Ermias S. Abebe

Femoral Tunnel Placement During Anterior Cruciate Ligament Reconstruction: An In Vivo Imaging Analysis Comparing Transtibial and 2-Incision Tibial Tunnel–Independent Techniques

Background Recent studies have questioned the ability of the transtibial technique to place the anterior cruciate ligament graft within the footprint of the anterior cruciate ligament on the femur. There are limited data directly comparing the abilities of transtibial and tibial tunnel—independent techniques to place the graft anatomically at the femoral attachment site of the anterior cruciate ligament in patients. Hypothesis Because placement with the tibial tunnel–independent technique is unconstrained by the tibial tunnel, it would allow for more anatomic tunnel placement compared with the transtibial technique. Study Design Cross-sectional study; Level of evidence, 3. Methods High-resolution, multiplanar magnetic resonance imaging and advanced 3-dimensional modeling techniques were used to measure in vivo femoral tunnel placement in 8 patients with the transtibial technique and 8 patients with a tibial tunnel–independent technique. Femoral tunnel placement in 3 dimensions was measured relative to the center of the native anterior cruciate ligament attachment on the intact contralateral knee. Results The tibial tunnel–independent technique placed the graft closer to the center of the native anterior cruciate ligament attachment compared with the transtibial technique. The transtibial technique placed the tunnel center an average of 9 mm from the center of the anterior cruciate ligament attachment, compared with 3 mm for the tibial tunnel–independent technique. The transtibial technique resulted in a more anterior and superior placement of the tunnel compared with the tibial tunnel– independent technique. Conclusion The tibial tunnel–independent technique allowed for more anatomic femoral tunnel placement compared with the transtibial technique.

The effects of femoral graft placement on in vivo knee kinematics after anterior cruciate ligament reconstruction

Achieving anatomical graft placement remains a concern in Anterior Cruciate Ligament (ACL) reconstruction. The purpose of this study was to quantify the effect of femoral graft placement on the ability of ACL reconstruction to restore normal knee kinematics under in vivo loading conditions. Two different groups of patients were studied: one in which the femoral tunnel was placed near the anterior and proximal border of the ACL (anteroproximal group, n=12) and another where the femoral tunnel was placed near the center of the ACL (anatomic group, n=10) MR imaging and biplanar fluoroscopy were used to measure in vivo kinematics in these patients during a quasi-static lunge. Patients with anteroproximal graft placement had up to 3.4mm more anterior tibial translation, 1.1mm more medial tibial translation and 3.7° more internal tibial rotation compared to the contralateral side. Patients with anatomic graft placement had motion that more closely replicated that of the intact knee, with anterior tibial translation within 0.8mm, medial tibial translation within 0.5mm, and internal tibial rotation within 1°. Grafts placed anteroproximally on the femur likely provide insufficient restraint to these motions due to a more vertical orientation. Anatomical femoral placement of the graft is more likely to reproduce normal ACL orientation, resulting in a more stable knee. Therefore, achieving anatomical graft placement on the femur is crucial to restoring normal knee function and may decrease the rates of joint degeneration after ACL reconstruction.

The effect of femoral tunnel placement on ACL graft orientation and length during in vivo knee flexion

Anatomically placed grafts are believed to more closely restore the function of the ACL. This study measured the effect of femoral tunnel placement on graft orientation and length during weight-bearing flexion. Both knees of twelve patients where the graft was placed near the anteroproximal border of the ACL and ten where the graft was placed near the center of the ACL were imaged using MR. These images were used to create 3D models of the reconstructed and intact contralateral knees, including the attachment sites of the native ACL and graft. Next, patients were imaged using biplanar fluoroscopy while performing a quasi-static lunge. The models were registered to the fluoroscopic images to reproduce in vivo knee motion. From the relative motion of the attachment sites on the models, the length and orientation of the graft and native ACL were measured. Grafts placed anteroproximally on the femur were longer and more vertical than the native ACL in both the sagittal and coronal planes, while anatomically placed grafts more closely mimicked ACL motion. In full extension, the grafts placed anteroproximally were 12.3±5.2° (mean and 95%CI) more vertical than the native ACL in the sagittal plane, whereas the grafts placed anatomically were 2.9±3.7° less vertical. Grafts placed anteroproximally were up to 6±2 mm longer than the native ACL, while the anatomically placed grafts were a maximum of 2±2 mm longer. In conclusion, grafts placed anatomically more closely restored native ACL length and orientation. As a result, anatomic grafts are more likely to restore intact knee kinematics.

