Biomedical subjects
Publications and source records attributed to T R Light.
Pediatric carpal injury is unusual. Because of its rarity and imaging difficulties, the diagnosis is often delayed. Open reduction is advocated for displaced injuries. Pin fixation provides temporary stabilization of displaced injuries without permanently compromising joint motion. In older children, intercarpal fusion may be elected for treatment of intercarpal instability.
A case of a displaced coronal fracture of the hamate body with a 1-month delay in diagnosis is presented with a review of the literature regarding hamate-body fractures. Mechanism, diagnosis, and treatment options are discussed. This diagnosis should be suspected on initial review of plain radiographs, which must include an oblique view in any patient presenting with pain after blunt trauma to the hand. Open reduction with internal fixation is reserved for unstable, displaced fractures. Care should be taken to preserve the vascular supply to the displaced fragment, and a two-incision technique is recommended to minimize risk to the motor branch of the ulnar nerve.
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Osteoid osteomas, relatively rare lesions in the upper extremity, can be a persistent source of hand or wrist pain. Patients under age 40 who have otherwise unexplained pain should be evaluated. Relief of pain with oral nonsteroidal anti-inflammatory drugs should suggest the possibility of osteoid osteoma. Examination may demonstrate localized swelling or joint effusion. Radiographs should be examined for sclerosis in the region of pain. If radiographs are nondiagnostic, a bone scan should be obtained. If the nidus cannot be clearly visualized by radiography and bone scan, a CT scan should be obtained. If the location of the nidus makes excision difficult without removal of a large block of bone, localization with a CT-guided needle or by radioisotope labeling will help to assure removal of the nidus.
Metacarpals, metatarsals, and phalanges were studied to assess the developmental morphology of "secondary" ossification in the "nonepiphyseal" ends of these bones as well as the formation of the pseudoepiphysis as an epiphyseal ossification variant. Both direct ossification extension from the metaphysis into the epiphysis and pseudoepiphysis formation preceded, and continued to be more mature than, formation and expansion of the "classic" epiphyseal (secondary) ossification center at the opposite end of each specific bone. Direct metaphyseal to epiphyseal ossification usually started centrally and expanded hemispherically, replacing both physeal and epiphyseal cartilage simultaneously. In contrast, when remnants of "physis" were retained, while juxtaposed epiphyseal cartilage was replaced, a pseudoepiphysis formed. There were three basic patterns of pseudoepiphysis formation. First, a central osseous bridge extended from the metaphysis across the "physis" into the epiphysis and subsequently expanded to create a mushroom-like osseous structure. In the second pattern a peripheral osseous bridge formed, creating either an osseous ring or an eccentric bridge between the metaphysis and the epiphysis. In the third pattern, multiple bridging occurred. In each situation the associated remnant "physis" lacked typical cell columns and was incapable of significantly contributing to the postnatal longitudinal growth of the involved bone. Pseudoepiphyses were well formed by 4-5 years and coalesced with the rest of the bone months of years before skeletal maturation was attained at the opposite epiphyseal end, which ossified in the typical pattern (i.e., formation of a secondary center de novo completely within the cartilaginous epiphysis). This process may also affect the development and appearance of ossification within the longitudinal epiphyseal bracket ("delta phalanx").
This study investigated the relative roles of the interosseous membrane (IOM) and triangular fibrocartilage complex (TFCC) in the transmission of force from the hand to the humerus. Our findings suggest a spectrum of forearm destabilizing injuries. The intact radius abutting the capitellum provides the primary restraint to proximal migration of the radius. After radial head excision, up to 7 mm of proximal radial migration can occur under axial compression. If the TFCC or the IOM alone is disrupted, little alteration in load or displacement is evident. When both the midportion of the IOM and TFCC are incompetent, however, further proximal radial migration occurs, the radial stump abuts the humerus, and load is shifted back to the radial column. These data suggest that the central portion of the IOM is the crucial structural subdivision within the IOM acting as a restraint to proximal radial migration. The TFCC also resists proximal radial migration and participates in load transfer. We propose that clinical migration of the radius under an axial load greater than 7 mm implies disruption of both the midportion of the IOM and TFCC.
Nineteen consecutive patients underwent traumatic upper limb amputation for nonreconstructible or replantible upper limb injury at a Level I trauma center over a 9-year-period. Eleven amputations were at the transradial level, five were transhumeral, and three were shoulder disarticulation. Eighteen patients underwent prosthetic limb fitting. Fifteen of the 18 initially underwent preparatory prosthetic limb fitting within 30 days following amputation with a body-powered, cable-driven prosthesis. Seventeen of the 18 achieved sufficient proficiency with their prostheses to allow them to return to work. Of these, 15 maintained daily functional prosthetic use of at least 8 hours daily at a followup examination of 12 to 110 months. Use of prosthetic limb following traumatic upper limb amputation carries a high probability for functional rehabilitation if limb fitting and prosthetic training are instituted as soon as the residual limb can tolerate the prosthetic socket as opposed to waiting for the residual limb to "mature".
Displaced intra-articular fractures of the metacarpal head and of the proximal articular surface of the proximal phalanx often require open reduction and internal fixation, particularly if an articular step off is present. If secure internal fixation can be achieved, early motion may be instituted. Diagnosis may be facilitated by special views and tomography. Secondary reconstructive procedures may include tenolysis, osteotomy, arthroplasty, or tissue transfer from the foot.
