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Biomedical subjects

David R Pichora

Publications and source records attributed to David R Pichora.

10 recordsLinked to original sources
PubMed2006

Fractional flexor tendon lengthening for advanced metacarpophalangeal flexion contracture in rheumatoid hands.

This technical report discusses a subgroup of rheumatoid patients who have minimal ulnar drift but a severe fixed metacarpophalangeal joint flexion contracture for whom conventional metacarpophalangeal joint arthroplasty alone was insufficient to correct the deformity. We describe a surgical technique to deal with this clinical problem that uses fractional flexor tendon lengthening in the forearm to correct the severe flexion deformity at the metacarpophalangeal joint.

Aged↗
PubMed2006

The rheumatoid wrist.

Wrist involvement is common in patients with rheumatoid arthritis. Individual patient assessment is important in determining functional deficits and treatment goals. Patients with persistent disease despite aggressive medical management are candidates for surgery. Soft-tissue procedures offer good symptomatic relief and functional improvement in the short term. Extensor and flexor tendons may rupture because of synovial infiltration and bony irritation. When rupture occurs, direct repair usually is not possible. However, when joints that are motored by the ruptured tendon are still functional, tendon transfer or grafting may be considered. Because of the progressive nature of the disease, dislocation and end-stage arthritis often require stabilization with bony procedures. The distal radioulnar joint is usually affected first and is commonly treated with either the Darrach or the Sauvé-Kapandji procedure. Partial wrist fusion offers a compromise between achieving stability of the affected radiocarpal joint and maintaining motion at the midcarpal joint. For pancarpal arthritis, total wrist fusion offers reliable pain relief at the cost of motion. Total wrist arthroplasty is an alternative that preserves motion; however, the outcomes of total wrist replacement are still being evaluated.

Arthritis, Rheumatoid↗
PubMed2004

Early failures with a spheric interposition arthroplasty of the thumb basal joint.

PURPOSE: The purpose of this study is to report the early results with the Orthosphere (Wright Medical Technology Inc, Arlington, TN) spheric interpositional arthroplasty. METHODS: Six women and 1 man had Orthosphere arthroplasty between 2000 and 2001. The mean age at the time of surgery was 52 years (range, 24-73 years) and the mean duration of clinical and radiographic follow-up evaluation was 33 months (range, 29-44 months). RESULTS: Six of 7 Orthosphere implants subsided into the trapezium resulting in pain, weakness, and stiffness. There was 1 implant dislocation. Five patients have had revision surgery to trapezial excision ligament reconstruction and tendon interposition arthroplasty. Of the remaining 2 patients 1 is contemplating presently revision surgery and the other is experiencing mild residual pain. No patients were satisfied completely with their Orthosphere results. CONCLUSIONS: In our experience the early outcome of the Orthosphere interpositional arthroplasty has been unacceptable. We no longer use the device at our institutions.

Adult↗
PubMed2004

Mechanical properties of the scapholunate ligament correlate with bone mineral density measurements of the hand.

The mechanical properties of the scapholunate ligament have been previously examined in small sample sizes, with ultimate load and occasionally stiffness reported. The present study examined 16 scapholunate ligaments in uniaxial extension at two rates and determined stiffness, ultimate load, and stress relaxation properties. Mean stiffness values of 66.4+/-28.6 N/mm at an elongation rate of 50 mm/min and 94.5+/-44.4 N/mm at an elongation rate of 100 mm/min were found. Relaxation behavior, determined by the percent load remaining after 100 s, was found to be 68.1+/-12%. Mean ligament ultimate loads were 357+/-110 N (n = 8). In eight specimens, failure occurred in bone. Positive correlations were observed between bone mineral density of the hand and ligament stiffness, ligament ultimate load, and bone ultimate load. No correlation was observed between bone mineral density and ligament load relaxation behavior. The results provide a comprehensive understanding of scapholunate ligament biomechanics and demonstrate a relationship between bone and ligament properties.

Absorptiometry, Photon↗
PubMed2003

Computer-assisted distal radius osteotomy.

