Padhraig F. O'Loughlin

Current Concepts in the Diagnosis and Treatment of Osteochondral Lesions of the Ankle

Osteochondral lesions of the ankle are a more common source of ankle pain than previously recognized. Although the exact pathophysiology of the condition has not been clearly established, it is likely that a variety of etiological factors play a role, with trauma, typically from ankle sprains, being the most common. Technological advancements in ankle arthroscopy and radiologic imaging, most importantly magnetic resonance imaging, have improved diagnostic capabilities for detecting osteochondral lesions of the ankle. Moreover, these technologies have allowed for the development of more sophisticated classification systems that may, in due course, direct specific future treatment strategies. Nonoperative treatment yields best results when employed in select pediatric and adolescent patients with osteochondritis dissecans. However, operative treatment, which is dependent on the size and site of the lesion, as well as the presence or absence of cartilage damage, is frequently warranted in both children and adults with osteochondral lesions. Arthroscopic microdrilling, micropicking, and open procedures, such as osteochondral autograft transfer system and matrix-induced autologous chondrocyte implantation, are frequently employed. The purpose of this article is to review the history, etiology, and classification systems for osteochondral lesions of the ankle, as well as to describe current approaches to diagnosis and management.

The Effect of Medial Versus Lateral Meniscectomy on the Stability of the Anterior Cruciate Ligament-Deficient Knee

Background: The pivot shift is a dynamic test of knee stability that involves a pathologic, multiplanar motion path elicited by a combination of axial load and valgus force during a knee flexion from an extended position. Purpose: To assess the stabilizing effect of the medial and lateral meniscus on anterior cruciate ligament-deficient (ACL-D) knees during the pivot shift examination. Study Design: Controlled laboratory study. Methods: A Lachman and a mechanized pivot shift test were performed on 16 fresh-frozen cadaveric hip-to-toe lower extremity specimens. The knee was tested intact, ACL-D, and after sectioning the medial meniscus (ACL/MM-D; n = 8), lateral meniscus (ACL/LM-D; n = 8), and both (ACL/LM/MM-D; n = 16). A navigation system recorded the resultant anterior tibial translations (ATTs). For statistical analysis an analysis of variance was used; significance was set at P < .05. Results: The ATT significantly increased in the ACL-D knee after lateral meniscectomy (ACL/LM-D; P < .05) during the pivot shift maneuver. In the lateral compartment of the knee, ATT in the ACL-D knee increased by 6 mm after lateral meniscectomy during the pivot shift (16.6 ± 6.0 vs 10.5 ± 3.5 mm, P < .01 for ACL/LM out vs ACL out). Medial meniscectomy, conversely, had no significant effect on ATT in the ACL-D knee during pivot shift examination (P > .05). With standardized Lachman examination, however, ATT significantly increased after medial but not lateral meniscectomy compared with the ACL-D knee (P < .001). Conclusion: Although the medial meniscus functions as a critical secondary stabilizer to anteriorly directed forces on the tibia during a Lachman examination, the lateral meniscus appears to be a more important restraint to anterior tibial translation during combined valgus and rotatory loads applied during a pivoting maneuver. Clinical Relevance: This model may have implications in the evaluation of surgical reconstruction procedures in complex knee injuries.

Robot-Assisted Unicompartmental Knee Arthroplasty

The outcomes of unicompartmental knee arthroplasties (UKAs) have demonstrated inconsistent long-term survival. We report the first clinical series of UKA using a semiactive robotic system for the implantation of an inlay unicondylar knee arthroplasty. Ten patients were selected for this study. Preoperative mechanical leg alignment values ranged from 0.3 degrees varus to 9.8 degrees varus. A haptic guidance system was used; a detailed description is given in the manuscript. The setup time for the robot was 41 minutes; intraoperative registration process, 7.5 minutes (6-13 minutes); skin incision, 8 cm; robot-assisted burring, 34.8 minutes (18-50 minutes); mean tourniquet time, 87.4 minutes (68-113 minutes); and overall operation time, 132 minutes (118-152 minutes). The planned and intraoperative tibiofemoral angle was within 1 degrees. The postoperative long leg axis radiographs were within 1.6 degrees. Haptic guidance in combination with a navigation module allows for precise planning and execution of both inlay components in UKA.