The effects of femoral graft placement on cartilage thickness after anterior cruciate ligament reconstruction

Altered joint motion has been thought to be a contributing factor in the long-term development of osteoarthritis after ACL reconstruction. While many studies have quantified knee kinematics after ACL injury and reconstruction, there is limited in vivo data characterizing the effects of altered knee motion on cartilage thickness distributions. Thus, the objective of this study was to compare cartilage thickness distributions in two groups of patients with ACL reconstruction: one group in which subjects received a non-anatomic reconstruction that resulted in abnormal joint motion and another group in which subjects received an anatomically placed graft that more closely restored normal knee motion. Ten patients with anatomic graft placement (mean follow-up: 20 months) and 12 patients with non-anatomic graft placement (mean follow-up: 18 months) were scanned using high-resolution MR imaging. These images were used to generate 3D mesh models of both knees of each patient. The operative and contralateral knee models were registered to each other and a grid sampling system was used to make site-specific comparisons of cartilage thickness. Patients in the non-anatomic graft placement group demonstrated a significant decrease in cartilage thickness along the medial intercondylar notch in the operative knee relative to the intact knee (8%). In the anatomic graft placement group, no significant changes were observed. These findings suggest that restoring normal knee motion after ACL injury may help to slow the progression of degeneration. Therefore, graft placement may have important implications on the development of osteoarthritis after ACL reconstruction.

Altered Tibiofemoral Kinematics in the Affected Knee and Compensatory Changes in the Contralateral Knee After Anterior Cruciate Ligament Reconstruction

Background: Previous studies of knee kinematics after anterior cruciate ligament (ACL) reconstruction have generally employed low-effort tasks and typically not assessed changes in kinematics over time. Hypotheses: (1) During single-legged hop landing, ACL-reconstructed limbs will have altered kinematics compared with contralateral (ACL-intact) limbs 5 months after surgery. (2) Kinematic differences between limbs will decrease over time because of changes in both ACL-reconstructed and ACL-intact limbs. Study Design: Controlled laboratory study. Methods: In vivo kinematics of ACL-reconstructed and contralateral ACL-intact knees were evaluated for 14 subjects during single-legged forward-hop landings at 5 and 12 months after surgery on the basis of dynamic stereo x-ray imaging. Differences between limbs and changes over time were assessed via repeated-measures analysis of variance. Results: Five months after surgery, ACL-reconstructed knees landed significantly less flexed compared with contralateral ACL-intact knees (20.9° vs 28.4°, respectively; P < .05). The ACL-reconstructed knees were significantly more externally rotated (12.2° vs 6.5°; P < .05) and medially translated (3.8 vs 2.3 mm; P < .009) compared with ACL-intact knees. Anterior-posterior translation was similar between limbs. From 5 to 12 months, knee flexion at landing increased in ACL-reconstructed knees (mean change, +3.4°; P < .05) and decreased in contralateral knees (mean change, –3.3°; P < .05). External tibial rotation also significantly decreased in ACL-reconstructed knees (–2.2°; P < .05) and increased in contralateral knees (+1.1°; P = .117) over time. Medial tibial translation decreased slightly over time only in ACL-reconstructed knees (–0.3 mm). Conclusion: Five months after ACL reconstruction, landing kinematics differed between ACL-reconstructed and contralateral ACL-intact knees during a dynamic high-loading activity. These differences decreased over time, owing to changes in both the ACL-reconstructed and contralateral ACL-intact limbs. Clinical Relevance: This study identified kinematic changes over time in both the ACL-injured and contralateral ACL-intact knees after ACL reconstruction. These kinematic adaptations could have important implications for postoperative care, including evaluating the optimal timing of return to sports and the development of bilateral neuromuscular rehabilitation programs that may improve patient outcomes and reduce reinjuries in both the short and long terms.

The Effects of Anterior Cruciate Ligament Deficiency on the Meniscus and Articular Cartilage A Novel Dynamic In Vitro Pilot Study

