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Biomechanics of skeletal muscle

Chapter by: Lorenz, Tobias; Campello, Marco; Pitman, Mark I
in: Basic biomechanics of the musculoskeletal system by Nordin, Margareta; Frankel, Victor H. [Eds]
Philadelphia : Lippincott Williams & Wilkins, c2001
pp. ?-?
ISBN: 9780683302479
CID: 1331622

Acute and chronic posterolateral rotatory instability of the knee

Chen, F S; Rokito, A S; Pitman, M I
Isolated posterolateral rotatory instability of the knee is an uncommon injury pattern that may result in significant degrees of functional disability. This injury complex can be a challenging diagnostic and therapeutic problem for the orthopaedic surgeon. The presence of associated ligamentous and soft-tissue injuries, resulting in combined instability patterns, further complicates management. The results of recent research have enhanced our understanding of the complex anatomy and biomechanics of the posterolateral aspect of the knee. Numerous surgical techniques have been described for both repair and reconstruction of the injured posterolateral structures; however, long-term functional results have been only moderately successful.
PMID: 10799095
ISSN: 1067-151x
CID: 215482

Inflammatory foreign-body reaction to an arthroscopic bioabsorbable meniscal arrow repair [Case Report]

Menche DS; Phillips GI; Pitman MI; Steiner GC
Various arthroscopic meniscal repair techniques have been developed in recent years to preserve meniscal function. We report the case of a patient with a failed arthroscopic meniscal repair demonstrating an inflammatory foreign-body reaction to bioabsorbable meniscal arrows
PMID: 10524827
ISSN: 0749-8063
CID: 6262

The treatment of isolated articular cartilage lesions in the young individual

Menche, D S; Vangsness, C T Jr; Pitman, M; Gross, A E; Peterson, L
The treatment of isolated articular cartilage defects is an evolving field in orthopaedic surgery today. We have summarized the basic science and clinical date on the treatment of isolated articular cartilage defects. Further long-term controlled studies are required in order to compare definitively the efficacy of treatments in this difficult clinical area. In future studies, inclusion/exclusion criteria must be detailed, and classification systems need to be standardized Comparative analysis can then be performed to assess the efficacy of various techniques.
PMID: 9571451
ISSN: 0065-6895
CID: 563552

Chondrocyte transplantation using a collagen bilayer matrix for cartilage repair

Frenkel, S R; Toolan, B; Menche, D; Pitman, M I; Pachence, J M
We have developed a novel, two-layered, collagen matrix seeded with chondrocytes for repair of articular cartilage. It consists of a dense collagen layer which is in contact with bone and a porous matrix to support the seeded chondrocytes. The matrices were implanted in rabbit femoral trochleas for up to 24 weeks. The control groups received either a matrix without cells or no implant. The best histological repair was seen with cell-seeded implants. The permeability and glycosaminoglycan content of both implant groups were nearly normal, but were significantly less in tissue from empty defects. The type-II collagen content of the seeded implants was normal. For unseeded implants it was 74.3% of the normal and for empty defects only 20%. The current treatments for articular injury often result in a fibrous repair which deteriorates with time. This bilayer implant allowed sustained hyaline-like repair of articular defects during the entire six-month period of observation
PMID: 9331046
ISSN: 0301-620x
CID: 105471

Radiographic changes in the knee after meniscal transplantation: an experimental study in a sheep model [Comment]

Pitman, M I
PMID: 8947414
ISSN: 0363-5465
CID: 3050002

A comparison of abrasion burr arthroplasty and subchondral drilling in the treatment of full-thickness cartilage lesions in the rabbit

Menche, D S; Frenkel, S R; Blair, B; Watnik, N F; Toolan, B C; Yaghoubian, R S; Pitman, M I
The purpose of this study was to observe the difference in healing of full-thickness articular cartilage defects treated with burr arthroplasty versus subchondral drilling. Cartilage was shaved off the medial femoral condyles of 39 rabbits without penetrating the subchondral plate. In left knees, two 2.0-mm holes were drilled into the condyle until bleeding was obtained. Right knees underwent a burr arthroplasty until punctate bleeding was observed. Animals were sacrificed at 6, 12, and 24 weeks postoperatively. Joint resurfacing and degenerative changes were evaluated grossly and histologically. Degenerative changes in the cartilage surface were observed with both treatments. Rabbits undergoing subchondral drilling had increased fibrocartilaginous healing with time, with a slight increase in degenerative changes. With burr arthroplasty, there was significant decrease in cartilaginous coverage of the exposed surface as well as progressive increase in degenerative changes. Although both techniques were suboptimal, histological evidence at 6 months suggests that subchondral drilling may result in a longer-lived repair than abrasion arthroplasty in the treatment of full-thickness lesions
PMID: 8783821
ISSN: 0749-8063
CID: 105473