Cubital tunnel syndrome is the most common entrapment of the ulnar nerve. Complications in the treatment of cubital tunnel syndrome may be caused by errors in diagnosis, errors in conservative management, and errors of surgical treatment. This article discusses each cause of complications separately, with a division in errors of surgical treatment into complications from decompression of the ulnar nerve, medial epicondylectomy, anterior transposition of the ulnar nerve, intramuscular transposition of the ulnar nerve, subcutaneous transposition of the ulnar nerve, submuscular transposition of the ulnar nerve, and failed surgical treatment.
The mechanical strength of the human radius and ulna depends on their geometrical and material properties. This study quantifies the cortical bone cross-sectional properties of the adult radius and ulna (cross-sectional area, thickness, centroids, area moments of inertia and section moduli) using computerized tomographic (CT) scanning coupled with image processing along the lengths of eight human cadaveric forearms. Bone mineral mass and apparent ash density were also quantified at serial locations. Sites of significant variation of selected geometric and mineral properties along the length of each forearm bone were determined. Our results show that interpolation of CT measurements made at 10 and 30% of the radial length in the radius and 30 and 90% of the radial length in the ulna can provide approximate geometric values over the 10-90% region. This information can be used to develop a protocol using the fewest sites to clinically assess changes in forearm bone geometry. Regression analyses did not show significant linear relationships between geometric properties and apparent cortical ash density. Thus, CT derived geometric properties are not helpful in estimating the extent of changes in bone density. Area moment of inertia results suggest that the junction of the middle and distal third of the radius, and the ulnar shaft region may have increased vulnerability to fractures. The former is likely due to the change in moment of inertia values, whereas the latter is due to the relatively small magnitude of cross-sectional moments along the ulnar shaft as compared to the proximal or distal ends. This is consistent with fracture patterns observed clinically when a single forearm bone is fractured: Galeazzi fracture of the radius and nightstick fracture of the ulna.
A 24-year-old woman sustained a closed head injury. She regained consciousness over a 2-month period but heterotopic ossification developed around both elbows and the proximal interphalangeal joints of her left ring and long fingers. The new bone was allowed to mature and was subsequently resected from both elbows and the fingers with substantial improvement in function. There is no clear explanation for the formation of such heterotopic bone.
Preaxial polydactyly is the result of aberrant bifurcation of the embryonic preaxial anlage. Effective reconstruction of thumb duplication requires careful evaluation of all components. Skin, nail, bone, ligament, and musculoskeletal elements must be combined to reconstruct an optimal digit.
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This case report describes the clinical course of a boy 12 years and 11 months old with the skeletal maturity of an 11.5-year-old, with a distal radial fracture that completely remodeled with 36 degrees of radial and 10 degrees of dorsal angulation. As this case demonstrates, the distal forearm may correct angulation in more than one plane. The remodeling capacity depends on the skeletal maturity of the patient, the proximity of the fracture site to the growth plate, the extent of angulation, and the relationship between the plane of angulation and motion of neighboring joints.
When accidents occur, the hand is the part of the body most often thrust out to lessen the consequences, resulting in a wide array of combinations of soft-tissue and chondro-osseous injuries. Pediatric wrist and hand skeletal injuries discussed in this article include growth mechanism injury, fractures and dislocations, nailbed injuries, fingertip injuries, burns, and frostbite.
Previous experimental studies of partial flexor tendon lacerations have used tendons cut by hand with magnification and a scalpel. When we biomechanically tested chicken flexor tendons lacerated by hand through 75% of their cross-sectional area, the tensile strength of the residual tendons varied substantially among specimens from different chickens as well as between digit matched pairs of tendons from the same animal. A device was designed that uses standard scalpel blades to create a uniform tendon laceration by leaving a constant area of tendon intact regardless of original tendon size or shape. With the instrument we have called the "tenotome," a second group of chicken flexor tendons were lacerated through 75% of their cross-sectional area. Biomechanical testing of the tendons cut with the tenotome showed significantly less variation when compared with the tendons cut by hand. Use of the tenotome permits the establishment of a more uniform model for partial flexor tendon injuries, and potentially decreases the number of specimens needed to demonstrate statistical significance.
Retrospective analysis of 48 medial epicondylectomy procedures in 46 patients demonstrated that symptomatic and objective improvement was usual. Most patients experienced improvement of symptoms (98%) and moving two-point discrimination (87%), and many demonstrated improved motor strength (54%). By use of the McGowan scheme for grading ulnar neuropathy, 92% of the patients with grade I neuropathy had a return to normal function. Subdividing patients with grade II neuropathy into grade IIA and IIB on the basis of the extent of motor compromise was useful in predicting postoperative outcome. Forty-five percent of the patients with grade IIA neuropathy had a return to normal ulnar nerve function and only 11% (one patient) in the IIB group had a full recovery. In the group with grade III neuropathy, one patient had improvement to grade II level and the other five remained grade III. No patient in this study demonstrated deterioration of his McGown grade. Medial epicondylectomy is a safe and predictable procedure for the treatment of symptomatic cubital tunnel syndrome.
The relative importance of the three major periscaphoid ligament complexes in maintaining the normal radiocarpal articulation was assessed. Pressure-sensitive film recorded the changes in radioscaphoid and radiolunate articular contact that occurred with sequential ligament sectioning in 12 cadaver wrists. Alterations in the radiocarpal articular contact as a result of ligament disruption are evident in the absence of the recognizable static x-ray changes of carpal instability. The scapholunate interosseous ligament is essential in preventing scapholunate diastasis and dorsoradial subluxation of the proximal scaphoid. Rotatory subluxation of the scaphoid occurs when disruption of the scapholunate interosseous ligament is coupled with disruption of either the palmar intracapsular radiocarpal ligaments or the scaphotrapezial ligament complex. These data help explain the development of degenerative arthritis caused by carpal ligamentous instability.