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Biomedical subjects

Thomas J Gill

Publications and source records attributed to Thomas J Gill.

At least 37 records · Page 2Linked to original sources
PubMed2005

Tissue engineering for meniscus repair.

Meniscus injury is common in today's active society. Despite the frequent presentation of meniscus injury, the decision to repair or resect a torn meniscus is not always straightforward. Current repair techniques are effective in the peripheral vascularized meniscus, but their success is not dependable in the avascularized zone. Tissue engineering, a discipline that combines the technologies of cell culture and biodegradable scaffolds to deliver a cellular repair, may be one future answer to this problem. The concept of using cell-based repair for torn menisci could improve healing of lesions in the avascular zone and broadly expand the indication for repair rather than removal, obviating the need for meniscectomy. This article reviews current advances in the relatively new field of tissue engineering toward the development of a tissue-engineered meniscal repair technique.

Chondrocytes↗
PubMed2005

In vivo articular cartilage contact kinematics of the knee: an investigation using dual-orthogonal fluoroscopy and magnetic resonance image-based computer models.

BACKGROUND: Quantifying the in vivo cartilage contact mechanics of the knee may improve our understanding of the mechanisms of joint degeneration and may therefore improve the surgical repair of the joint after injury. OBJECTIVE: To measure tibiofemoral articular cartilage contact kinematics during in vivo knee flexion. STUDY DESIGN: Descriptive laboratory study. METHODS: Orthogonal fluoroscopic images and magnetic resonance image-based computer models were used to measure the motion of the cartilage contact points during a quasi-static lunge in 5 human subjects. RESULTS: On the tibial plateau, the contact point moved in both the anteroposterior and the mediolateral directions during knee flexion. On the medial tibial plateau, flexion angle did not have a statistically significant effect on the location of the contact points. The total translation of the contact point from full extension to 90 degrees of flexion was less than 1.5 mm in the anteroposterior direction, whereas the translation in the mediolateral direction was more than 5.0 mm. In the anteroposterior direction, the contact points were centered on the medial tibial plateau. On the lateral tibial plateau, there was a statistically significant difference between the location of the contact point at full extension and the locations of the contact points at other flexion angles in the anteroposterior direction. No significant difference was detected between the location of the contact points at other flexion angles. The overall range of contact point motion was about 9.0 mm in the anteroposterior direction and about 4.0 mm in the mediolateral direction. The contact points were primarily on the inner half of the medial and lateral tibial plateaus (the half closest to the tibial spine). The contact points on both femoral condyles were also on the inner half of the condyles (near the condylar notch). CONCLUSIONS: The tibiofemoral contact points move in 3 dimensions during weightbearing knee flexion. The medial tibiofemoral contact points remained within the central portion of the tibial plateau in the anteroposterior direction. Both the medial and lateral tibiofemoral contact points were located on the inner portions of the tibial plateau and femoral condyles (close to the tibial spine), indicating that the tibial spine may play an important role in knee stability. CLINICAL RELEVANCE: The results of this study may provide important insight as to the mechanisms contributing to the development of osteoarthritis after ligament injuries.

Adult↗
PubMed2005

The effect of anterior cruciate ligament reconstruction on knee joint kinematics under simulated muscle loads.

BACKGROUND: Numerous studies have investigated anterior stability of the knee during the anterior drawer test after anterior cruciate ligament reconstruction. Few studies have evaluated anterior cruciate ligament reconstruction under physiological loads. PURPOSE: To determine whether anterior cruciate ligament reconstruction reproduced knee motion under simulated muscle loads. STUDY DESIGN: Controlled laboratory study. METHODS: Eight human cadaveric knees were tested with the anterior cruciate ligament intact, transected, and reconstructed (using a bone-patellar tendon-bone graft) on a robotic testing system. Tibial translation and rotation were measured at 0 degrees, 15 degrees, 30 degrees, 60 degrees, and 90 degrees of flexion under anterior drawer loading (130 N), quadriceps muscle loading (400 N), and combined quadriceps and hamstring muscle loading (400 N and 200 N, respectively). Repeated-measures analysis of variance and the Student-Newman-Keuls test were used to detect statistically significant differences between knee states. RESULTS: Anterior cruciate ligament reconstruction resulted in a clinically satisfactory anterior tibial translation. The anterior tibial translation of the reconstructed knee was 1.93 mm larger than the intact knee at 30 degrees of flexion under anterior load. Anterior cruciate ligament reconstruction overconstrained tibial rotation, causing significantly less internal tibial rotation in the reconstructed knee at low flexion angles (0 degrees-30 degrees) under muscle loads (P < .05). At 30 degrees of flexion, under muscle loads, the tibia of the reconstructed knee was 1.9 degrees externally rotated compared to the intact knee. CONCLUSIONS: Anterior cruciate ligament reconstruction may not restore the rotational kinematics of the intact knee under muscle loads, even though anterior tibial translation was restored to a clinically satisfactory level under anterior drawer loads. These data suggest that reproducing anterior stability under anterior tibial loads may not ensure that knee joint kinematics is restored under physiological loading conditions. CLINICAL RELEVANCE: Decreased internal rotation of the knee after anterior cruciate ligament reconstruction may lead to increased patellofemoral joint contact pressures. Future anterior cruciate ligament reconstruction techniques should aim at restoring 3-dimensional knee kinematics under physiological loads.

