Biomedical subjects

Michael J Strobel

Publications and source records attributed to Michael J Strobel.

6 recordsLinked to original sources

PubMed2006

Combined anterior cruciate ligament, posterior cruciate ligament, and posterolateral corner reconstruction with autogenous hamstring grafts in chronic instabilities.

PURPOSE: The purpose of this study was to evaluate the clinical outcome after 1-stage reconstructions of the anterior and posterior cruciate ligaments (ACL, PCL) with reconstruction of the posterolateral corner (PLC) structures using autogenous hamstring grafts in chronic knee injuries. TYPE OF STUDY: Prospective case series. METHODS: We reviewed 17 patients (13 men and 4 women) with chronic multiligamentous injuries after a minimum follow-up of 2 years (range, 24 to 66.3 months). Arthroscopically assisted combined ACL/PCL reconstructions with autogenous semitendinosus-gracilis tendon grafts were performed using the single-incision endoscopic ACL technique and the single femoral tunnel, single-bundle transtibial tunnel PCL technique. The PLC was reconstructed with a free autogenous semitendinous tendon graft. The primary outcome measures were the International Knee Documentation Committee (IKDC) score and stress radiography. As secondary outcome measure, all patients were evaluated with a subjective questionnaire, physical examination, radiologic assessment, and KT-1000 arthrometer testing. RESULTS: The mean time from injury to the reconstructive procedure was 70.2 +/- 96.7 months (range, 5.1 to 312.6 months). At final IKDC evaluation, 4 patients (29.4%) were graded level B (nearly normal), 10 patients (58.8%) level C (abnormal), and 2 patients (11.8%) level D (grossly abnormal). The mean postoperative subjective IKDC score was 71.8 +/- 19.3 points. Mean posterior tibial displacement as measured through stress radiography at 90 degrees of knee flexion was reduced from -15.06 +/- 4.68 mm preoperatively to -7.12 +/- 3.37 mm postoperatively (P < .001). Mean anterior tibial displacement was 0.94 +/- 2.75 mm preoperatively compared with -1.59 +/- 3.50 mm postoperatively (P < .01). Three patients had a fixed posterior tibial subluxation (posterior tibial displacement < or = -3 mm on anterior stress radiographs) postoperatively. Severe subjective instability was reduced significantly by the operative procedure (P < .001). The mean postoperative total anterior-posterior side-to-side difference with the KT-1000 arthrometer testing was 2.00 +/- 2.23 mm (range, -4 to 7 mm). CONCLUSIONS: Combined chronic ACL/PCL/PLC instabilities can be successfully treated with 1-stage arthroscopic cruciate ligament reconstruction combined with PLC reconstruction using autogenous hamstring grafts. Although current reconstruction techniques are not able to restore normal tibiofemoral kinematics, most patients recover a functionally stable knee and have considerably improved knee function compared with their preoperative status, based on subjective parameters and objective criteria. LEVEL OF EVIDENCE: Level IV, case series, no historical or control group.

Adolescent↗

PubMed2005

Importance of femoral tunnel placement in double-bundle posterior cruciate ligament reconstruction: biomechanical analysis using a robotic/universal force-moment sensor testing system.

BACKGROUND: Previous studies have identified the femoral attachment of the posterior cruciate ligament fibers as one of the primary determinants of fiber tension behavior. In addition, a double-bundle posterior cruciate ligament reconstruction has been shown to restore the intact knee kinematics more closely than does a single-bundle reconstruction. HYPOTHESIS: An anterior tunnel position in double-bundle posterior cruciate ligament reconstruction restores the biomechanics of the normal knee more closely than does a posterior tunnel position. STUDY DESIGN: Controlled laboratory study. METHODS: Kinematics and in situ forces of human knees after double-bundle posterior cruciate ligament reconstruction with 2 different femoral tunnel positions (anterior vs posterior) were evaluated using a robotic/universal force-moment sensor testing system. Within the same specimen, the resulting knee kinematics and in situ forces were compared. For statistical analysis, 2-way analysis of variance repeated measures were performed. RESULTS: The femoral tunnel position of the double-bundle hamstring graft had significant effect on the resulting posterior tibial displacement and in situ forces of the hamstring grafts. The anterior femoral tunnel position provided significantly less posterior tibial translation than did the posterior tunnel position. There was a tendency toward higher in situ forces of grafts fixed in the anterior tunnel when compared to the posterior position, but this difference was statistically not significant. CONCLUSION: An anterior position of the bone tunnels in double-bundle posterior cruciate ligament reconstruction restores the normal knee kinematics more closely than does a posterior position of the tunnels. CLINICAL RELEVANCE: In double-bundle posterior cruciate ligament reconstruction, posterior placement of the tunnel should be avoided.

Aged↗

PubMed2005

Reliability of stress radiography for evaluation of posterior knee laxity.