The intraoperative evaluation of the neurosensory function of the anterior cruciate ligament in humans using somatosensory evoked potentials

Pitman, M I; Nainzadeh, N; Menche, D; Gasalberti, R; Song, E K
Most of the investigation of the properties of the anterior cruciate ligament (ACL) has focused on its biomechanical functions. There has been increasing interest in the study of the possible neuroreceptor function of the ACL and its role in providing important proprioceptive feedback. Anatomic and histologic studies in humans have shown the presence of neuroreceptors within the anterior cruciate ligament. Indirect evidence exists that proprioception is diminished in the ACL-deficient knee. However, direct evidence in humans of the actual origin of the afferent impulses from within the ACL itself is lacking. Measurement of direct electrical afferent activity, occurring on stimulation of the ACL, should provide this evidence. Somatosensory evoked potentials (SEP) measure the electric potentials evoked in the cerebral cortex upon stimulation of a peripheral neuroreceptor. Carried by the posterior columns of the spinal cord, they reflect activity of the proprioceptive fibers. During arthroscopic procedures performed on nine patients, the normal ACL was stimulated by the use of electrodes applied to the femoral end, midsubstance, and tibial end, and cortical potentials thus evoked were recorded. In all cases, SEPs were recorded at the cerebral cortex upon stimulation of the ACL. The greatest potentials were reported upon stimulation of the midsubstance of the ligament. These findings provide direct evidence for, and strongly support the presence of, active proprioceptive receptors within the intact anterior cruciate ligament of the human knee.
PMID: 1466702
ISSN: 0749-8063
CID: 160214

The effect of low-level Nd:YAG laser energy on adult articular cartilage in vitro

Spivak, J M; Grande, D A; Ben-Yishay, A; Menche, D S; Pitman, M I
Reports of laser energy applied to soft tissues in vitro and in vivo suggest both stimulation and inhibition of specific metabolic processes, depending on the type of laser, the energy density (ED) used, the mode of delivery, and type of tissue studied. An earlier in vitro study of Nd:YAG laser irradiation of articular cartilage indicated stimulation of both matrix and DNA synthesis for 6 days following laser exposure. In vivo reports on the ability of Nd:YAG laser energy to stimulate the healing of partial-thickness cartilage defects are conflicting. In the present study, a noncontact continuous-wave Nd:YAG laser beam of varying EDs was applied to full-thickness adult articular cartilage explants maintained in organ culture; the metabolic processes of chondrocyte DNA synthesis and matrix synthesis were followed over 2 weeks. For both canine and bovine cartilage, low-levels of laser energy (ED 51-127 J/cm2) stimulated matrix synthesis at 6-7 days following laser exposure, with a concomitant decrease in baseline DNA synthesis. By 12-14 days, however, these dose-dependent effects were no longer seen, with no significant differences from control noted for any of the laser energies studied. Histologic analysis of the cartilage explants following laser exposure showed no significant differences in cell number or morphology between sample and control groups; however, a decrease in matrix proteoglycan staining was seen in the highest laser energy group at all time points. These findings indicate that exposure to low-level noncontact Nd:YAG laser energy promotes a significant stimulation of cartilage matrix synthesis. However, a single exposure may not be sufficient to promote a sustained upregulation of cartilage metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)
PMID: 1550649
ISSN: 0749-8063
CID: 350662

A biomechanical study of tendon adhesion reduction using a biodegradable barrier in a rabbit model

Meislin RJ; Wiseman DM; Alexander H; Cunningham T; Linsky C; Carlstedt C; Pitman M; Casar R
Adhesion formation associated with tendon surgery is a widespread problem in which a healing tendon becomes adherent via scar tissue to surrounding structures such as bone, muscle, skin, tendon sheath, or other tendons. A model is described in which adhesions were generated reproducibly between the plantaris and Achilles tendons of the rabbit using a partial tenotomy, a Bunnel suture, and immobilization. Using this model, the effect of an absorbable barrier, INTERCEED (TC7), on adhesion formation was investigated. This material, which is a fabric comprised of oxidized regenerated cellulose, was found to diminish significantly the extent and severity of intertendinous adhesions, assessed both mechanically and histologically. No evidence of a foreign body reaction was observed
PMID: 10148985
ISSN: 1045-4861
CID: 32683