Anterior Cruciate Ligament↗
PubMed2004

In vivo elongation of the anterior cruciate ligament and posterior cruciate ligament during knee flexion.

BACKGROUND: Most knowledge regarding cruciate ligament function is based on in vitro experiments. PURPOSE: To investigate the in vivo elongation of the functional bundles of the anterior cruciate ligament and posterior cruciate ligament during weightbearing flexion. HYPOTHESIS: The biomechanical role of functional bundles of the anterior cruciate ligament and posterior cruciate ligament under in vivo loading is different from that measured in cadavers. STUDY DESIGN: In vivo biomechanical study. METHODS: Elongation of the anterior cruciate ligament and posterior cruciate ligament was measured during a quasi-static lunge using imaging and 3-dimensional computer-modeling techniques. RESULTS: The anterior-medial bundle of the anterior cruciate ligament had a relatively constant length from full extension to 90 degrees of flexion. The posterior-lateral bundle of the anterior cruciate ligament decreased in length with flexion. Both bundles of the posterior cruciate ligament had increased lengths with flexion. CONCLUSION: The data did not demonstrate the reciprocal function of the 2 bundles of the anterior cruciate ligament or the posterior cruciate ligament with flexion observed in previous studies. Instead, the data suggest that there is a reciprocal function between the anterior cruciate ligament and posterior cruciate ligament with flexion. The anterior cruciate ligament plays a more important role in low-flexion angles, whereas the posterior cruciate ligament plays a more important role in high flexion. CLINICAL RELEVANCE: Understanding the biomechanical role of the knee ligaments in vivo is essential to reproduce the structural behavior of the ligament after injury (especially for 2-bundle reconstructions) and thus improve surgical outcomes.

Adult↗
PubMed2004

The effect of posterior knee capsulotomy on posterior tibial translation during posterior cruciate ligament tibial inlay reconstruction.

PURPOSE: To measure the biomechanical effect of the surgical capsulotomy made during a posterior cruciate ligament reconstruction using the tibial inlay technique. HYPOTHESIS: The posterior capsule contributes to posterior tibial stability. STUDY DESIGN: Controlled laboratory experiment. METHODS: Six knee specimens were tested on a robotic testing system from 0 degrees to 120 degrees of flexion with the posterior cruciate ligament intact and resected and with a posterior capsulotomy identical to that performed during tibial inlay reconstruction (sham surgery). A longitudinal incision with medial and lateral soft tissue stripping sufficient to mount an inlay bone block and pass an Achilles tendon graft into the knee was made in the oblique popliteal ligament, muscle belly of the popliteus, and posterior capsule. The posterior tibial translation was measured under a posterior tibial load of 130 N at multiple flexion angles. RESULTS: Capsulotomy increased the posterior laxity compared with the posterior cruciate ligament-resected knee at every flexion angle. An additional 0.97 +/- 0.48 mm, 0.65 +/- 0.47 mm, 0.56 +/- 0.33 mm, 0.48 +/- 0.38 mm, and 0.94 +/- 0.60 mm of posterior laxity was recorded at 0 degrees, 30 degrees, 60 degrees, 90 degrees, and 120 degrees of flexion, respectively. These values were all statistically significant (P < .001). CONCLUSIONS: A posterior capsulotomy alone, without associated posteromedial or posterolateral disruption, produces additional posterior tibial translation in vitro compared with posterior cruciate ligament-deficient knee with intact capsule. CLINICAL RELEVANCE: Damage to the posterior capsule may contribute to the residual posterior laxity noted clinically after posterior cruciate ligament reconstruction.

