Biomedical subjects

I K Lo

Publications and source records attributed to I K Lo.

13 recordsLinked to original sources

PubMed2002

The cellular matrix: a feature of tensile bearing dense soft connective tissues.

The term connective tissue encompasses a diverse group of tissues that reside in different environments and must support a spectrum of mechanical functions. Although the extracellular matrix of these tissues is well described, the cellular architecture of these tissues and its relationship to tissue function has only recently become the focus of study. It now appears that tensile-bearing dense connective tissues may be a specific class of connective tissues that display a common cellular organization characterized by fusiform cells with cytoplasmic projections and gap junctions. These cells with their cellular projections are organised into a complex 3-dimensional network leading to a physically, chemically and electrically connected cellular matrix. The cellular matrix may play essential roles in extracellular matrix formation, maintenance and remodelling, mechanotransduction and during injury and healing. Thus, it is likely that it is the interaction of both the extracellular matrix and cellular matrix that provides the basis for tissue function. Restoration of both these matrices, as well as their interaction must be the goal of strategies to repair these connective tissues damaged by either injury or disease.

Animals↗

PubMed2001

The radioulnar ratio: a new method of quantifying distal radioulnar joint subluxation.

Computed tomography was used to image the distal radioulnar joint (DRUJ) for instability. Four methods were used to quantify subluxation of the DRUJ: the Mino criteria, the epicenter method, the congruency method, and a new method called the radioulnar ratio (RUR). Validity of the various methods was evaluated in clinical and laboratory situations. Rheumatoid patients with symptomatic DRUJ pathology had significantly more abnormal RUR values (100% vs 73% [epicenter method] and 88% [Mino criteria]). The RUR detected instability sooner in a progressive laboratory-induced instability model. The intraobserver and interobserver reliability of the RUR was high, with intraclass correlation coefficients of 0.89 and 0.87, respectively. The RUR demonstrated superior performance in the diagnosis of DRUJ subluxation.

Adult↗

PubMed2001

The development of a disease-specific quality of life measurement tool for osteoarthritis of the shoulder: The Western Ontario Osteoarthritis of the Shoulder (WOOS) index.

OBJECTIVE: The purpose of this study was to develop and validate a disease-specific quality of life measurement tool for osteoarthritis (OA) of the shoulder. METHODS: An instrument which could be used as the primary outcome measure in clinical trials involving patients with OA of the shoulder was developed using a specific methodological protocol: (1) identification of a specific patient population; (2) item generation; (3) item reduction; (4) pre-testing of the prototype questionnaire and (5) determining the validity, reliability and responsiveness of the final questionnaire. RESULTS: The final instrument contains 19 items, each with a visual analog response option for the four domains (six questions for pain and physical symptoms, five questions for sport, recreation and work, five questions for lifestyle function and three questions for emotional function). Ten of the 19 questions had not been identified previously on other shoulder measurement tools. The instrument proved to be valid by demonstrating predicted correlations with previously published shoulder measures, global health status measure and range of motion. The new instrument was also more responsive than other shoulder measurement tools, a global health status measure and range of motion. CONCLUSIONS: Since the patient's own perception of changes in health status is the most important indicator of the success of treatment we suggest that this measurement tool be used as the primary outcome in clinical evaluation of various treatments for OA of the shoulder and monitoring patients over time.

Adult↗

PubMed2001

A biomechanical analysis of intrascaphoid compression using the 3.00 mm Synthes cannulated screw and threaded washer: an in vitro cadaveric study.

This study evaluated the compressive capabilities of the 3.0 mm Synthes cannulated screw and threaded washer. A transverse osteotomy was performed at the waist of eight cadaveric scaphoids and a custom-designed load cell was inserted before internal fixion with a 3.0 mm cannulated screw and threaded washer. The mean intrascaphoid compression achieved was 108 (SD, 60) N. This compressive force is comparable to that produced by standard cortical screws.

Aged↗

PubMed2001

Effect of fatigue on knee proprioception: implications for dynamic stabilization.

The high incidence of injuries that occur later during a session of sports or recreational activities suggests that fatigue may contribute to altered neuromuscular control of the lower limb and an individual's subsequent altered ability to dynamically stabilize the knee joint. One possible mechanism is a fatigue-mediated alteration in proprioception. This paper reviews experimental evidence of fatigue-induced changes in knee joint position sense and movement sense, or kinesthesia. We will discuss the possible physiological mechanisms behind these changes, including the role of joint and muscle receptors in proprioception and neuromuscular control of the knee, and the role of fatigue in changes in afferent output from muscle and joint receptors. We will then explore the implications that alteration in proprioception may have for dynamic stabilization of the knee joint.

Afferent Pathways↗

PubMed1999

The gross morphology of torn human anterior cruciate ligaments in unstable knees.

