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Biomedical subjects

Andrew J Cosgarea

Publications and source records attributed to Andrew J Cosgarea.

At least 19 recordsLinked to original sources
PubMed2006

Technical errors during medial patellofemoral ligament reconstruction could overload medial patellofemoral cartilage: a computational analysis.

BACKGROUND: The influence of reconstruction of the medial patellofemoral ligament on the patellofemoral force and pressure distributions has not yet been investigated. HYPOTHESIS: Technical errors can cause tension to develop within a reconstructed medial patellofemoral ligament, which will adversely alter the normal patellofemoral force distribution by increasing the load applied to the medial cartilage. STUDY DESIGN: Controlled laboratory study. METHODS: Four computational knee models were used to simulate knee function from 30 degrees to 90 degrees of flexion with (1) an intact medial patellofemoral ligament, (2) an anatomically correct reconstruction using a double hamstring tendon autograft, (3) a 5-mm proximally malpositioned femoral attachment site, (4) a graft that is 3 mm shorter than the intact medial patellofemoral ligament, and (5) combined proximal malpositioning and a short graft. RESULTS: The results were similar for the intact and anatomically reconstructed medial patellofemoral ligament. Proximal malpositioning of the femoral attachment and using a short graft increased the graft tension during flexion, which decreased the lateral force and the lateral tilt moment acting on the patella. When a short graft was combined with proximal malpositioning, the compressive force applied to the medial cartilage at least doubled at low flexion angles, which increased the peak medial pressure by more than 50% at low flexion angles. CONCLUSION: When the medial patellofemoral ligament is reconstructed, small errors in graft length and position can dramatically increase the force and pressure applied to medial patellofemoral cartilage. CLINICAL RELEVANCE: Overloading the medial cartilage after medial patellofemoral ligament reconstruction could lead to degradation, pain, and arthrosis.

Cartilage, Articular↗
PubMed2006

Comparing two estimations of the quadriceps force distribution for use during patellofemoral simulation.

EMG analysis has indicated that the vastus lateralis and vastus medialis contribute less to the quadriceps moment during knee extension than the physiological cross-sectional areas (PCSA's) of the muscles indicate. Both PCSA- and EMG-based quadriceps force distributions were utilized while computationally simulating knee extension. For both distributions, a 10 degrees increase in the Q-angle and a 50% decrease in the force applied by the vastus medialis were simulated, and the influence of these changes on the resultant force and moment applied by the quadriceps muscles and the patella tendon was quantified. For both quadriceps force distributions, increasing the Q-angle increased the lateral force and the moment acting to rotate the distal patella laterally. Due to the relatively large forces initially attributed to the vastus medialis and vastus lateralis for the PCSA-based quadriceps force distribution, decreasing the vastus medialis force created a large force imbalance between these two muscles. For the PCSA-based quadriceps force distribution, decreasing the vastus medialis force increased the lateral rotation moment and the moment acting to tilt the patella laterally. For the EMG-based quadriceps force distribution, decreasing the vastus medialis force produced relatively little change in the tilt and rotation moments. For both quadriceps force distributions, increasing the Q-angle increased the maximum and mean cartilage pressure during flexion, but decreasing the vastus medialis force only increased the cartilage pressures for the PCSA-based quadriceps distribution. The choice of the initial quadriceps distribution can influence the outcome of patellofemoral simulation when manipulating quadriceps muscle forces.

Anatomy, Cross-Sectional↗
PubMed2006

Proximity of the popliteal artery to the PCL during simulated knee arthroscopy: implications for establishing the posterior trans-septal portal.

