Three-dimensional analysis of the palmar plate and collateral ligaments at the proximal interphalangeal joint.

The purpose of this study was to analyze the palmar plate complex at the proximal interphalangeal joint using a three-dimensional (3D) technique, which makes it easier to understand the dimensions of structures and their relationship to the adjacent components. This method allows individual elements to be removed virtually, facilitating clearer observation of each component. Sixteen cadaveric specimens were dissected and reconstructed in a 3D virtual environment. The palmar plate is made up of a distal, fibrous portion and a proximal, membranous portion, which anchors distally on the base of the middle phalanx and is continuous with the bilateral check-rein ligaments proximally. The accessory collateral ligaments and the A3 pulley suspend the palmar plate laterally.

Non-invasive, non-radiological quantificationof anteroposterior knee joint ligamentous laxity: A study in cadavers.

OBJECTIVES: We performed in vitro validation of a non-invasive skin-mounted system that could allow quantification of anteroposterior (AP) laxity in the outpatient setting. METHODS: A total of 12 cadaveric lower limbs were tested with a commercial image-free navigation system using trackers secured by bone screws. We then tested a non-invasive fabric-strap system. The lower limb was secured at 10° intervals from 0° to 60° of knee flexion and 100 N of force was applied perpendicular to the tibia. Acceptable coefficient of repeatability (CR) and limits of agreement (LOA) of 3 mm were set based on diagnostic criteria for anterior cruciate ligament (ACL) insufficiency. RESULTS: Reliability and precision within the individual invasive and non-invasive systems was acceptable throughout the range of flexion tested (intra-class correlation coefficient 0.88, CR 1.6 mm). Agreement between the two systems was acceptable measuring AP laxity between full extension and 40° knee flexion (LOA 2.9 mm). Beyond 40° of flexion, agreement between the systems was unacceptable (LOA > 3 mm). CONCLUSIONS: These results indicate that from full knee extension to 40° flexion, non-invasive navigation-based quantification of AP tibial translation is as accurate as the standard validated commercial system, particularly in the clinically and functionally important range of 20° to 30° knee flexion. This could be useful in diagnosis and post-operative evaluation of ACL pathology. Cite this article: Bone Joint Res 2013;2:233-7.

An association between lunate morphology and scaphoid-trapezium-trapezoid arthritis.

The purpose of this study was to determine if an association exists between scaphoid-trapezium-trapezoid arthritis and lunate morphology. Plain neutral posteroanterior radiographs were evaluated for 48 patients with STT arthritis and 96 patients from a control group. Lunate type was determined using capitate-triquetrum (C-T) distance. A type I lunate was defined as a C-T distance < or =2 mm. A type II lunate was defined as a C-T distance > or =4 mm. Lunate type was recorded and compared between those with STT arthritis and a control group. The groups were similar with regard to age, gender and handedness. Type II lunates were found in 83% of cases with STT arthritis and in 64% of controls. STT OA was associated with type II lunate wrists (P = 0.02; OR = 0.35; CI: 0.15-0.82). We postulate that variations in scaphoid motion secondary to lunate morphology may contribute to the development of STT OA.

Effect of scaphoid and triquetrum excision after limited stabilisation on cadaver wrist movement.

This study assessed the effect of excision of the scaphoid and triquetrum on the range of motion of the embalmed cadaver wrist joint after midcarpal stabilisation. The range of motion was measured in 12 cadaver wrists before and after stabilisation of the joints between the lunate, capitate, triquetrum and hamate. This was measured again following resection of the scaphoid and then the triquetrum. Scaphoid excision after four-corner stabilisation increased the radioulnar (RU) arc by 12 degrees and the flexion-extension (F-E) arc by 10 degrees. Subsequent excision of the triquetrum, to produce a three-corner stabilisation, further increased the RU arc by 7 degrees and the F-E arc by 6 degrees. Three-corner stabilisation with excision of scaphoid and triquetrum improved wrist motion in embalmed cadavers.

Distal biceps tendon anatomy: a cadaveric study.

BACKGROUND: The anatomy of the distal biceps tendon and aponeurosis has not been studied in detail. METHODS: Seventeen cadaver elbows were dissected with loupe magnification to identify the details of the distal biceps tendon and the lacertus fibrosus. RESULTS: In ten of the seventeen specimens, the distal biceps tendon was in two distinct parts, each a continuation of the long and short heads of the muscle. The remaining seven specimens showed interdigitation of the muscle distally. The tendon continued from each muscle belly. The short head inserted distal to the radial tuberosity and was positioned to be a more powerful flexor of the elbow, while the tendon of the long head inserted on the tuberosity further from the axis of rotation of the forearm and was positioned to be a stronger supinator. The bicipital aponeurosis consisted of three layers and completely encircled the ulnar forearm flexor muscles. The aponeurosis may be important in stabilizing the tendons distally. CONCLUSIONS: The double tendon insertion may allow an element of independent function of each portion of the biceps, and, during repair of an avulsion, the surgeon should ensure correct orientation of both tendon components.

A case of an anomalous pectoralis major muscle.

We present a case of a right sided accessory head of the pectoralis major muscle located inferior to its abdominal head. This variation was found during a routine anatomy dissection at the American University of the Caribbean School of Medicine. The muscle fibres of the accessory head of the pectoralis major muscle arose from those of the serratus anterior muscle and travelled superolaterally towards the axilla. The accessory muscle terminated by fusing with the tendinous fibres of the pectoralis major muscle as they underwent their normal anatomical rotation before insertion upon the lateral lip of the bicipital groove of the humerus. Although variations in the pectoral muscles are not uncommon, this case appears to be unique in the literature. The possible clinical implications are discussed.