Achilles Tendon↗
PubMed2004

Tibial plateau fracture following anterior cruciate ligament reconstruction.

A case is presented of a tibial plateau fracture after previous anterior cruciate ligament reconstruction using patellar tendon autograft. The tibial plateau fracture occurred through the transosseous tibial tunnel and followed a torsional injury to the involved extremity. The stress riser effect of the transosseous tibial tunnel and the anatomic location of the cortical defect probably facilitated development of the fracture. Minimally invasive fixation of the fracture was effective in preserving knee stability without need for revision anterior cruciate ligament reconstruction.

Accidental Falls↗
PubMed2004

Arthroscopic treatment of the arthrofibrotic knee.

The management of motion loss of the knee is challenging. A clear understanding of the pathoanatomic causes of motion loss is necessary to establish a careful and rational approach to treatment. Early recognition and physical therapy are effective for the majority of patients, but when these conservative measures fail, operative intervention is indicated. The purpose of this article is to outline a comprehensive approach to the arthroscopic evaluation and treatment of the arthrofibrotic knee. This technique is designed to allow the surgeon to systematically address the numerous causes of motion loss of the knee.

Arthroscopy↗
PubMed2004

In vivo tibiofemoral contact analysis using 3D MRI-based knee models.

This paper quantified the motion of the tibiofemoral contact points during in vivo weight bearing flexion using MRI- based 3D knee models and two orthogonal fluoroscopic images. The contact points on the medial and lateral tibial plateau were calculated by finding the centroid of the intersection of the tibial and femoral cartilage layers and by using the bony geometry alone. Our results indicate that the medial femoral condyle remains in the central portion of the tibial plateau and the lateral condyle translates posteriorly with increasing flexion. Using the bony contact model increased the total translation of the medial and lateral condyles by 250 and 55%, respectively, compared to the cartilage contact model. These results suggest that using the bony geometry alone may not accurately represent the articular surfaces of the knee. Articular cartilage geometry may have to be used to accurately quantify tibiofemoral contact.

Adult↗
PubMed2004

Triceps tendon ruptures in professional football players.

BACKGROUND: Distal rupture of the triceps tendon is a rare injury, and treatment guidelines are not well established. HYPOTHESIS: Football players with triceps tendon ruptures will be able to return to their sport with minimal functional deficits. STUDY DESIGN: Uncontrolled retrospective review. METHODS: Twenty-one partial and complete ruptures of the triceps tendon were identified in 19 National Football League players over a period of 6 years. Team physicians retrospectively reviewed training room, clinical, and operative notes for each of these players. RESULTS: Most of the injured players were linemen. The most common mechanism of injury was an eccentric load to a contracting triceps. Seven players had prodromal symptoms prior to injury, and 5 had received a cortisone injection. Eleven elbows with complete tears underwent surgical repair. Of 10 players with partial tears, 6 healed without surgery. One player suffered a subsequent complete tear requiring surgery, and 3 with residual pain and weakness underwent surgical repair following the season. Two surgical complications occurred, both requiring a second operation. All of the players but 1 returned to play at least one season of professional football after their injury. CONCLUSIONS: Partial triceps tendon ruptures can heal without functional deficit. Surgical repair for complete ruptures generally produces good functional results and allows return to play.

Adult↗
PubMed2004

The effect of length on the structural properties of an Achilles tendon graft as used in posterior cruciate ligament reconstruction.

BACKGROUND: The clinical outcomes of posterior cruciate ligament reconstruction are varied. No previous studies have investigated the effect of graft length on the structural properties of the graft. HYPOTHESIS: Graft length significantly affects the structural properties of posterior cruciate ligament grafts. STUDY DESIGN: Controlled laboratory study. METHODS: Eight Achilles tendon grafts were tested under tensile loads up to 400 N at 3 different lengths: long (75 mm), medium (48 mm), and short (34 mm). These 3 lengths represent midtunnel fixation, inlay fixation, and fixation near the ligament insertions. RESULTS: Shortening the graft from both long to medium and from medium to short increased the stiffness by approximately 25%. Long and medium grafts displaced significantly more than medium and short grafts, respectively. CONCLUSION: The effective length of a graft, which is determined by where it is fixed, should be considered an important variable in posterior cruciate ligament reconstruction.

