Biomedical subjects

Michael L Didonna

Publications and source records attributed to Michael L Didonna.

4 recordsLinked to original sources

PubMed2005

Complications and outcome of four-corner arthrodesis: circular plate fixation versus traditional techniques.

PURPOSE: To review the clinical and radiographic results of scaphoid excision and four-corner arthrodesis using a circular plate and screws compared with traditional fusion techniques (wires, staples, screws). METHODS: Fifty-eight patients with four-corner arthrodesis (plate fixation, n = 27; traditional fixation, n = 31) were evaluated for radiographic and clinical success using wrist radiographs and functional assays. Patients were subjectively surveyed using the standardized Disabilities of the Arm, Shoulder, and Hand questionnaire and classification scales for pain and satisfaction. Objective measurements included grip-strength and range-of-motion measurements. RESULTS: Radiographic analysis showed 26% nonunion with loose hardware in the plate group compared with 3% in the traditional group and 22% hardware impingement in the plate group compared with 3% in the traditional group. Clinical evaluation yielded a mean grip strength of 31 kg (70% of opposite side) for plate fixation and 33 kg (79% of opposite side) for traditional fixation. The mean flexion-extension arc was 48% and 50% of the opposite wrist for plate and traditional patients, respectively. The mean adjusted Disabilities of the Arm, Shoulder, and Hand questionnaire scores were 27 out of 100 for plate patients and 8 out of 100 for traditional patients. Pain classification scores showed that only 2 patients in the plate group were pain free whereas there were 8 patients in the traditional group who were pain free. Overall patient satisfaction was 60% for the plate group whereas the traditional patient group reported 100% satisfaction. CONCLUSIONS: The rate of major complications (nonunion or impingement) was much greater with circular plate fixation (48%) versus traditional fixation techniques (6%). With the plate procedure the grip strength and arc of motion decreased approximately 30% and 52%, respectively, compared with decreases of 21% and 50%, respectively, for traditional fusion methods. Additionally, subjective patient dissatisfaction was 40% in the plate group compared with 0% in the traditional group. We postulate that the increased complication and dissatisfaction rates associated with plate fixation may be attributable to possible biomechanical imperfections or increased technical demands with this fusion system.

Adolescent↗

PubMed2005

Proximal row carpectomy.

BACKGROUND: Proximal row carpectomy is an accepted motion-sparing surgical procedure for the treatment of degenerative conditions of the wrist. However, there is little information regarding the long-term clinical and radiographic results following this procedure. METHODS: Twenty-two wrists in twenty-one patients underwent proximal row carpectomy for the treatment of degenerative arthritis between 1980 and 1992. Objective and subjective function was assessed after a minimum duration of follow-up of ten years (average, fourteen years). RESULTS: There were four failures (18%) requiring fusion at an average of seven years. All four failures occurred in patients who were thirty-five years of age or less at the time of the proximal row carpectomy (p = 0.03). The wrists that did not fail had an average flexion-extension arc of 72 degrees , associated with an average grip strength of 91% of that on the contralateral side. The patients were very satisfied with fourteen of the eighteen wrists that did not fail and were satisfied with the remaining four. The patients rated nine wrists as not painful, four as mildly painful, five as moderately painful, and none as severely painful. The average Disabilities of the Arm, Shoulder and Hand score was 9 points. Radiographs revealed no loss of the radiocapitate space in three of the seventeen wrists for which radiographs were made, reduced space in seven, and complete loss of the space in seven. With the numbers available, there was no significant association between loss of joint space seen on radiographs and subjective and objective function. CONCLUSIONS: At the time of long-term followup, all patients older than thirty-five years of age at the time of a proximal row carpectomy had maintained a satisfactory range of motion, grip strength, and pain relief and were satisfied with the result. Caution should be exercised in performing the procedure in patients younger than thirty-five years of age. Although degeneration of the radiocapitate joint was seen radiographically in fourteen of the seventeen wrists, it did not preclude a successful clinical result.

Adult↗

PubMed2003

Partial olecranon excision: the relationship between triceps insertion site and extension strength of the elbow.

PURPOSE: Partial excision with triceps reattachment is an accepted method for treating comminuted fractures of the olecranon. The currently recommended site for reattachment is along the articular margin of the remaining olecranon process. With computer models suggesting that this may lead to weakness of elbow extension, this study was performed to evaluate different sites for triceps reattachment with respect to extension strength of the elbow. METHOD: Ten fresh frozen human cadavers were potted and the elbow placed in varying degrees of flexion (45 degrees, 90 degrees, and 135 degrees ). Incremental loads were applied to the triceps mechanism and the force generated was recorded using an Instron materials testing machine (Instron Corp., Canton, MA). A 50% olecranon excision was then performed, simulating a comminuted olecranon fracture. The triceps tendon was attached either anteriorly along the articular margin or posteriorly along the cortical margin. All specimens were tested at both insertion sites in random order. RESULTS: A significant decrease in extension strength was observed between intact specimens and anterior attachment of the triceps tendon at all angles of elbow flexion. A decrease was only observed with posterior reattachment at 90 degrees. Posterior reattachment provided greater extensor strength than anterior attachment, with greatest differences seen at increasing positions of elbow extension. CONCLUSIONS: Although anterior reattachment of the triceps tendon after partial excision of the olecranon is currently recommended by some, this results in diminished strength of the triceps mechanism. A greater mechanical advantage with increased strength is provided by a more posterior reattachment using the technique described. These differences are greatest at increasing positions of elbow extension where triceps strength is more functionally important.

Biomechanical Phenomena↗

PubMed2002

Implant design affects markers of bone resorption and formation in total hip replacement.

Concentrations of the bone resorption markers pyridinoline and deoxypyridinoline and the bone formation marker osteocalcin were measured in 24-h urine collections from 30 subjects who underwent unilateral total hip replacements for monoarticular symptomatic osteoarthrosis and 10 controls. The patient groups were divided based on the femoral implant type (cemented cobalt alloy stem, cementless porous coated cobalt alloy stem, and cementless porous coated titanium alloy stem). Urine collections were performed before surgery and then at 3, 6, 12, 24, and 36 months. There were significant changes over time in the three patient groups for pyridinoline, deoxypyridinoline, and the ratio of osteocalcin to deoxypyridinoline (p < or = 0.01), but the control group values did not change over time. The resorption markers tended to peak at 3 months and the osteocalcin to deoxypyridinoline ratio was more variable, having depressed values in the cementless cobalt alloy group and elevated values in the other two groups compared with baseline. The cementless cobalt alloy group had higher resorption marker levels than the cemented cobalt alloy group at 6, 12, 24, and 36 months and higher levels than the cementless titanium alloy group at all postoperative times (p < 0.05). The osteocalcin to deoxypyridinoline ratio was lower in the cementless cobalt alloy group than in the cemented cobalt alloy group at 3, 6, and 24 months and the cementless titanium alloy group at 6, 12, and 24 months (p < 0.05). For the cemented cobalt chrome group, the baseline-normalized resorption marker values at 3 months and 6 months were correlated with the severity of radiographically assessed bone loss at 36 months (0.749 < r < 0.840; p < 0.05). For the cementless titanium alloy group, baseline-normalized osteocalcin/ deoxypyridinoline ratios at 3 months and 6 months were related inversely to radiographic bone loss at 36 months (0.687 < r < 0.749; p < 0.05). Thus, body fluid markers of bone metabolism change after total hip replacement. In addition, the changes in the marker concentrations were sensitive to implant design and were correlated with subsequent stress-shielding-induced bone loss.

Adult↗