Craig S. Mauro

Biomechanical consequences of a tear of the posterior root of the medial meniscus. Surgical technique.

BACKGROUND Tears of the posterior root of the medial meniscus are becoming increasingly recognized. They can cause rapidly progressive arthritis, yet their biomechanical effects are not understood. The goal of this study was to determine the effects of posterior root tears of the medial meniscus and their repairs on tibiofemoral joint contact pressure and kinematics. METHODS Nine fresh-frozen cadaver knees were used. An axial load of 1000 N was applied with a custom testing jig at each of four knee-flexion angles: 0 degrees , 30 degrees , 60 degrees , and 90 degrees . The knees were otherwise unconstrained. Four conditions were tested: (1) intact, (2) a posterior root tear of the medial meniscus, (3) a repaired posterior root tear, and (4) a total medial meniscectomy. Fuji pressure-sensitive film was used to record the contact pressure and area for each testing condition. Kinematic data were obtained by using a robotic arm to record the position of the knees for each loading condition. Three-dimensional knee kinematics were analyzed with custom programs with use of previously described transformations. The measured variables were axial rotation, varus angulation, lateral translation, and anterior translation. RESULTS In the medial compartment, a posterior root tear of the medial meniscus caused a 25% increase in peak contact pressure compared with that found in the intact condition (p < 0.001). Repair restored the peak contact pressure to normal. No difference was detected between the peak contact pressure after the total medial meniscectomy and that associated with the root tear. The peak contact pressure in the lateral compartment after the total medial meniscectomy was up to 13% greater than that for all other conditions (p = 0.026). Significant increases in external rotation and lateral tibial translation, compared with the values in the intact knee, were observed in association with the posterior root tear (2.98 degrees and 0.84 mm, respectively) and the meniscectomy (4.45 degrees and 0.80 mm, respectively), and these increases were corrected by the repair. CONCLUSIONS This study demonstrated significant changes in contact pressure and knee joint kinematics due to a posterior root tear of the medial meniscus. Root repair was successful in restoring joint biomechanics to within normal conditions.

Stress radiography for quantifying posterior cruciate ligament deficiency

PURPOSE The objective of this study was to evaluate the efficacy of different stress radiography techniques in quantifying a posterior cruciate ligament (PCL) lesion. TYPE OF STUDY Prospective serial study. METHODS Sixty patients with subacute or chronic PCL injuries, confirmed using magnetic resonance imaging (MRI) or arthroscopic evaluation, were enrolled in this study. The patients underwent a KT-2000 (Medmetric, San Diego, CA) examination and a series of stress radiographs that included a radiographic posterior drawer test with Telos (Telos, Weterstadt, Germany) at 90 degrees and 25 degrees of knee flexion, an active radiograph at 90 degrees of knee flexion, and an axial view radiograph. RESULTS Stress radiography performed with Telos showed an average posterior tibial displacement of 11.54 +/- 4.93 mm and 7.97 +/- 3.16 mm at 90 degrees and 25 degrees, respectively. The active radiographs showed an average posterior tibial displacement of 11.48 +/- 5.14 mm. CONCLUSIONS Stress radiographs were shown to be superior to arthrometric evaluation in quantifying posterior tibial translation. The techniques performed with the knee at 90 degrees of knee flexion allowed for greater posterior tibial displacement and, consequently, an easier quantification of the degree of ligament insufficiency. Stress radiographs performed through hamstring contraction gave the same results as those performed with Telos at 90 degrees of knee flexion.

Posterior Cruciate Ligament Anatomy, Biomechanics, and Outcomes

The optimal treatment of posterior cruciate ligament ruptures remains controversial despite numerous recent basic science advances on the topic. The current literature on the anatomy, biomechanics, and clinical outcomes of posterior cruciate ligament reconstruction is reviewed. Recent studies have quantified the anatomic location and biomechanical contribution of each of the 2 posterior cruciate ligament bundles on tunnel placement and knee kinematics during reconstruction. Additional laboratory and cadaveric studies have suggested double-bundle reconstructions of the posterior cruciate ligament may better restore normal knee kinematics than single-bundle reconstructions although clinical outcomes have not revealed such a difference. Tibial inlay posterior cruciate ligament reconstructions (either open or arthroscopic) are preferred by many authors to avoid the “killer turn” and graft laxity with cyclic loading. Posterior cruciate ligament reconstruction improves subjective patient outcomes and return to sport although stability and knee kinematics may not return to normal.