Achilles Tendon↗
PubMed2004

In vivo function of the posterior cruciate ligament during weightbearing knee flexion.

BACKGROUND: Current knowledge of posterior cruciate ligament function is mainly based on in vitro cadaveric studies. There are few studies on the in vivo function of the posterior cruciate ligament. The objective of the study was to quantify the multidimensional deformation of the posterior cruciate ligament. HYPOTHESIS: During in vivo weightbearing flexion, the posterior cruciate ligament undergoes complex 3-dimensional deformations, including elongation, twist, and changes in orientation. STUDY DESIGN: In vivo biomechanical study. METHODS: Magnetic resonance images of 5 human knees were used to create 3-dimensional computer models of each subject's knee, including the insertion areas of the posterior cruciate ligament. Orthogonal fluoroscopic images of each subject's knee were acquired as a quasi-static lunge was performed. The images and computer models were used to reproduce the in vivo motion of the knee. The relative motion of the femoral and tibial insertions was described in terms of elongation, twist, elevation (the angle between the tibial plateau and posterior cruciate ligament, measured in the sagittal plane), and deviation (mediolateral orientation, measured in plane of tibial plateau). RESULTS: The length of the posterior cruciate ligament increased significantly with increasing flexion. It twisted almost 80 degrees as the knee flexed from 0 degrees to 90 degrees . The elevation angle remained relatively constant at 50 degrees . The deviation angle was medially oriented by 20 degrees at full extension, then decreased to approximately 10 degrees at 30 degrees through 90 degrees of flexion. CONCLUSION: The posterior cruciate ligament undergoes a complex twisting motion as it elongates with flexion. CLINICAL RELEVANCE: During reconstruction, the tunnels and graft may need to be placed such that the multidimensional deformation of the intact posterior cruciate ligament is reproduced.

Adult↗
PubMed2003

Traumatic labral avulsion from the stable rim: a constant pathology in displaced transverse acetabular fractures.

INTRODUCTION: During the treatment of a malunited transverse acetabular fracture, a hitherto undescribed extended avulsion of the labrum from the stable acetabular fragment was found. Based on the labral pathomorphology present in this case, the hypothesis was put forward that traumatic acetabular labral avulsions are a constant phenomenon in transverse acetabular fractures. PATIENTS AND METHODS: Fourteen patients underwent capsulotomy and/or surgical dislocation of the involved hip to facilitate open reduction and internal fixation of transverse acetabular fractures. RESULTS: In all cases, the labrum was partially or completely detached from the superior acetabular rim. In eight cases with bucket-handle tears of the labrum from the stable superior fragment, the injured portion was resected back to normal margins. In one case the labrum was avulsed with an attached piece of bone and was repaired by screw fixation. Small separations of the labrum from the underlying acetabular rim occurred at the level of the fractures in five cases with minor displacement and received no treatment. CONCLUSION: With displaced transverse acetabular fractures, consideration should be given to opening the joint at the time of open reduction and internal fixation to look for associated intracapsular injuries. An avulsed portion of the labrum should be left if stable and undamaged. If unstable and damaged, it is probably better resected and if unstable but intact and/or attached to a bony fragment, it should be repaired.

Acetabulum↗
PubMed2002

Fractures and tendon injuries of the athletic shoulder.

Athletic injuries in the shoulder range from a routine strain or sprain to a potentially disabling fracture or tendon rupture. The level of sports participation plays an important role in diagnosis and treatment. The nonprofessional athlete may be more likely to sustain injuries secondary to under-training or improper technique. The professional athlete may be capable of play under much higher velocities and applied loads and, therefore, may be subject to higher energy trauma than the amateur athlete. In addition to standard treatment considerations, return to play time must also be decided. Decisions regarding definitive treatment may be modulated depending on an athlete's desire to return to his or her previous level of competition.

Acute Disease↗
PubMed2002

Anterior cruciate ligament reconstruction the two-incision technique.

Historically, the two-incision technique for anterior cruciate ligament (ACL) reconstruction was the standard of practice. It allows predictable, near-anatomic placement of the femoral tunnel and provides highly reproducible results with few complications. There are several major advantages of the two-incision technique over endoscopic methods. These include consistent femoral tunnel placement, elimination of concern for "blowing out the back wall," elimination of the problem of graft-tunnel mismatch, elimination of the problem of screw divergence, and ease of use for revision ACL reconstruction procedures. The angle of the ACL graft is also more anatomic, matching the angle of the native ACL. In this chapter we present our technique for reconstruction of the ACL using the two-incision approach. Indications for its use are discussed. Advantages and disadvantages of the two-incision method compared with the all-endoscopic approach are reviewed.