Selection and development of preclinical models in fracture-healing research.

Animal fracture models have been extensively applied to preclinical research as a platform to identify and characterize normal and abnormal physiological processes and to develop specific maneuvers that alter the biology and biomechanics being examined. The choice of animal model employed in a study bears a direct relationship to the specific intervention being analyzed. The animal models employed should be described clearly, control-group data should be established, and reproducibility should be defined from experiment to experiment and from institution to institution so that quantitative and qualitative outcomes can be reliably compared and contrasted to other related studies.

Effect of tibial tunnel position on stability of the knee after anterior cruciate ligament reconstruction: is the tibial tunnel position most important?

Background: Minimal attention has been directed toward tibial tunnel position and the native tibial anterior cruciate ligament (ACL) footprint. Purpose: To evaluate the effect of tibial tunnel position on restoration of knee kinematics and stability after ACL reconstruction. Study Design: Controlled laboratory study. Methods: Ten paired cadaveric knees were subjected to biomechanical testing (standardized Lachman and mechanized pivot-shift examination). With each maneuver, a computer-assisted navigation system recorded the 3-dimensional motion path of a tracked point at the center of the tibia, medial tibial plateau, and lateral tibial plateau. The testing protocol consisted of evaluation in the intact state and after complete ACL transection, after ACL transection with bilateral meniscectomy, and after ACL reconstruction using 3 tibial tunnel positions—over the top (OTT), anterior footprint (AT), and posterior footprint (PT)—with a standard femoral socket placed in the center of the femoral footprint. Repeated-measures analysis of variance with a post hoc Tukey test compared measured translations with each condition. Results: A significant difference in anterior translation was seen with Lachman examination between the ACL-deficient condition and both the OTT and AT reconstructions, but no significant difference was observed between the ACL-deficient and PT reconstruction. The OTT and AT constructs were significantly better in limiting anterior translation of the lateral compartment compared with the PT ACL reconstruction during a pivot-shift maneuver in the ACL- and meniscal-deficient knee. However, anteriorizing the tibial position was accompanied by a correspondingly greater risk and magnitude of graft impingement in extension. Clinical Relevance: The OTT and anterior tibial tunnel positions better control the Lachman and the pivot shift compared with an ACL graft placed in the posterior aspect of the tibial footprint. However, an anterior tibial tunnel position must be balanced against an increased risk and magnitude of graft impingement in extension.

A Comparison of the Effect of Central Anatomical Single-Bundle Anterior Cruciate Ligament Reconstruction and Double-Bundle Anterior Cruciate Ligament Reconstruction on Pivot-Shift Kinematics

Background: Biomechanical differences between anatomical double-bundle and central single-bundle anterior cruciate ligament reconstruction using the same graft tissue have not been defined. Purpose: The purpose of this study was to compare these reconstructions in their ability to restore native knee kinematics during a reproducible Lachman and pivot-shift examination. Study Design: Controlled laboratory study. Methods: Using a computer-assisted navigation system, 10 paired knees were subjected to biomechanical testing with a standardized Lachman and mechanized pivot-shift examination. The navigation system recorded the 3D motion path of a tracked point at the center of the tibia, center of the medial tibial plateau, and center of the lateral tibial plateau with each maneuver. The testing protocol consisted of evaluation in the intact state, after complete anterior cruciate ligament transection, after medial and lateral meniscectomy, and after anterior cruciate ligament reconstruction with (1) a single-bundle center-center or (2) anatomical double-bundle technique. Repeated-measures analysis of variance with a post hoc Tukey test was used to compare the measured translations with each test condition. Results: A significant difference in anterior translation was seen with Lachman examination between the anterior cruciate ligament– and medial and lateral meniscus–deficient condition compared with both the double-bundle and single-bundle center-center anterior cruciate ligament reconstruction (P < .001); no significant difference was observed between reconstructions. The double-bundle construct was significantly better in limiting anterior translation of the lateral compartment compared with the single-bundle reconstruction during a pivot-shift maneuver (2.0 ± 5.7 mm vs 7.8 ± 1.8 mm, P < .001) and was not significantly different than the intact anterior cruciate ligament condition (2.7 mm ± 4.7 mm, P > .05). Discussion: Although double-bundle and single-bundle, center-center anterior cruciate ligament reconstructions appear equally effective in controlling anterior translation during a Lachman examination, analysis of pivot-shift kinematics reveals significant differences between these surgical reconstructions. An altered rotational axis resulted in significantly greater translation of the lateral compartment in the single-bundle compared with double-bundle reconstruction. Clinical Relevance: A double-bundle anterior cruciate ligament reconstruction may be a favorable construct for restoration of knee kinematics in the at-risk knee with associated meniscal injuries and/or significant pivot shift on preoperative examination.