Background: Anterior cruciate ligament (ACL) injury increases the risk of meniscus and articular cartilage damage, but the causes are not well understood. Previous in vitro studies were static, required extensive knee dissection, and likely altered meniscal and cartilage contact due to the insertion of pressure sensing devices. Hypothesis: ACL deficiency will lead to increased translation of the lateral meniscus and increased deformation of the medial meniscus as well as alter cartilage contact location, strain, and area. Study Design: Descriptive laboratory study. Methods: With minimally invasive techniques, six 1.0-mm tantalum beads were implanted into the medial and lateral menisci of 6 fresh-frozen cadaveric knees. Dynamic stereo x-rays (DSXs) were obtained during dynamic knee flexion (from 15° to 60°, simulating a standing squat) with a 46-kg load in intact and ACL-deficient states. Knee kinematics, meniscal movement and deformation, and cartilage contact were compared by novel imaging coregistration. Results: During dynamic knee flexion from 15° to 60°, the tibia translated 2.6 mm (P = .05) more anteriorly, with 2.3° more internal rotation (P = .04) with ACL deficiency. The medial and lateral menisci, respectively, translated posteriorly an additional 0.7 mm (P = .05) and 1.0 mm (P = .03). Medial and lateral compartment cartilage contact location moved posteriorly (2.0 mm [P = .05] and 2.0 mm [P = .04], respectively). Conclusion: The lateral meniscus showed greater translation with ACL deficiency compared with the medial meniscus, which may explain the greater incidences of acute lateral meniscus tears and chronic medial meniscus tears. Furthermore, cartilage contact location moved further posteriorly than that of the meniscus in both compartments, possibly imparting more meniscal stresses that may lead to early degeneration. This new, minimally invasive, dynamic in vitro model allows the study of meniscus function and cartilage contact and can be applied to evaluate different pathologies and surgical techniques. Clinical Relevance: This novel model illustrates that ACL injury may lead to significant meniscus and cartilage abnormalities acutely, and these parameters are dynamically measurable while maintaining native anatomy.

Is There a Difference in Graft Motion for Bone-Tendon-Bone and Hamstring Autograft ACL Reconstruction at 6 Weeks and 1 Year?

Background: Bone–patellar tendon–bone (BTB) grafts are generally believed to heal more quickly than soft tissue grafts after anterior cruciate ligament (ACL) reconstruction, but little is known about the time course of healing or motion of the grafts within the bone tunnels. Hypothesis: Graft-tunnel motion will be greater in hamstring (HS) grafts compared with BTB grafts and will be less at 1 year than at 6 weeks. Study Design: Controlled laboratory study. Methods: Twelve patients underwent anatomic single-bundle ACL reconstruction using HS or BTB autografts (6 per group) with six 0.8-mm tantalum beads embedded in each graft. Dynamic stereo x-ray images were collected at 6 weeks and 1 year during treadmill walking and stair descent and at 1 year during treadmill running. Tibiofemoral kinematics and bead positions were evaluated. Graft-tunnel motion was based on bead range of motion during the loading response phase (first 10%) of the gait cycle. Results: During treadmill walking, there was no difference in femoral tunnel or tibial tunnel motion between BTB or HS grafts at 6 weeks (BTB vs HS: 2.00 ± 1.05 vs 1.25 ± 0.67 mm [femoral tunnel]; 1.20 ± 0.63 vs 1.27 ± 0.71 mm [tibial tunnel]), or 1 year (BTB vs HS: 1.62 ± 0.76 vs 1.08 ± 0.26 mm [femoral tunnel]; 1.58 ± 0.75 vs 1.68 ± 0.53 mm [tibial tunnel]). During stair descent, there was no difference in femoral or tibial tunnel motion between BTB and HS grafts at 6 weeks or 1 year. With running, there was no difference between graft types at 1 year. For all results, P values were > .05. Knee kinematics were consistent with the literature. Conclusion: During walking and stair descent, ACL reconstruction using suspensory fixation yielded no difference between graft types in femoral or tibial tunnel motion at 6 weeks or 1 year. All subjects were asymptomatic with knee kinematics similar to that of the literature. The significance of persistent, small (1 to 3 mm) movements at 1 year for healing or graft performance is unknown. Clinical Relevance: These study results may have significant implications for graft choice, rehabilitation strategies, and timing for return to sports.

ACL Reconstruction: Is There A Difference In Graft Motion For Bone-patellar Tendon-bone Vs Hamstring Autograft At 6 Weeks Post-operatively?