Anterior Cruciate Ligament Injuries↗
PubMed2002

Biomechanical consequences of PCL deficiency in the knee under simulated muscle loads--an in vitro experimental study.

The mechanism of chronic degeneration of the knee after posterior cruciate ligament (PCL) injury is still not clearly understood. While numerous biomechanical studies have been conducted to investigate the function of the PCL with regard to antero-posterior stability of the knee, little has been reported on its effect on the rotational stability of the knee. In this study, eight cadaveric human knee specimens were tested on a robotic testing system from full extension to 120 degrees of flexion with the PCL intact and with the PCL resected. The antero-posterior tibial translation and the internal-external tibial rotation were measured when the knee was subjected to various simulated muscle loads. Under a quadriceps load (400 N) and a combined quadriceps/hamstring load (400/200 N), the tibia moved anteriorly at low flexion angles (below 60 degrees). Resection of the PCL did not significantly alter anterior tibial translation. At high flexion angles (beyond 60 degrees), the tibia moved posteriorly and rotated externally under the muscle loads. PCL deficiency significantly increased the posterior tibial translation and external tibial rotation. The results of this study indicate that PCL deficiency not only changed tibial translation, but also tibial rotation. Therefore, only evaluating the tibial translation in the anteroposterior direction may not completely describe the effect of PCL deficiency on knee joint function. Furthermore, the increased external tibial rotations were further hypothesized to cause elevated patello-femoral joint contact pressures. These data may help explain the biomechanical factors causing long-term degenerative changes of the knee after PCL injury. By fully understanding the etiology of these changes, it may be possible to develop an optimal surgical treatment for PCL injury that is aimed at minimizing the long-term arthritic changes in the knee joint.

Aged↗
PubMed2002

Evolutionary genetics and infertility.

PROBLEM: Mapping the human genome and advances in human evolution indicate a critical role for genetics in the study of reproduction. METHOD OF STUDY: Literature in human evolution, genetics and reproduction. RESULTS: This paper will focus on three points: (1) the course of primate evolution, (2) implications of this course for reproduction in humans, and (3) evolutionary mechanisms. Reproduction is the driving force of evolution, and sex selection is the important factor in determining reproductive activity. The hypothesis will be presented that the reproductive inefficiency of Homo sapiens (one of four pregnancies succeeds) is the consequence of the development of genetic isolation from other species of Homo that was necessary to drive the evolution of Homo sapiens. This hypothesis is based on the evidence that Homo sapiens and Homo neanderthalensis are separate species and that intermating would not yield fertile offspring (Haldane's Rule). This mating barrier involves zoological and linguistic differences and genetic mechanisms preventing fertile interspecies mating (chromosomal incompatibilities, disruption of genomic imprinting and recessive lethal defects). CONCLUSIONS: The medical and philosophical implications of modern reproductive technologies that may circumvent mating barriers must be addressed prospectively: propagation of genetic defects that would be eliminated by natural selection; the specter of 'genetic enhancement'; human cloning; and attempts to control the future direction of the evolution of Homo sapiens.

Animals↗
PubMedDate not supplied

Can the impingement test predict outcome after arthroscopic subacromial decompression?

The impingement test, placement of local anesthetic in the subacromial space, is considered a useful tool in diagnosing impingement syndrome. The purpose of this study was to examine the predictive value of the impingement test with respect to outcome after arthroscopic subacromial decompression. Fifty-five patients who had a preoperative impingement test were evaluated at 3 and 12 months postoperatively. We noted 88% satisfactory results in patients in whom the impingement test was positive, with only 63% satisfactory results at 3 months and 60% satisfactory results at 12 months in patients in whom the impingement test was negative. Although workers' compensation patients tended to have lower scores than others, the impingement test result was more predictive of outcome than was compensation status. Impingement test results and preoperative American Shoulder and Elbow Surgeons scores were independent predictors of postoperative American Shoulder and Elbow Surgeons scores. Our evidence indicates that the impingement test can be used as a predictor of outcome for patients with impingement syndrome treated by arthroscopic subacromial decompression.

Adult↗