This study defines the sagittal distance from the posterior cruciate ligament (PCL) to the popliteal artery under simulated arthroscopic conditions. This information is relevant for posterior knee arthroscopy, particularly for the safe establishment of the posterior trans-septal portal. Measurements from the PCL to the popliteal artery were made on sagittal magnetic resonance images obtained in a previous study of 10 fresh-frozen cadaveric knees. The mean sagittal distance from the mid-PCL to the popliteal artery was 29.1 +/- 11 mm (range: 18-55 mm). The mean sagittal distance from the proximal PCL fovea to the popliteal artery was 9.7 +/- 5 mm (range: 3-16 mm). The results of this study provide the arthroscopist working in the posterior compartments of the knee with a more detailed knowledge of the anatomic relationship between the PCL and popliteal artery. This knowledge will help minimize the risk of iatrogenic vascular injury during arthroscopic knee surgery.

Aged↗
PubMed2006

Physical examination and imaging of the lateral collateral ligament and posterolateral corner of the knee.

Diagnosis of posterolateral corner injuries can be challenging. Understanding the mechanism of injury in combination with careful history taking and a thorough physical examination are crucial. Clinical findings may be subtle, especially in the acute setting. Specialized tests such as external rotation recurvatum test, posterolateral drawer test, reverse pivot shift test, and dial test are particularly helpful. A characteristic radiographic finding is the arcuate sign, whereas medial Segond fractures can be associated with posterolateral corner injuries. Magnetic resonance imaging is most useful when performed with a high strength magnet utilizing a coronal oblique technique. Prompt and accurate diagnosis of posterolateral corner injuries allows the orthopedist to initiate the appropriate repair and reconstruction procedures to assure optimum treatment results.

Collateral Ligaments↗
PubMed2004

Return to play after anterior cruciate ligament reconstruction.

The goal of knee ligament reconstruction is to return the athlete to the previous level of function as quickly and as safely as possible. The appropriate level of aggressiveness in returning the athlete to sport remains controversial. Information in the literature regarding safe return to play has been dominated by the anterior cruciate ligament (ACL) reconstruction literature. The basic concepts that hold true for returning the ACL-reconstructed athlete to play can be generalized to injuries treated nonoperatively as well. This article presents a review of the principles of rehabilitation following knee ligament reconstruction, with an emphasis on criteria for return to play.

Anterior Cruciate Ligament↗
PubMed2004

Evaluation of a computational model used to predict the patellofemoral contact pressure distribution.

One possible cause of patellofemoral pain syndrome is excessive lateral force acting on the patella. Although several treatment methods focus on decreasing the lateral force acting on the patella, the relationship between the lateral force and the patellofemoral contact pressure distribution is unclear. A computational model has been developed to determine how loading variations alter the patellofemoral force and pressure distributions for individual knees. The model allows variation in the quadriceps and patella tendon forces, and calculates the predicted contact pressure distribution using the discrete element analysis technique. To characterize the accuracy of the model, four cadaver knees were flexed on a knee simulator with three initial Q-angles, while recording the force and pressure distributions with a pressure sensor. A model of each knee was created from CT data. Using the external force applied to the knee, the geometry of the knee, and the quadriceps origin as input, the pressure distribution was calculated during flexion. Similar trends were noted for the computational and experimental results. The percentage of the total force applied to the lateral cartilage increased with the Q-angle. The maximum contact pressure increased during flexion. The maximum lateral contact pressure increased with the Q-angle for three knees. For the other knee, increasing the Q-angle decreased the maximum lateral pressure. The maximum medial contact pressure decreased as the Q-angle increased. By characterizing the influence of patellofemoral loading on the force and pressure distributions, the computational model could be used to evaluate treatment methods prescribed for patellofemoral pain.

Cadaver↗
PubMed2003

Clinical features of the different types of SLAP lesions: an analysis of one hundred and thirty-nine cases.

