioning process. Once stability to the elbow has been restored, early active mobilization can be initiated, with the aim of returning to sport as soon as possible.