Biomechanical comparison of tibial inlay versus transtibial techniques for posterior cruciate ligament reconstruction: analysis of knee kinematics and graft in situ forces.

Background The tibial inlay technique for posterior cruciate ligament reconstruction has been proposed to provide a more anatomic reconstruction because it eliminates the sharp turn in the graft as it exits the proximal margin of the tibial tunnel in the transtibial technique. Hypothesis Reconstruction of the posterior cruciate ligament using the tibial inlay technique would more closely restore intact knee kinematics and in situ forces in the posterior cruciate ligament than would reconstruction using the transtibial technique. Methods Ten human cadaveric knees were tested in a controlled laboratory study. A robotic/universal force-moment sensor testing system was used to apply a 134-N posterior tibial load at 5 knee flexion angles: 0°, 30°, 60°, 90°, and 120°. Four knee conditions were tested: intact, posterior cruciate ligament–deficient, and the single-bundle tibial inlay reconstruction and transtibial posterior cruciate ligament reconstruction. Results Both reconstruction techniques restored posterior tibial translations to 1.7 to 2.1 mm of the intact knee, with no statistical differences between the techniques. In response to the posterior tibial load, in situ forces in both grafts were between 7 and 39 N less than those in the intact posterior cruciate ligament, with no significant differences between the grafts. Clinical Relevance The study suggests that either technique may be performed with similar biomechanical results at initial fixation under these loading conditions.

The role of the tibial slope in sustaining and treating anterior cruciate ligament injuries

PurposeA steep tibial slope may contribute to anterior cruciate ligament (ACL)-injuries, a higher degree of instability in the case of ACL insufficiency, and recurrent instability after ACL reconstruction. A better understanding of the significance of the tibial slope could improve the development of ACL injury screening and prevention programmes, might serve as a basis for individually adapted rehabilitation programmes after ACL reconstruction and could clarify the role of slope-decreasing osteotomies in the treatment of ACL insufficiency. This article summarizes and discusses the current published literature on these topics.MethodsA comprehensive review of the MEDLINE database was carried out to identify relevant articles using multiple different keywords (e.g. ‘tibial slope’, ‘anterior cruciate ligament’, ‘osteotomy’, and ‘knee instability’). The reference lists of the reviewed articles were searched for additional relevant articles.ResultsIn cadaveric studies, an artificially increased tibial slope produced an anterior shift of the tibia relative to the femur. While mathematical models additionally demonstrated increased strain in the ACL, cadaveric studies have not confirmed these findings. There is some evidence that a steep tibial slope represents a risk factor for non-contact ACL injuries. MRI-based studies indicate that a steep slope of the lateral tibial plateau might specifically be responsible for this injury mechanism. The influence of the tibial slope on outcomes after ACL reconstruction and the role of slope-decreasing osteotomies in the treatment of ACL insufficiency remain unclear.ConclusionThe role of the tibial slope in sustaining and treating ACL injuries is not well understood. Characterizing the tibial plateau surface with a single slope measurement represents an insufficient approximation of its three-dimensionality, and the biomechanical impact of the tibial slope likely is more complex than previously appreciated.Level of evidenceIV.

Loss of Extension Following Anterior Cruciate Ligament Reconstruction: Analysis of Incidence and Etiology Using IKDC Criteria

PURPOSE The purpose of this study was to determine the incidence of and factors associated with loss of extension (LOE) 4 weeks after anterior cruciate ligament (ACL) reconstruction using the new IKDC Knee Ligament Evaluation Form criteria for loss of motion. METHODS A retrospective review of patients who had undergone arthroscopic ACL reconstruction between 1995 and 2000 was performed. An endoscopic single tunnel technique with autograft or allograft was used in all cases. A standardized physical therapy program was prescribed to all patients. Subjects with revision ACL reconstruction, concomitant ligament surgery, meniscal transplantation, or any articular cartilage surgery were excluded. LOE was defined as greater than a 5 degrees side-to-side difference in passive knee extension 4 weeks after surgery, the need for repeat arthroscopy to restore extension, or use of a drop-out cast to restore extension. RESULTS Fifty-eight of 229 (25.3%) patients developed LOE 4 weeks after ACL reconstruction. LOE was not associated with age, sex, presence of nerve block, concomitant meniscal procedures, specific graft type, or tourniquet time (P > .05). LOE was significantly associated with preoperative extension, time from injury to surgery, and use of autograft (P < .05). Twenty-eight (12.2%) patients underwent an arthroscopic procedure to recover loss of motion. Following arthroscopy, 4 (1.7%) patients had passive motion deficits between 6 degrees and 10 degrees , with none greater than 10 degrees . CONCLUSIONS Preoperative range of motion and time to surgery are intimately related to a patients postoperative extension. While 48% of patients that lacked full extension by 4 weeks eventually required arthroscopic debridement to achieve satisfactory extension, our treatment algorithm led to an overall incidence of LOE greater than 5 degrees at final follow-up of 1.7%. LEVEL OF EVIDENCE Level III, therapeutic, retrospective, comparative study.