Effect of Single-Bundle and Double-Bundle Anterior Cruciate Ligament Reconstructions on Pivot-Shift Kinematics in Anterior Cruciate Ligament– and Meniscus-Deficient Knees

Background: Recent laboratory and clinical studies report no difference between single-bundle (SB) and double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. Hypothesis: Anatomical DB ACL reconstruction would restore knee kinematics in a complex injury model of ACL–meniscus injury closer to the intact state when compared with 2 common SB ACL reconstructions. Study Design: Controlled laboratory study. Methods: Five fresh-frozen cadaveric hip-to-toe lower extremity specimens were used for this study (10 knees). A surgical navigation system recorded the 3-dimensional motion path of a tracked point at the center of the medial and lateral compartments during a 68-N Lachman test and a mechanized pivot-shift test. Testing was performed on the intact knee, after ACL, medial meniscus, and lateral meniscus resection and after 3 ACL reconstructions: anatomical anteromedial SB, nonanatomical SB (posterolateral tibia to anteromedial femur), and anatomical DB. Same-sized hamstring grafts were used for all reconstructions. Repeated-measures analysis of variance with a post hoc Tukey multiple-comparison test was used to compare the anterior tibial translations of the 3 grafts during laxity testing. Results: Regarding the Lachman test, there was no difference between the anatomical anteromedial SB and DB reconstructions. For the mechanized pivot shift, anatomical DB reconstruction restored anterior tibial translation to the intact state; however, significantly greater anterior tibial translation was detected after anatomical anteromedial SB and nonanatomical SB reconstruction, compared with the intact knee. In addition, there was no difference in medial compartment translations during the pivot shift between the intact and reconstructed states. Conclusion: Anatomical DB ACL reconstruction was able to restore intact knee kinematics during the pivot shift even in the severe injury model. Clinical Relevance: Double-bundle ACL reconstruction procedures may be preferred in cases of high-grade instability or meniscus deficiency.

Ankle Instability in Sports

Abstract Ankle stability is integral to normal motion and to minimizing the risk of ankle sprain during participation in sport activities. The ability of the dynamic and static stabilizers of the ankle joint to maintain their structural integrity is a major component of the normal gait cycle. In sports, this quality assumes even greater importance given the range of movement and stresses imposed on the ankle during various sporting disciplines. In the general population, the incidence of ankle sprain is very high. In several studies, injuries to the lateral ankle ligaments have been shown to be the most common sports-related injuries, accounting for approximately 25% of all sports-related injuries. Furthermore, up to 80% of all ankle sprains involve the lateral ligament complex. Other studies have estimated their incidence as approximately 5000 injuries per day in the United Kingdom and 23 000 in the United States. Aggressive treatment of the sprained ankle is essential to maintain foot and ankle mobility and prevent prolonged disability and subsequent overuse injuries among athletes, both professional and “weekend warriors” alike.