PURPOSE: To establish the accuracy, precision, and clinical feasibility of a novel technique of computer-assisted distal radius osteotomy for the correction of symptomatic distal radius malunion. METHODS: Six patients underwent a computer-assisted distal radius osteotomy and were followed-up for an average of 25 months. Objective radiographic measurements and functional outcomes, as measured by clinical examination including grip strength and range of motion, and Disability of the Arm, Shoulder and Hand (DASH) questionnaires, were used. RESULTS: The mean radiographic parameters included an increase of radial inclination to 21 degrees from 12 degrees (normal, 23 degrees ). Dorsal and volar tilt (malunion) were corrected to 9 degrees from -30 degrees and 21 degrees, respectively (normal, 10 degrees ). Ulnar variance was corrected to 1.9 mm from 7.5 mm (normal, +1.5 mm). Normal is defined as the average of the contralateral limb radiographs. The mean clinical outcome measures at an average of 25 months included a DASH global score of 14, a DASH individual item average score of 1.6, and an average affected side grip strength of 79% when compared with the unaffected side. CONCLUSIONS: The results of the computer-assisted technique were comparable with published results of traditional non-computer-assisted opening wedge osteotomy techniques. This technique allows a surgeon to accurately and precisely recognize and correct 3-dimensional deformities of the distal radius including axial malalignment (supination). The technique has the added benefit of reducing radiation exposure to the patient and surgical team because fluoroscopy is not used during the procedure. Additional benefits of the computer-assisted technique include the ability to perform multiple surgical simulations to optimize the alignment plan, and it serves as an excellent teaching tool for less-experienced surgeons.

Adult↗
PubMed2003

Development of a three-dimensional finite element model for carpal load transmission in a static neutral posture.

A three-dimensional developmental finite element model has been created to analyze load transmission pathways in the constrained carpus during static compressive loading. The bone geometry was extracted from an in vivo computed tomography scan using a combination of commercial and proprietary software. The complete geometry, including bone, cartilage, and ligament tissues, was compiled using a commercial finite element program. This model extends the state of biomechanical modeling by being the first to incorporate all eight carpal bones of the wrist and the related soft tissues in three dimensions. The model results indicate that cartilage material modulus and unconstrained carpal rotation have substantial impacts on the articular contact patterns and pressures.

Algorithms↗
PubMed2002

The sensitivity of carpal bone indices to rotational malpositioning.

We investigated the dependence of 20 radiographic carpal measurements (carpal indices) on rotational positioning errors in posteroanterior and lateral radiographs. The measurements were made from "true perspective" digitally reconstructed radiographs created from computed tomography data. Most posteroanterior indices were not affected by rotation. Carpal height, carpal height ratio, revised carpal height ratio, capitate-radius distance, and carpal ulnar translocation were particularly robust. Lateral-view indices involving the scaphoid were the most sensitive to simulated malpositioning: radioscaphoid, scapholunate, and scaphocapitate angles were reduced from 58 degrees, 48 degrees, and 56 degrees at true lateral to 30 degrees, 24 degrees, and 34 degrees, respectively, at 20 degrees external rotation. Observers were unable to estimate the degree of malpositioning accurately in either view. Our results support use of the "scaphopisocapitate" criterion for assessing correct positioning in lateral plain radiographs.

Adult↗
PubMedDate not supplied

Evaluation of interventions for rotator cuff pathology: a systematic review.

A systematic review of published evidence was conducted investigating surgical and conservative management of rotator cuff disease. Medical databases searched included Medline, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Physiotherapy Evidence Database (PEDro), and the Cochrane Collaboration library. Two independent reviewers evaluated each article for inclusion. Established criteria were used to assess the methodologic quality of articles examining outcomes of treatment interventions for rotator cuff disease. Due to the low methodologic quality of the studies that are currently available in this area, there is insufficient evidence to strongly support or refute the effectiveness of any available treatment intervention for rotator cuff pathology. The best available evidence supports open and primary surgery over arthroscopic debridement and revision surgery; and in the area of conservative management, electrotherapy, steroid use, exercise therapy, and acupuncture. There is a clear need for more methodologically sound studies to achieve strong evidence on which treatment practices can be based.

Acupuncture Therapy↗
PubMedDate not supplied

A system for ultrasound-guided computer-assisted orthopaedic surgery.

Current computer-assisted orthopedic surgery (CAOS) systems typically use preoperative computed tomography (CT) and intraoperative fluoroscopy as their imaging modalities. Because these imaging tools use X-rays, both patients and surgeons are exposed to ionizing radiation that may cause long-term health damage. To register the patient with the preoperative surgical plan, these techniques require tracking of the targeted anatomy by invasively mounting a tracking device on the patient, which results in extra pain and may prolong recovery time. The mounting procedure also leads to a major difficulty of using these approaches to track small bones or mobile fractures. Furthermore, it is practically impossible to mount a heavy tracking device on a small bone, which thus restricts the use of CAOS techniques. This article presents a novel CAOS method that employs 2D ultrasound (US) as the imaging modality. Medical US is non-ionizing and real-time, and our proposed method does not require any invasive mounting procedures. Experiments have shown that the proposed registration technique has sub-millimetric accuracy in localizing the best match between the intraoperative and preoperative images, demonstrating great potential for orthopedic applications. This method has some significant advantages over previously reported US-guided CAOS techniques: it requires no segmentation and employs only a few US images to accurately and robustly localize the patient. Preliminary laboratory results on both a radius-bone phantom and human subjects are presented.

Computer Systems↗