Abnormal tibiofemoral contact stress and its association with altered kinematics after center-center anterior cruciate ligament reconstruction: an in vitro study.

Background: Abnormal tibiofemoral contact stress and aberrant kinematics may influence the progression of osteoarthritis in the anterior cruciate ligament (ACL)–deficient and the ACL-reconstructed knee. However, relationships between contact stress and kinematics after ACL reconstruction are poorly understood. Therefore, we posed the following research questions: (1) How do ACL deficiency and reconstruction affect the kinematics of and contact stress in the tibiofemoral joint? (2) What kinematic differences are associated with abnormal contact stress after ACL reconstruction? Hypothesis: Center-center ACL reconstruction will not restore knee kinematics and contact stress. Correlations will exist between abnormal contact stress and aberrant kinematics after ACL reconstruction. Study Design: Controlled laboratory study. Methods: Clinical tests of anterior and rotational stability were simulated on 11 cadaveric knees using an industrial robot. Tests were conducted with the ACL intact, sectioned, and after single-bundle ACL reconstruction using a quadrupled hamstring autograft with tunnels drilled through the center of the native footprints. Kinematics were recorded during the tests. Contact stress was continuously recorded from a stress transducer fixed to the tibial plateau, and mean contact stress was calculated regionally. Results: ACL deficiency resulted in increased mean contact stress in the posterior sectors of the medial and lateral compartments under anterior and rotational loads, respectively. Reconstruction reduced stress in these locations; however, contact stress abnormalities remained. On average, kinematics were overconstrained after ACL reconstruction (≤1.8 mm and ≤2.6° in all directions). However, combinations of overconstrained and underconstrained motions in abduction/adduction and medial-lateral translation in response to combined moments, and anterior-posterior translation, medial-lateral translation, and axial rotation in response to an anterior load were associated with abnormal mean contact stress. Conclusion: ACL reconstruction reduces high stresses generated in the posterior compartment of the ACL-deficient knee. Abnormal contact stress after ACL reconstruction is related to multiplanar variations in knee kinematics. Clinical Relevance: Clinical measures of multiplanar kinematics may help to better characterize the quality of ACL reconstruction. Such measures may help identify patients at increased risk of long-term joint degeneration following this surgery.

Abnormal Tibiofemoral Contact Stress and Its Association With Altered Kinematics After Center-Center Anterior Cruciate Ligament Reconstruction

Background: Abnormal tibiofemoral contact stress and aberrant kinematics may influence the progression of osteoarthritis in the anterior cruciate ligament (ACL)–deficient and the ACL-reconstructed knee. However, relationships between contact stress and kinematics after ACL reconstruction are poorly understood. Therefore, we posed the following research questions: (1) How do ACL deficiency and reconstruction affect the kinematics of and contact stress in the tibiofemoral joint? (2) What kinematic differences are associated with abnormal contact stress after ACL reconstruction? Hypothesis: Center-center ACL reconstruction will not restore knee kinematics and contact stress. Correlations will exist between abnormal contact stress and aberrant kinematics after ACL reconstruction. Study Design: Controlled laboratory study. Methods: Clinical tests of anterior and rotational stability were simulated on 11 cadaveric knees using an industrial robot. Tests were conducted with the ACL intact, sectioned, and after single-bundle ACL reconstruction using a quadrupled hamstring autograft with tunnels drilled through the center of the native footprints. Kinematics were recorded during the tests. Contact stress was continuously recorded from a stress transducer fixed to the tibial plateau, and mean contact stress was calculated regionally. Results: ACL deficiency resulted in increased mean contact stress in the posterior sectors of the medial and lateral compartments under anterior and rotational loads, respectively. Reconstruction reduced stress in these locations; however, contact stress abnormalities remained. On average, kinematics were overconstrained after ACL reconstruction (≤1.8 mm and ≤2.6° in all directions). However, combinations of overconstrained and underconstrained motions in abduction/adduction and medial-lateral translation in response to combined moments, and anterior-posterior translation, medial-lateral translation, and axial rotation in response to an anterior load were associated with abnormal mean contact stress. Conclusion: ACL reconstruction reduces high stresses generated in the posterior compartment of the ACL-deficient knee. Abnormal contact stress after ACL reconstruction is related to multiplanar variations in knee kinematics. Clinical Relevance: Clinical measures of multiplanar kinematics may help to better characterize the quality of ACL reconstruction. Such measures may help identify patients at increased risk of long-term joint degeneration following this surgery.