BACKGROUND: Previous studies have suggested that SLAP (superior labrum anterior posterior) lesions are a distinct clinical entity. The goals of this study were to define the prevalence, associated pathological findings, and clinical features of the different types of SLAP lesions with use of a common classification system. METHODS: Five hundred and forty-four patients undergoing shoulder arthroscopy for a variety of diagnoses were prospectively included in this consecutive case series. SLAP lesions were grouped with use of the Snyder classification. Demographic data, clinical data, and arthroscopic findings in the groups with SLAP lesions were compared with those in a control group with no SLAP lesion. RESULTS: Of 544 shoulder arthroscopy procedures, 139 (26%) demonstrated a SLAP lesion. One hundred and three (74%) of the SLAP lesions were Type I, twenty-nine (21%) were Type II, one (0.7%) was Type III, and six (4%) were Type IV. Most (123) of the SLAP lesions were found to be associated with other intra-articular lesions. Multivariate analysis revealed that a positive Speed test and a supraspinatus tear were significantly associated with Type-I lesions (p = 0.012 and p = 0.001, respectively). The findings associated with Type-II lesions differed according to the patient's age: Type-II lesions in patients who were forty years of age or younger were associated only with a Bankart lesion, whereas those in patients older than forty years of age were associated with a supraspinatus tear and osteoarthritis of the humeral head. Type-III and Type-IV lesions were associated with a high-demand occupation and a Bankart lesion. CONCLUSIONS: This study demonstrated that the prevalence, associated pathological findings, and clinical features of the different types of SLAP lesions vary with the patient population that is studied. Also, the clinical features and pathological findings associated with the different types of SLAP lesions often overlap. Isolated SLAP lesions with no associated pathological findings are uncommon, and care must be taken when ascribing symptoms to a SLAP lesion when other lesions are present. LEVEL OF EVIDENCE: Diagnostic study, Level IV-1 (case-control study). See p. 2 for complete description of levels of evidence.

Adolescent↗
PubMed2003

Arthrofibrosis of the knee following ligament surgery.

Arthrofibrosis of the knee is one of the most serious complications that can result from ligament surgery. Reported incidence of arthrofibrosis following anterior cruciate ligament reconstruction ranges from 4% to 35%. The loss of motion caused by arthrofibrosis can be even more disabling than the instability for which the reconstruction was performed, often requiring extensive physical therapy and/or surgical lysis of adhesions. With aggressive rehabilitation and modifications in the bracing of knees undergoing ligament reconstruction, the incidence of this complication has decreased significantly. Additionally, delaying anterior cruciate ligament reconstruction until the acute inflammatory period has resolved has also been shown to be a significant factor in the reduction of postoperative knee stiffness.

Anterior Cruciate Ligament↗
PubMed2003

Soleus and gastrocnemius muscle loading decreases anterior tibial translation in anterior cruciate ligament intact and deficient knees.

This study evaluated the effect of the gastrocnemius and soleus muscles on dynamic knee stability by studying the effect of passive calf muscle loading on anterior tibial translation in normal and anterior cruciate ligament (ACL) deficient knees. Anterior tibial translation was measured bilaterally in 12 anesthetized patients with unilateral ACL-deficient knees using a KT-1000 arthrometer. An ankle-foot orthosis was used to passively dorsiflex the ankle and generate tension in the calf muscles. As the ankle flexion angle was progressively changed from 30 degrees plantar flexion to 10 degrees dorsiflexion, anterior tibial translation decreased 43% and 37% with manual maximum force in normal and ACL-deficient knees, respectively (P < .0001). These findings suggest that the calf muscles may function as dynamic knee stabilizers. Anterior tibial translation also was measured in four cadaver knees. Significant decreases were seen in anterior tibial translation with progressive ankle dorsiflexion in ACL-intact specimens and after the ACL had been cut (P < .05). This effect persisted when the gastrocnemius muscle was cut, but was lost when the soleus muscle was released. The data suggest that the soleus muscle may play a role in dynamically stabilizing the knee.

Adolescent↗
PubMed2002

Arthroscopic proficiency: a survey of orthopaedic sports medicine fellowship directors and orthopaedic surgery department chairs.