Effect of Tunnel Position and Graft Size in Single-Bundle Anterior Cruciate Ligament Reconstruction: An Evaluation of Time-Zero Knee Stability

PURPOSE To determine whether (1) increased graft size with anatomic anterior cruciate ligament reconstruction (ACLR) would confer proportionally increased time-zero biomechanical stability and (2) larger grafts would compensate for the inferior time-zero biomechanical kinematics of nonanatomic, single-bundle ACLR. METHODS Ten cadaveric knees were allocated for single-bundle ACLR in an anatomic, center-center or nonanatomic, posterolateral-to-anteromedial footprint position with hamstring autograft. Medial arthrotomy defined the native anterior cruciate ligament (ACL) tibial and femoral footprints. ACLR was performed with a 6-mm semitendinosus graft in 6-mm tunnels and repeated with a 9-mm semitendinosus and gracilis graft in 9-mm tunnels for each knee. Lachman and instrumented pivot-shift examinations assessed knee stability in the ACL-intact, ACL-deficient, and ACLR conditions. Medial and lateral meniscectomies after ACL transection created reproducible pivot shifts. Significance was defined as P < .05. RESULTS ACLR in the center-center or posterolateral-to-anteromedial position significantly reduced anterior tibial translation compared with the ACL- and meniscus-deficient conditions (P < .001). Larger graft size, however, did not significantly improve time-zero biomechanical stability compared with a smaller graft in the same position for either reconstruction (P = .41 to .74). A center-center ACLR controlled tibial translation significantly better than a nonanatomic graft position regardless of graft size (P < .001). A smaller graft in the anatomic position controlled tibial translation significantly better than a larger graft in a nonanatomic position (P < .001). CONCLUSIONS This study showed that increasing graft size did not improve the time-zero biomechanical stability of the knee after ACLR. Increased graft size did not compensate for the biomechanical instability documented with the nonanatomic tunnel position. Restoration of native footprint anatomy in ACLR is of paramount importance regardless of graft size and source. CLINICAL RELEVANCE A larger graft size does not ameliorate the inferior time-zero biomechanics associated with nonanatomic tunnel preparation during single-bundle ACLR.

Lateral Ligament Repair and Reconstruction Restore Neither Contact Mechanics of the Ankle Joint nor Motion Patterns of the Hindfoot

BACKGROUND Ankle sprains may damage both the lateral ligaments of the hindfoot and the osteochondral tissue of the ankle joint. When nonoperative treatment fails, operative approaches are indicated to restore both native motion patterns at the hindfoot and ankle joint contact mechanics. The goal of the present study was to determine the effect of lateral ligament injury, repair, and reconstruction on ankle joint contact mechanics and hindfoot motion patterns. METHODS Eight cadaveric specimens were tested with use of robotic technology to apply combined compressive (200-N) and inversion (4.5-Nm) loads to the hindfoot at 0° and 20° of plantar flexion. Contact mechanics at the ankle joint were simultaneously measured. A repeated-measures experiment was designed with use of the intact condition as control, with the other conditions including sectioned anterior talofibular and calcaneofibular ligaments, the Broström and Broström-Gould repairs, and graft reconstruction. RESULTS Ligament sectioning decreased contact area and caused a medial and anterior shift in the center of pressure with inversion loads relative to those with the intact condition. There were no significant differences in inversion or coupled axial rotation with inversion between the Broström repair and the intact condition; however, medial translation of the center of pressure remained elevated after the Broström repair relative to the intact condition. The Gould modification of the Broström procedure provided additional support to the hindfoot relative to the Broström repair, reducing inversion and axial rotation with inversion beyond that of intact ligaments. There were no significant differences in center-of-pressure excursion patterns between the Broström-Gould repair and the intact ligament condition, but this repair increased contact area beyond that with the ligaments intact. Graft reconstruction more closely restored inversion motion than did the Broström-Gould repair at 20° of plantar flexion but limited coupled axial rotation. Graft reconstruction also increased contact areas beyond the lateral ligament-deficient conditions but altered center-of-pressure excursion patterns relative to the intact condition. CONCLUSIONS No lateral ankle ligament reconstruction completely restored native contact mechanics of the ankle joint and hindfoot motion patterns.