To evaluate the presence and incidence of reattachments of torn human anterior cruciate ligaments (ACL), we prospectively investigated 101 patients undergoing arthroscopic ACL reconstruction to study the intra-articular morphology of ACLs under circumstances in which functional healing had failed. Results showed that roughly 72% of these unstable knees had reattachment of the torn ACL to the posterior cruciate ligament (PCL). Eighteen percent had no signs of ACL reattachment but only 2% of previously torn ACLs were absent. These results suggest that even in chronic situations in which the knee remains functionally unstable, human ACLs rarely resorb. It also suggests that torn human ACLs commonly reattach in the knee, mainly to the PCL via a process that is consistent with scarring. While the function of these reattachments is clearly inadequate in people with unstable knees because of a combination of reattachment location, scar quantity, or quality, these results nonetheless show that the intra-articular environment in humans often maintains ACL stumps and it is not totally inhibitory to ACL reattachment via some biological process.

Adolescent↗

PubMed1998

Comparison of mRNA levels for matrix molecules in normal and disrupted human anterior cruciate ligaments using reverse transcription-polymerase chain reaction.

Midsubstance samples of anterior cruciate ligaments from seven normal human cadaver knees (16-50 years old) were harvested and compared with midsubstance pieces of scarred anterior cruciate ligaments from 30 patients (15-40 years old). RNA was isolated from each ligament, and the expression of type-I collagen, type-III collagen, biglycan, decorin, lumican, and tissue inhibitor of metalloproteinase-1 was evaluated by quantitative reverse transcription-polymerase chain reaction with use of beta-actin as the housekeeping gene. Data for injured ligaments were further compared statistically as a function of time after injury to better define patterns of cellular expression over time. Our hypothesis was that injured ligaments would show minimal cellular activity and decreasing activity over time. The results revealed that both normal and injured anterior cruciate ligaments contain cells that express mRNA for all molecules studied. However, cells in injured ligaments express much higher, but still proportional, quantities of message for type-I collagen and type-III collagen (p < 0.000001) and higher quantities of biglycan (p < 0.02) and tissue inhibitor of metalloproteinase-1 (p < 0.0003) than do cells in normal anterior cruciate ligaments. These levels remained elevated for longer than 1 year after injury. Linear regression analysis showed biglycan expression correlated with time from injury (r2 = -0.69; p = 0.007). These results collectively demonstrate that injured human anterior cruciate ligaments contain cells that express scar-like molecules and that the injured ligaments are likely continuing to remodel matrix over time. Furthermore, they suggest that human anterior cruciate ligaments have not failed to heal due to the failure of scar formation per se. The quality and quantity of this scar remain questionable; however, the possibility of its enhancement as a healing strategy for human anterior cruciate ligaments cannot be dismissed.

Adolescent↗

PubMed1998

The outcome of tendon transfers for C6-spared quadriplegics.

The purpose of this study was to review retrospectively and evaluate a uniform group of C6-spared quadriplegics who had similar surgical procedures. Eight patients undergoing 12 procedures were reviewed at an average of 3.8 years follow-up. There were three bilateral procedures. All patients had extensor carpi radialis longus to flexor digitorum profundus and brachioradialis to flexor pollicis longus transfers to improve grip strength and key pinch. All patients reported subjective improvements in quality of life, activities of daily living and patient-centred goals. There were six excellent and two good results. Objective improvements included mild improvements in key pinch and grip strength.

Activities of Daily Living↗

PubMed1998

A biomechanical analysis of intrascaphoid compression using the Herbert scaphoid screw system. An in vitro cadaveric study.

The purpose of this study was to evaluate the compressive capabilities of the Herbert scaphoid screw system. A transverse osteotomy was performed at the waist of eight scaphoids removing a 3 mm wafer of bone. A custom-designed load washer was inserted within this defect to measure intrascaphoid compression during Huene guide application, during screw insertion, after screw insertion and after guide release. The intrascaphoid compression was noted to peak during screw insertion; however it dramatically decreased without any clinical subjective evidence of decreased insertional torque by the surgeon. The average final compression as a percentage of maximal compression was 38 (SD 26) %.

Aged↗

PubMed1998

Anterior cruciate ligament injuries in the skeletally immature patient.

