Nicholas I. Kennedy

Kinematic Analysis of the Posterior Cruciate Ligament, Part 2 A Comparison of Anatomic Single- Versus Double-Bundle Reconstruction

Background: A more thorough understanding of the posterior cruciate ligament (PCL) has led to an increase in awareness and treatment of complex PCL injuries. Controversy exists about whether PCL reconstruction (PCLR) using an anatomic single-bundle (aSB) or anatomic double-bundle (aDB) technique is the most effective. Hypothesis: An aDB PCLR provides significantly better anterior-posterior and rotatory knee stability compared with an aSB PCLR and more closely recreates normal knee kinematics. Study Design: Controlled laboratory study. Methods: A total of 18 match-paired, cadaveric knees (mean age, 54.8 years; range, 51-59 years; 5 male and 4 female pairs) were used to evaluate the kinematics of an intact PCL, an aSB and aDB PCLR, and a complete sectioned PCL. A 6 degrees of freedom robotic system was used to assess knee stability with a 134-N applied posterior tibial load, 5-N·m external and internal rotation torques, 10-N·m valgus and varus rotation torques, and a coupled 100-N posterior tibial load and 5-N·m external rotation torque at 0°, 15°, 30°, 45°, 60°, 75°, 90°, 105°, and 120°. Results: The aDB PCLR had significantly less posterior translation than the aSB PCLR at all flexion angles of 15° and greater. The largest difference in posterior translation was seen at 105° of flexion, where the aSB PCLR had 5.3 mm (P = .017) more posterior translation than the aDB PCLR. The aDB PCLR also had significantly less internal rotation than the aSB PCLR at all tested angles of 90° and greater. Neither reconstruction was able to fully restore native knee kinematics. Conclusion: An aDB PCLR more closely approximated native knee kinematics when compared with an aSB PCLR. Specifically, the aDB PCLR demonstrated significantly more restraint to posterior translation at flexion angles between 15° and 120° and less internal rotational laxity at high flexion angles 90° to 120°. Clinical Relevance: Comparison of the 2 reconstruction techniques illustrates the time-zero kinematic advantage imparted by the addition of the posteromedial bundle reconstruction. The benefit is most pertinent for resistance to posterior translation across a full range of flexion and rotational stability beyond 90° of knee flexion.

Kinematic Analysis of the Posterior Cruciate Ligament, Part 1 The Individual and Collective Function of the Anterolateral and Posteromedial Bundles

Background: The posterior cruciate ligament (PCL) is composed of 2 functional bundles and has an essential role in knee function and stability. There is, however, a limited understanding of the role of each individual bundle through the full range of knee flexion. Hypothesis: Both bundles provide restraint to posterior tibial translation across a full range of knee flexion. At higher angles of knee flexion (>90°), the intact PCL also imparts significant rotational stability. Study Design: Controlled laboratory study. Methods: Twenty matched-paired, human cadaveric knees (mean age, 55.2 years; range, 51-59 years; 6 male and 4 female pairs) were used to evaluate the kinematics of an intact, anterolateral bundle (ALB) sectioned, posteromedial bundle (PMB) sectioned, and complete PCL sectioned knee. A 6 degree of freedom robotic system was used to assess knee stability with an applied 134-N posterior tibial load, 5-N·m external and internal rotation torques, 10-N·m valgus and varus torques, and a coupled 100-N posterior tibial load and 5-N external rotation torque at 0°, 15°, 30°, 45°, 60°, 75°, 90°, 105°, and 120°. Results: All sectioned states had significant increases compared with intact in posterior translation, internal rotation, and external rotation at all tested flexion angles, with the exception of the ALB sectioned state at 75° of flexion for external rotation. The significant increases (mean ± standard deviation) in posterior translation during a 134-N posterior tibial load at 90° of flexion were 0.9 ± 0.6 mm, 2.6 ± 1.8 mm, and 11.7 ± 4.0 mm for the PMB, ALB, and complete PCL sectioned states, respectively, compared with the intact state. The largest significant increases in internal rotation were in the PMB and complete PCL sectioned states at 105° of flexion, 1.3° ± 1.0° and 2.8° ± 2.1°, respectively. Conclusion: Both the ALB and the PMB assume a significant role in resisting posterior tibial translation, at all flexion angles, suggesting a codominant relationship. The PCL provided a significant constraint to internal rotation beyond 90° of flexion. Clinical Relevance: This information broadens the understanding of native knee kinematics and provides a template for the evaluation of single- and double-bundle PCL reconstructions.