The Recognition and Evaluation of Patterns of Compensatory Injury in Patients With Mechanical Hip Pain

Context: In active individuals with femoroacetabular impingement (FAI), the resultant reduction in functional range of motion leads to high impaction loads at terminal ranges. These increased forces result in compensatory effects on bony and soft tissue structures within the hip joint and hemipelvis. An algorithm is useful in evaluating athletes with pre-arthritic, mechanical hip pain and associated compensatory disorders. Evidence Acquisition: A literature search was performed by a review of PubMed articles published from 1976 to 2013. Level of Evidence: Level 4. Results: Increased stresses across the bony hemipelvis result when athletes with FAI attempt to achieve supraphysiologic, terminal ranges of motion (ROM) through the hip joint required for athletic competition. This can manifest as pain within the pubic joint (osteitis pubis), sacroiliac joint, and lumbosacral spine. Subclinical posterior hip instability may result when attempts to increase hip flexion and internal rotation are not compensated for by increased motion through the hemipelvis. Prominence of the anterior inferior iliac spine (AIIS) at the level of the acetabular rim can result in impingement of the anterior hip joint capsule or iliocapsularis muscle origin against the femoral head-neck junction, resulting in a distinct form of mechanical hip impingement (AIIS subspine impingement). Iliopsoas impingement (IPI) has also been described as an etiology for anterior hip pain. IPI results in a typical 3-o’clock labral tear as well as an inflamed capsule in close proximity to the overlying iliopsoas tendon. Injury in athletic pubalgia occurs during high-energy twisting activities in which abnormal hip ROM and resultant pelvic motion lead to shearing across the pubic symphysis. Conclusion: Failure to recognize and address concomitant compensatory injury patterns associated with intra-articular hip pathology can result in significant disability and persistent symptoms in athletes with pre-arthritic, mechanical hip pain. Strength-of-Recommendation Taxonomy (SORT): B

Practice patterns for subacromial decompression and rotator cuff repair: An analysis of the American Board of Orthopaedic Surgery database

BACKGROUND Recently there have been several evolving trends in the practice of shoulder surgery. Arthroscopic subacromial decompression has been performed with greater frequency by orthopaedic surgeons, and there has been considerable recent interest in arthroscopic rotator cuff repair. The purpose of this study was to identify trends in practice patterns for subacromial decompression and rotator cuff repair over time and in relation to the location of practice, fellowship training, and declared subspecialty of the surgeon. METHODS We reviewed the American Board of Orthopaedic Surgery Part II database to identify patterns in the utilization of open and arthroscopic subacromial decompression and rotator cuff repair among candidates for board certification. All procedures involving only arthroscopic or open subacromial decompression and/or rotator cuff repair from 2004 to 2009 were identified. The rates of arthroscopic and open subacromial decompression and/or rotator cuff repair were compared in terms of year, geographic region, fellowship training, and declared subspecialty of the surgeon. RESULTS Between 2004 and 2009, 12,136 surgical procedures involving only arthroscopic or open subacromial decompression and/or rotator cuff repair were performed. There were significant differences in treatment with respect to year, geographic region of practice, declared subspecialty, and fellowship training (p < 0.001). There was a significant increase over time in the utilization of arthroscopy among all candidates (p < 0.001). Surgeons with sports medicine fellowship training or a sports-medicine-declared subspecialty performed significantly more subacromial decompressions and rotator cuff repairs arthroscopically than all other candidates (p < 0.001). During this time period, there was a significant decrease in the rate of arthroscopic subacromial decompression, both as an isolated procedure and combined with arthroscopic rotator cuff repair (p < 0.001). CONCLUSIONS From 2004 to 2009, there was a significant shift throughout the United States toward arthroscopic rotator cuff repair and subacromial decompression among young orthopaedic surgeons, with sports medicine fellowship-trained surgeons performing more of their procedures arthroscopically than surgeons with other training. However, there was an increasing frequency of arthroscopic rotator cuff repair performed without subacromial decompression, and, overall, there was a decrease in the frequency of isolated arthroscopic subacromial decompression over time.