Anterior cruciate ligament injury in the skeletally immature is becoming increasingly recognized and reported. History taking and physical examination based on the principles of ACL injuries in adults, with adjuncts such as arthroscopy and MRI, are effective in diagnosing ACL injury in the young patient. Evaluation of the young patient's true level of skeletal immaturity by comparison with family growth history, examination for signs of sexual maturity, and radiographic evaluation is critical. The risk of physeal damage with surgical treatment is related to the immaturity of the distal femoral and proximal tibial physes. The functional results of nonsurgical treatment of ACL injury, either as an attempt at definitive treatment or as a temporizing plan until skeletal maturity occurs, are poor and the risks of reinjury and further meniscal and cartilage damage are significant. Surgical treatment for primary repair or extra-articular reconstruction alone has not proven to be efficacious. In the adolescent patient who is approaching skeletal maturity, risk of physeal injury is low and intra-articular reconstruction can be performed as in the adult patient. Results with respect to decreased laxity and return to athletic activities mirror those described in adults. In patients with significant growth remaining, however, surgical treatment carries much higher risks of physeal damage and subsequent deformity. Yet, as noted above, intra-articular reconstruction in truly skeletally immature patients using a soft-tissue graft through a transphyseal tibial tunnel of moderate or small diameter and the over-the-top position on the femur has not been shown to cause early physeal closure, limb-length discrepancy, or angular deformity. In humans, the maximum diameter of graft tunnel that will not cause physeal closure has not been determined Animal studies have shown that the tibial physis can be very sensitive to drilling. Therefore it is wise to use moderate tunnel diameters. Bone-patellar tendon-bone grafts have been used with success in patients closer to skeletal maturity. Their use has not been reported in the very skeletally immature knee and cannot be recommended because of the presumed high risk of physeal closure with a bone plug traversing the physis. It is hoped that improved understanding of the ACL injury in the skeletally immature patient will provide treatment options that will restore enduring knee function and prevent early arthrosis.

Adolescent↗

PubMed1997

The outcome of operatively treated anterior cruciate ligament disruptions in the skeletally immature child.

The purpose of this study was to evaluate the outcome of transphyseal ligament reconstruction in skeletally immature children with midsubstance anterior cruciate ligament (ACL) disruption. Five consecutive patients (mean age, 12.9 years; range, 8 to 14 years) with radiographically documented "wide" open growth plates and a minimum of 5 cm of expected remaining growth, underwent intra-articular reconstruction of the ACL. Operative treatment included three ACL reconstructions using hamstring tendons and two with quadriceps patellar tendon. All involved a centrally placed 6-mm or smaller tibial drill hole through an open physis and graft placement in an over-the-top position on the femur. At an average follow-up of 7.4 years (range, 4.5 to 9.9 years), no patient had a positive anterior drawer, Lachman, or pivot shift test. On KT-1000 arthrometer testing, all patients had 3 mm or less of increased anterior-posterior displacement (mean +/- SD = 1.0 +/- 1.6 mm). Magnetic resonance imaging showed that four tibial physes had fused in a symmetric fashion and one was still open. Orthoroentgenograms showed that no patient had a significant leg length discrepancy (-0.8 mm +/- 3.4 mm). The mean increase in height postoperatively was 17.7 cm (range, 7.6 to 31.0 cm). Overall, using the International Knee Documentation Committee (IKDC) evaluation form, there were four patients with grade A and one with grade C. The one patient with a poor IKDC grade had sustained a subsequent patellar dislocation with osteochondral fracture. In conclusion, ACL reconstruction using small drill holes placed through open tibial physes does not seem to adversely affect outcome or future growth.

Adolescent↗

PubMed1997

Operative versus nonoperative treatment of acute Achilles tendon ruptures: a quantitative review.

OBJECTIVE: To determine the optimal treatment of acute Achilles tendon ruptures. DATA SOURCES: A comprehensive search for all of the English articles published between 1959 and 1997. STUDY SELECTION: All of the articles were reviewed independently by at least three of the four authors to decide on eligibility based on predetermined criteria. Disagreements were discussed and then settled, if necessary, by a majority vote. DATA EXTRACTION: Eligible studies were reviewed independently, and data were extracted by using standardized coding forms. Inconsistencies in data extraction were settled by discussion and majority vote. The main outcomes extracted were strength, time to return to work, frequency of return to sports, rerupture rate, and complications. Complications were divided into major, moderate, and minor categories. DATA SYNTHESIS: The overall rerupture rate was 2.8% for operatively treated and 11.7% for nonoperatively treated patients (p < 0.001). The rate of minor and moderate complications in operatively treated patients was 20 times that of nonoperatively treated patients. The difference in rates for major complications was not statistically significant. CONCLUSIONS: Although operative treatment provides a reduced rerupture rate compared with nonoperative treatment, the minor and moderate complication rate of operative treatment is 20 times greater. Treatment should be individualized to the concerns and health of the patient. Future clinical trials are necessary to determine the optimal method of both operative and conservative treatment.

Achilles Tendon↗

PubMed1994

Arthroscopic radial head excision.

Radial head excision is a commonly performed procedure used in the treatment of radial head disorders. Arthroscopic radial head excision has not been previously described in the literature. In this study we report the technique and results of arthroscopic excision of the radial head for posttraumatic arthritis.

Arthroscopy↗