Posterior Cruciate Ligament Graft Fixation Angles, Part 1: Biomechanical Evaluation for Anatomic Single-Bundle Reconstruction

Background: Currently, no consensus exists for the optimal graft fixation angle for anatomic single-bundle (SB) posterior cruciate ligament reconstructions (PCLRs). Additionally, direct graft forces have not been measured. Alternative graft fixation angles and the resultant graft forces should be investigated to optimize the stability of SB PCLRs without overconstraining the knee. Hypothesis: Graft fixation angles of 75°, 90°, and 105° for SB PCLR were hypothesized to improve knee stability compared with the sectioned posterior cruciate ligament state with no evidence of knee overconstraint. Study Design: Controlled laboratory study. Methods: Nine fresh-frozen human cadaveric knees were biomechanically evaluated for the intact, sectioned, and SB PCLR states with the anterolateral bundle graft fixed at 75°, 90°, and 105°. A 6 degrees of freedom robotic system assessed knee laxity with a 134-N posterior load applied at 0° to 120° and 5-N·m external, 5-N·m internal, and 10-N·m valgus rotation torques applied at 60° to 120°. By securing the graft to an external load cell, graft forces were measured throughout kinematic testing. Results: No significant kinematic differences were found among the 3 fixation angles. Each fixation angle resulted in significantly less posterior translation than in the sectioned state at all flexion angles (P < .05), with 4.1 mm of average residual laxity during an applied posterior loading. For all graft fixation angles, internal rotation was significantly increased between 60° and 120° of flexion, and external rotation was significantly increased at 90°, 105°, and 120° of flexion compared with the intact state. Graft forces were not significantly different among the 3 fixation angles and remained below reported loads observed during activities of daily living. Conclusion: All tested SB PCLR graft fixation angles restored knee laxity to similar levels; however, persistent laxity resulted in significant increases in knee laxity compared with the intact state during posterior tibial loading at all flexion angles, internal rotation at flexion angles ≥60°, and external rotation at ≥75° of flexion. Clinical Relevance: The results of this study suggest that SB PCL graft fixation angles of 75°, 90°, and 105° were comparable in restoring knee kinematics and exposed the graft to similar time-zero loads. However, SB PCLRs did not fully reduce knee laxity to the intact state.

Superficial Medial Collateral Ligament Anatomic Augmented Repair Versus Anatomic Reconstruction: An In Vitro Biomechanical Analysis

Background: When surgical intervention is required for a grade 3 superficial medial collateral ligament (sMCL) tear, there is no consensus on the optimal surgical treatment. Anatomic augmented repairs and anatomic reconstructions for treatment of grade 3 sMCL tears have not been biomechanically validated or compared. Hypothesis: Anatomic sMCL augmented repairs and anatomic sMCL reconstruction techniques will reproduce equivalent knee kinematics when compared with the intact state, while creating significant improvements in translational and rotational laxity compared with the sMCL sectioned state. Study Design: Controlled laboratory study. Methods: Eighteen match-paired, fresh-frozen cadaveric knees (average age, 52.6 years; range, 40-59 years) were each used to test laxity of an intact sMCL, a deficient sMCL, and either an anatomic augmented repair or an anatomic reconstruction. Knees were biomechanically tested in a 6 degrees of freedom robotic system, which included valgus rotation, internal and external rotation, simulated pivot shift, and coupled anterior drawer with external rotation. Results: Anatomic augmented repairs and anatomic reconstructions had significantly less medial joint gapping than the sectioned state at all tested flexion angles and showed significant reductions in valgus rotation compared with the sectioned state at all flexion angles. No significant differences between the anatomic augmented repair and anatomic reconstruction were found for any test performed. Despite the similar behavior between the 2 reconstruction groups, neither technique was able to reproduce the intact state. Conclusion: Anatomic sMCL augmented repairs and anatomic sMCL reconstructions were not significantly different when tested at time zero. Both the anatomic augmented repair and the anatomic reconstruction were able to improve knee stability and provide less than 2 mm of medial joint gapping at 0° and 20° of flexion. Clinical Significance: These results suggest that both an anatomic sMCL augmented repair and an anatomic sMCL reconstruction improve knee kinematics compared with a deficient sMCL and provide equivalent joint stability.