Objectives: Graft-tunnel healing following ACL reconstruction (ACLR) is a complex process influenced by multiple surgical variables, one of which is graft type. Clinical outcomes of bone-patellar tendon-bone (BTB) and hamstring (HS) autografts are similar, yet animal studies suggest that the healing processes may differ between the two autografts. Moreover, little is known about the relationship between graft-tunnel motion and the healing process in vivo in humans. This study was designed to compare BTB and HS graft motion within the femoral and tibial tunnels and the intra-articular graft post-operatively. We hypothesized that tunnel motion and mid-substance stretch would be greater for HS than BTB at 6 weeks following surgery. Methods: After IRB approval, 16 subjects (8 BTB, 8 HS) with an average age of 20 (range 16 to 37) underwent anatomic single-bundle ACLR by the same surgeon. Tunnel location, drilling and fixation were identical for all patients. Six 0.8 mm tantalum beads were embedded into ACL grafts prior to implantation using a custom injector. Pairs of beads were located within each bone tunnel and in the graft mid-substance (See image of graft constructs). Six weeks after surgery, CT scans were obtained and used to create 3D femur and tibia bone models. Cylindrical coordinate systems were fit to the bone tunnels to assess motion along tunnel axes. Dynamic stereo x-ray (DSX) images were collected at 100 frames/s while subjects performed treadmill walking and stair descent. Tibiofemoral kinematics were analyzed by combining the 3D models with DSX data. Graft-tunnel motion was defined as the maximum displacement of the implanted beads along the direction of the bone tunnel axis following footstrike. BTB and HS graft tunnel motions were compared using t-tests, with a significance level of p < 0.05. Results: Data are currently available for 6 BTB and 6 HS patients (N=12). Graft motion was seen in both groups within the femoral and tibial tunnels (range: 0.39 - 3.97 mm). Contrary to our hypothesis there was a trend towards greater femoral tunnel graft motion in the BTB relative to HS grafts during walking and stair descent (P=0.14 and 0.12, Table 1A-1B). There was more BTB graft motion in the femoral tunnel than in the tibial tunnel (significantly different for gait), and conversely more HS graft motion in the tibial tunnel than in the femoral tunnel (significantly different for stair descent). There was no detectable mid-substance stretch across all subjects. Conclusion: Six weeks following ACLR, less tunnel motion was expected for the BTB group compared to HS, due to the perceived advantages of bone-on-bone healing. However, more motion was observed for the BTB group within the femoral tunnel compared to HS, challenging the assumption that at 6 weeks after surgery there is greater graft-tunnel healing with BTB grafts. Based on previous studies, the native ACL elongates around 1-4% (0.3-1.2 mm) during loaded knee extension. At 6 weeks post surgery, it appears that the ACL grafts are moving in the tunnels rather than stretching in the mid-substance portion. This pattern may reverse over time, as graft-tunnel healing progresses (1-year followup testing is planned). Additionally, graft type appeared to affect the relative amount of motion between the tibial and femoral tunnels, though the cause and clinical significance of this finding is unclear. Results of this study could have important implications for graft selection, rehabilitation progression and return to sports.

Patient Reported Outcomes in Athletes following ORIF of Jones Fracture

Category: Lesser Toes, Midfoot/Forefoot, Sports Introduction/Purpose: Treatment of fractures to the 5th metatarsal metaphyseal-diaphyseal junction, known as Jones’ fractures, can present challenges in the elite athlete significantly prolonging return to play. Non-operative treatments in elite athletes result in a high incidence of nonunion and secondary fracture. Primary screw fixation remains the standard of care for athletes. However, delayed union and nonunion are still very common despite surgical fixation due to the fracture occurring in a watershed area with decreased healing potential. Bone marrow aspirate concentrate (BMAC) is an autologous source of hematopoeitic and mesenchymal stem cells that has been used in the treatment of poor healing fractures. We hypothesize that open reduction internal fixation (ORIF) augmented with BMAC will improve patient-reported outcome measures following Jones’ fractures in athletes. Methods: This study was a retrospective review of elite athletes that underwent intramedullary screw fixation augmented with BMAC for Jones’ fractures at an academic medical institution. All patients were assessed preoperatively and postoperatively to determine their pain outcomes based on their visual analog score (VAS). Student’s t test was used in statistical comparison of the preoperative and postoperative outcome scores. P < 0.05 was considered significant. Results: A total of 16 elite athletes were treated with ORIF with BMAC for a Jones fracture with a mean age of 22.2 years (range 19–26). There were 9 males and 7 females included in the study. Type of athlete ranged across various sport activities, with all patients functioning at a collegiate and/or professional level of elite athletics. The mean visual analog score for pain decreased from 6.2 preoperatively (range 3-8) to 2.75 postoperatively (range 1-6 p = 0.06). All patients have returned to elite competitive sport activity with reports of minimal to no pain. Conclusion: Intramedullary screw fixation of Jones’ fractures with BMAC results in optimal surgical outcomes in the elite athlete. A higher powered and long-term study with validated patient-reported outcomes is needed to confirm our observations.

Could Achilles Teondon Ruptures be Associated with Low Serum Free and Total Testosteron Levels

Purpose Serum free testosterone (FT) and total testosterone (TT) level were drawn in males with Achilles tendon rupture at time of injury and compared to healthy normal historical data as a means of evaluating if decreased sex hormone level is a risk factor for tendon injury. We hypothesized that males diagnosed with Achilles tendon ruptures will have lower FT and TT levels than age-matched normal levels in the literature.