BACKGROUND: Although stress radiography has been recommended for quantifying posterior tibial displacement in knees with posterior cruciate ligament insufficiency, the intratester reliability and intertester reliability of this measurement method have not been evaluated. HYPOTHESIS: Stress radiography is a reproducible measurement method in the assessment of posterior knee laxity in patients with posterior cruciate ligament lesions. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: Stress radiographs of 787 patients with suspected posterior cruciate ligament lesions taken using the Telos device were evaluated independently by 3 testers: 2 of the testers were clinically experienced in the evaluation of stress radiographs, and 1 tester was a novice tester. Change in mean, standard error of measurement with calculated confidence intervals, and intra-class correlation coefficients were determined to assess intratester and intertester reliability. RESULTS: There was no significant intratester change in mean. Intratester standard error of measurement was 1.03 mm; 95% confidence intervals were+/-2.02 mm for a single measurement and+/-2.86 mm for a change in measurement. The intratester intra-class correlation coefficient was 0.95. Intertester reliability revealed a significant change in mean between the experienced testers and the novice tester (P<.001). There was no substantial difference for the standard error of measurement of each tester. The mean intertester standard error of measurement was 1.41 mm; 95% confidence intervals were+/-2.77 mm for a single measurement and+/-3.91 mm for a change in measurement. The intertester intraclass correlation coefficient was 0.91. CONCLUSION: Stress radiography was found to be a measurement method with a useful reliability for evaluation of posterior laxity in patients with posterior cruciate ligament lesions. The reproducibility of stress radiography may be influenced by multiple variables, and standardized methods are needed to minimize measurement error.

Adolescent↗

PubMed2005

Development of a perforated biodegradable interference screw.

PURPOSE: The objective was to develop a perforated biodegradable interference screw to allow for enhanced osseous implant integration without impairing screw stability during insertion. TYPE OF STUDY: Mechanical testing, followed by animal study. METHODS: At first, manual perforation of 8 x 23-mm biodegradable poly-(L-co-D,L-lactide) interference screws was performed, using 3 different perforation patterns (clockwise spiral, counter-clockwise spiral, and parallel perforation), followed by torsional tests. Next, parallel perforated screws (n = 6) and unperforated control screws (n = 6) were applied to the proximal tibia of 12 sheep. The sheep were put down after 24 weeks and the screw site was examined histologically. Subsequently, molding of a parallel perforated screw followed by torsional tests was undertaken. RESULTS: The parallel perforated screw presented a torsional strength insignificantly different from the unperforated control screw and well beyond the reported maximum manual insertion torques of biodegradable interference screws in young human bone. When compared with the regular unperforated interference screw, the molded perforated screw exhibited a torsional strength of 91%, indicating a secure surgical application. In contrast to the unperforated screw, histologic evaluations revealed clear bone ingrowth into the perforations including the core of the perforated interference screw. CONCLUSIONS: Perforated, "cage-like" interference screws may be promising for the acceleration of osseous implant integration into the bone with a very low risk of screw breakage during insertion. CLINICAL RELEVANCE: To ameliorate osseous implant integration and possibly enhance ossification of former implant site in anterior cruciate ligament surgery.

Absorbable Implants↗

PubMed2003

Arthroscopic evaluation of articular cartilage lesions in posterior-cruciate-ligament-deficient knees.

PURPOSE: The goal of this study was to gain more information on the likelihood of developing cartilage lesions in posterior cruciate ligament (PCL)-deficient knees. TYPE OF STUDY: Retrospective clinical study. METHODS: Standardized arthroscopy records of 181 patients with a nonsurgically treated acute or chronic PCL injury were analyzed with respect to cartilage degeneration. Subgroups with different duration of PCL insufficiency, the influence of isolated PCL or combined PCL/posterolateral instability, and the grade of posterior laxity was analyzed. RESULTS: PCL insufficiency significantly increased the risk of developing medial femoral condyle and patellar cartilage degeneration over time. Of patients whose PCL deficiency was present for more than 5 years, 77.8% showed degenerative cartilage lesions of the medial femoral condyle and 46.7% showed cartilage degeneration of the patella. After 1 year of PCL insufficiency, the number of medial femoral cartilage lesions increased threefold (13.6% v 39.1%). With the presence of combined PCL/posterolateral insufficiency the amount of medial femoral degeneration was significantly increased (36.6% v 60.6%). CONCLUSIONS: We found that PCL insufficiency is not a benign injury with respect to the development of degenerative articular cartilage lesions. The early and continuous increase in cartilage degeneration at the medial femoral condyle and the patella should be considered when discussing operative versus conservative treatment for a PCL-deficient knee. The rapid development of medial arthritis should also be considered during decision making, particularly in patients with combined PCL/posterolateral instability or those who underwent previous partial medial menisectomy.

Adolescent↗

PubMedDate not supplied

Fixed posterior subluxation in posterior cruciate ligament-deficient knees: diagnosis and treatment of a new clinical sign.

Among 248 patients seen for posterior cruciate ligament insufficiency, 109 (44%) had fixed posterior subluxation of the tibia, defined as a condition in which posterior sag could not be reduced to a neutral position, as evidenced by posterior tibial displacement of 3 mm or more on anterior stress radiographs at 200 N. The mean fixed posterior displacement was 6.23 mm (range, 3 to 20). The fixed posterior subluxation was divided into three grades: I, 3 to 5 mm (57.8%); II, 6 to 10 mm (33.9%); and III, more than 10 mm (8.3%). Comparison of the 109 study patients with the 139 control patients revealed a history of a failed posterior cruciate ligament operation or of a patellar tendon harvest, male sex, and a long history of posterior cruciate ligament insufficiency as significant risk factors for the development of a fixed posterior subluxation. After patients were treated with a posterior tibial support brace, the fixed posterior subluxation could be reduced to a mean of 2.58 +/- 5.22 mm within an average treatment period of 180 days. Fixed posterior subluxation can be detected in patients with posterior cruciate ligament deficiency by anterior and posterior stress radiographs and should be addressed before posterior cruciate ligament reconstruction to prevent early overloading of the graft.

Adolescent↗