Iatrogenic Meniscus Posterior Root Injury Following Reconstruction of the Posterior Cruciate Ligament A Report of Three Cases

The diagnosis of meniscus root tears has become more common as the clinical and radiographic awareness of these injuries has increased1,2. Detachment of the meniscal roots from their tibial posterior attachments can cause meniscal extrusion and joint space narrowing, and also has been associated with progressive knee arthritis3,4. Meniscal root detachments have been demonstrated to result in a loss of meniscal hoop stress and to subject the articular cartilage to abnormal contact forces, equivalent to those experienced after a total meniscectomy5,6. In addition, knowledge about and understanding of the attachment sites of the menisci have been enhanced by quantitative and qualitative anatomic studies7. The close proximity of the medial and lateral meniscus root attachments to the tibial footprint of the posterior cruciate ligament (PCL) is pertinent because it renders these structures vulnerable when drilling a transtibial tunnel for a PCL reconstruction8. As interest in and enthusiasm for PCL reconstructions increase, it is important to be cognizant of this close relationship since iatrogenic detachment of meniscal roots represents a potential risk of this procedure. We present a series of cases in which posterior horn meniscal roots were detached iatrogenically because of malpositioning of the transtibial PCL reconstruction tunnels. The institutional review board at the Vail Valley Medical Center in Colorado provided approval for this case series. The patients were informed that data concerning their cases would be submitted for publication, and they provided consent. The three patients described in this case report were originally operated on by a surgeon at an outside institution, and they all were noted to have failed PCL reconstructions at the initial presentation to our facility. Case 1. A twenty-one-year-old man presented with recurrent right knee instability. The original injury …

Surgical Management and Treatment of the Anterior Cruciate Ligament/Posterolateral Corner Injured Knee

Posterolateral knee injuries occur more commonly than in the past. These injuries most commonly occur concurrent with cruciate ligament tears. The main stabilizers of the posterolateral knee are the fibular collateral ligament, the popliteus tendon, and the popliteofibular ligament. These static stabilizers function to prevent increased varus, external rotation, and coupled posterolateral rotation of the knee. The most important clinical tests to diagnose posterolateral knee injuries are the varus stress test, posterolateral drawer, and dial tests. Varus stress radiographs are key objective means to diagnose these injuries. Anatomic- based reconstructions have been validated to restore stability and improve outcomes.

The Supine Internal Rotation Test: A Pilot Study Evaluating Tibial Internal Rotation in Grade III Posterior Cruciate Ligament Tears.

Background: Biomechanical studies have reported that the posterior cruciate ligament (PCL) functions as a restraint against excessive tibial internal rotation at higher degrees of knee flexion. Purpose: To investigate the use of a supine internal rotation (IR) test for the diagnosis of grade III PCL injuries. The hypothesis was that internal rotation would be greater in patients with grade III PCL injuries compared with other knee injuries and that the supine IR test would demonstrate excellent diagnostic accuracy. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: A consecutive series of 309 patients underwent arthroscopic and/or open knee ligament reconstruction surgery. Seven patients were excluded based on the inability to perform a side-to-side comparison of internal rotation. Tibial internal rotation was assessed bilaterally on 302 patients during examination under anesthesia by a single orthopaedic surgeon measuring tibial tubercle excursion (mm) while applying internal rotation torque. Internal rotation was graded from 0 to 4 at 60°, 75°, 90°, 105°, and 120° of knee flexion. Data were collected and stored prospectively. The optimal threshold for the supine IR test was chosen based on maximization of the Youden index. Diagnostic accuracy parameters were calculated. Multiple logistic regression models were constructed to assess the influence of other knee pathologies on diagnostic accuracy. Results: Examination of the 22 PCL-deficient knees demonstrated an increase in tibial internal rotation at 60°, 75°, 90°, 105°, and 120° of knee flexion. The supine IR test had a sensitivity of 95.5%, a specificity of 97.1%, a positive predictive value of 72.4%, and a negative predictive value of 99.6% for the diagnosis of grade III PCL injuries. Posterolateral corner injury had a significant interaction with the supine IR test, increasing its sensitivity and decreasing its specificity. Conclusion: PCL-deficient knees demonstrated an increase in the side-to-side difference in tibial internal rotation compared with other knee pathologies. The supine IR test offers high sensitivity and specificity for grade III PCL injuries and may represent a useful adjunct for diagnosing PCL injuries.