PURPOSE: The goal of this study was to evaluate the opinion of sports medicine fellowship directors and orthopaedic surgery department chairpersons on how many repetitions the average resident needs to become proficient in several common arthroscopic procedures. TYPE OF STUDY: A cross-sectional study. METHODS: A questionnaire was mailed to all fellowship directors on a list maintained by the American Academy of Orthopaedic Surgeons and to all department chairpersons on a list maintained by the American Medical Association. Respondents were asked to estimate the number of operations needed for a trainee to reach minimal proficiency (able to perform procedure skin-to-skin with supervision) and proficiency (capable of performing procedure without supervision) for 5 common arthroscopic procedures: diagnostic knee scope, partial medial meniscectomy, anterior cruciate ligament (ACL) reconstruction, diagnostic shoulder scope, and subacromial decompression. RESULTS: A total of 164 of 230 (71%) people responded to the questionnaire. Department chairpersons who did not perform arthroscopy consistently estimated two thirds the number of operations that department chairpersons who did perform arthroscopy and nearly half the number of operations estimated by fellowship directors. Chairpersons who did perform arthroscopy had responses more similar to fellowship directors than to department heads who did not perform arthroscopy. CONCLUSIONS: These results indicate that, in the opinion of physicians involved in the education of residents and fellows, it may take a substantial number of repetitions to become proficient in arthroscopy. Physicians who perform little or no arthroscopy themselves may underestimate its difficulty. Interestingly, there was substantial variability in the number of repetitions estimated to achieve proficiency in all procedures. The results of this study may be helpful in designing arthroscopic training programs for orthopaedic residents or sports medicine fellows; however, the wide variability in opinions may indicate difficulty in reaching a consensus.

Arthroscopy↗
PubMed2002

Posterior cruciate ligament rupture alters in vitro knee kinematics.

Isolated posterior cruciate ligament injuries usually are treated nonoperatively, although some patients remain symptomatic, and degenerative changes within the patellofemoral joint and the medial compartment of the tibiofemoral joint have been seen in followup studies. In vitro simulation of knee squatting was done to quantify the influence of the posterior cruciate ligament on tibiofemoral and patellofemoral kinematics. For five knee specimens, knee kinematics were measured before and after sectioning the posterior cruciate ligament, and compared using a Wilcoxon signed rank test. The only kinematic parameters that changed significantly after sectioning the posterior cruciate ligament were the tibial posterior translation and patellar flexion. The posterior translation of the tibia increased significantly between 25 degrees and 90 degrees flexion. The average increase in the posterior translation exceeded 10 mm at 90 degrees flexion. The patellar flexion increased significantly from 30 degrees to 90 degrees flexion. The average patellar flexion increase peaked at 4.4 degrees at 45 degrees flexion. Increased tibial translation could adversely influence joint stability. Increased patellar flexion could increase the patellofemoral joint pressure, especially at the inferior pole, leading to degenerative changes within the patellofemoral joint.

Aged↗
PubMedDate not supplied

Neurovascular complications of knee arthroscopy.

During the last 3 decades, arthroscopy has revolutionized the way knee surgery is performed. The indications and the applications of arthroscopic procedures in the knee joint have enormously increased with the improvement in surgical technique and advent of new arthroscopic equipment. The use of arthroscopic techniques has led to a significant decrease in morbidity for the patient with intraarticular abnormalities, in terms of both diagnosis and surgical correction. Even though knee arthroscopy is a minimally invasive procedure with relatively low morbidity, it is not without risk of complications, of which neurovascular complications are among the most serious and devastating. The reported incidence of neurovascular complication is low, but it may be underestimated. Many neurovascular complications that occur are preventable with a thorough understanding of neurovascular anatomy, good preoperative and intraoperative planning, and attention to the details of basic techniques and the equipment used for the procedure. It is imperative that the surgeon who is performing arthroscopy be aware of these neurovascular complications, recognize them as early as possible, and initiate further evaluation and treatment as expeditiously as possible. In this article, the causes, management, prevention, and medicolegal implications of neurovascular complications of knee arthroscopy are reviewed.

Animals↗