Outcomes and Complication Rates After Primary Anterior Cruciate Ligament Reconstruction Are Similar in Younger and Older Patients

Background: Until recently, anterior cruciate ligament (ACL) tears in older patients were treated conservatively; however, these patients often experienced significant pain and instability. Purpose/Hypothesis: The purpose of this study was to compare the patient-reported outcomes, patient satisfaction, and failure rates of primary ACL reconstruction between a younger (age 20-30 years) and older (age 50-75 years) patient cohort. It was hypothesized that patients in the older cohort could achieve comparable clinical outcomes and retear rates following ACL reconstruction with a bone-tendon-bone autograft or allograft compared with the younger patients. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective analysis of prospectively collected data was performed. All patients undergoing a primary ACL reconstruction between 2010 and 2014 by a single surgeon were collated. Patients were divided into 2 groups based on age at the time of surgery: a younger cohort (20-30 years) and an older cohort (50-75 years). Patients were excluded if they were outside the desired age intervals; had revision ACL reconstructions; had a previous intra-articular infection in the ipsilateral knee; underwent prior alignment correction procedure, cartilage repair, or transplant procedure; had a concurrent posterior cruciate ligament tear; received meniscal allograft transplant; or had an intra-articular fracture. Subjective outcome scores (Tegner activity scale, Lysholm, International Knee Documentation Committee [IKDC], Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], Short Form–12 [SF-12] mental health component summary [MCS], and SF-12 physical component summary [PCS]), retear rate, and rate of secondary arthrofibrosis surgery were documented at a minimum 2-year follow-up and were compared between groups. Results: A total of 85 patients met the inclusion criteria for this study: 52 patients (33 males, 19 females) in the younger cohort and 33 patients (14 males, 19 females) in the older cohort. No significant differences were found in any demographic factor except for age. Significant improvement in outcome scores from pre- to postoperative assessments was found in both groups. The younger cohort had significantly lower postoperative WOMAC scores (P = .025). However, no significant differences were found between the younger and older cohorts in postoperative SF-12 PCS (P = .487), SF-12 MCS (P = .900), Lysholm score (P = .660), IKDC score (P = .256), Tegner activity score (P = .420), or patient satisfaction (P = .060). Within the older cohort, increasing age did not correlate with inferior postoperative outcome scores. Furthermore, no retears occurred in either group, and the rates of arthrofibrosis surgery were comparable (12% older cohort vs 13% younger cohort). Conclusion: Improved function and satisfaction, comparable to the younger age group, were achieved in patients older than 50 years undergoing ACL reconstruction. Furthermore, low failure rates can be achieved in both younger and older patients undergoing ACL reconstruction.

Open Repair of Quadriceps Tendon With Suture Anchors and Semitendinosus Tendon Allograft Augmentation

Quadriceps tendinopathy in an increasingly recognized diagnosis can lead to quadriceps tendon rupture, especially in the older population. It can be caused by repeated micro trauma or also predisposed by systemic diseases such as diabetes mellitus and connective tissue disorders that can in turn lead to extensor mechanism deficits. Although a trial of conservative treatment is advocated, operative treatment should be performed in cases of persistent pain, extension deficit, or complete rupture of the tendon. The purpose of this Technical Note is to describe in detail a procedure for open repair of a quadriceps tendon, with significant degeneration due to quadriceps tendinopathy, using suture anchors and semitendinosus tendon allograft augmentation.

Inside-Out Repair of Meniscal Ramp Lesions

Meniscal ramp lesions have been reported to be present in 9% to 17% of patients undergoing anterior cruciate ligament reconstruction. Detection at the time of arthroscopy can be accomplished based upon clinical suspicion and careful evaluation without the use of an accessory posteromedial portal. Options for surgical treatment include arthroscopic repair using an all-inside or inside-out technique. The purpose of this Technical Note is to detail our arthroscopic inside-out repair technique for meniscal ramp lesions.