Catherine Hui

Fifteen-Year Outcome of Endoscopic Anterior Cruciate Ligament Reconstruction With Patellar Tendon Autograft for “Isolated” Anterior Cruciate Ligament Tear

Background: Few studies report the long-term results of anterior cruciate ligament rupture and single-incision endoscopic reconstructive surgery. Outcomes are often clouded by concomitant meniscal, chondral, or ligament injuries. Purpose: To determine the 15-year outcomes of anterior cruciate ligament ruptures treated with endoscopic anterior cruciate ligament reconstruction using middle-third patellar tendon autograft. Study Design: Case series; Level of evidence, 4. Methods: Between January 1993 and April 1994, 333 consecutive patients underwent anterior cruciate ligament reconstruction. Patients with associated ligamentous injury requiring surgery, previous meniscectomy, or meniscal injury requiring more than one-third meniscectomy; chondral injury diagnosed at arthroscopy; and an abnormal contralateral knee were excluded. Ninety patients met the inclusion criteria. Outcomes included range of motion, Lachman and pivot-shift tests, instrumented ligament testing, single-legged hop test, Lysholm Knee Score, the International Knee Documentation Committee evaluation, and radiographic assessment. Results: Thirty percent of patients had further anterior cruciate ligament injury. Twenty-four percent of patients (n = 22) sustained contralateral anterior cruciate ligament ruptures, and 8% (n = 7) ruptured the graft (P = .009). Graft rupture was associated with a graft inclination angle <17° (P = .02). Contralateral anterior cruciate ligament rupture was associated with age <18 years at time of primary injury (P = .001). All patients had normal or nearly normal (International Knee Documentation Committee evaluation) Lachman and instrumented testing, and 91% had a negative pivot-shift result. Seventy percent of patients had kneeling pain. Median subjective International Knee Documentation Committee evaluation was 91 of 100. Fifty-one percent of patients had radiographic evidence of osteoarthritis (41% grade B; 10% grade C). Conclusion: Good results are maintained at 15 years after surgery with respect to ligamentous stability, subjective outcomes, and range of motion. Kneeling pain remains a significant problem. Concern remains regarding the incidence of further anterior cruciate ligament injury and the increasing number of patients with radiographic and clinical signs of osteoarthritis despite surgical stabilization.

Long-term survival of high tibial osteotomy for medial compartment osteoarthritis of the knee.

Background: The management of degenerative arthritis of the knee in the younger, active patient presents a challenge to the orthopaedic surgeon. Surgical treatment options include high tibial osteotomy (HTO), unicompartmental knee arthroplasty, and total knee arthroplasty. Purpose: To examine the long-term survival of closing wedge HTO in a large series of patients up to 19 years after surgery. Study Design: Case series; Level of evidence, 4. Methods: Four hundred fifty-five consecutive patients underwent lateral closing wedge HTO for medial compartment osteoarthritis between 1990 and 2001. Between 2008 and 2009, patients were contacted via telephone, and assessment included incidence of further surgery, current body mass index (BMI), Oxford Knee Score, and British Orthopaedic Association Patient Satisfaction Scale. Failure was defined as the need for revision HTO or conversion to unicompartmental knee arthroplasty or total knee arthroplasty. Survival analysis was completed using the Kaplan-Meier method. Results: High tibial osteotomy survival was determined in 413 patients (91%). Of the 397 remaining living patients at the time of final review, 394 (99%) were contacted for follow-up via telephone interview. The probability of survival for HTO at 5, 10, and 15 years was 95%, 79%, and 56%, respectively. Multivariate regression analysis showed that age under 50 years (P = .001), BMI less than 25 (P = .006), and ACL deficiency (P = .03) were associated with better odds of survival. Mean Oxford Knee Score was 40 of 48 (range, 17-48). Overall, 85% of patients were enthusiastic or satisfied, and 84% would undergo HTO again at a mean 12 years of follow-up. Conclusion: High tibial osteotomy can be effective for periods longer than 15 years; however, results do deteriorate over time. Age less than 50 years, normal BMI, and ACL deficiency were independent factors associated with improved long-term survival of HTO.

Outcome of Anatomic Transphyseal Anterior Cruciate Ligament Reconstruction in Tanner Stage 1 and 2 Patients With Open Physes

Background: Anterior cruciate ligament (ACL) injuries are being seen with increasing frequency in children. Treatment of the ACL-deficient knee in skeletally immature patients is controversial. Purpose: To determine the outcome of all-arthroscopic transphyseal anatomic single-bundle ACL reconstruction in Tanner stage 1 and 2 patients at a minimum of 2 years after surgery. Study Design: Case series; Level of evidence, 4. Methods: Between 2007 and 2008, 16 prepubescent patients underwent ACL reconstruction using soft tissue grafts. All patients were Tanner stage 1 and 2. Outcomes were assessed at a minimum of 2 years after surgery and included limb alignment, limb length, instrumented testing with the KT-1000 arthrometer, and International Knee Documentation Committee (IKDC) score. Results: Mean age at the time of surgery was 12 years (range, 8-14 years). Graft choices included the following: living donor–related hamstring tendon allograft (n = 14), hamstring tendon autograft (n = 1), and fresh-frozen allograft (n = 1). Mean IKDC subjective score was 96 (range, 84-100). All patients had a stable knee postoperatively. Eleven patients had a negative Lachman test result, and 14 had a negative pivot-shift test result. The remainder had grade 1 Lachman and pivot-shift test findings, respectively. At 2 years after surgery, all patients had returned to strenuous activities, and normal or nearly normal overall IKDC score was documented in 94% of patients. There were no cases of limb malalignment or growth arrest. Conclusion: We present a case series of transphyseal anatomic single-bundle ACL reconstruction in Tanner stage 1 and 2 patients at a minimum of 2 years after surgery. Excellent clinical outcomes were obtained with high levels of return to desired activities. Importantly, no growth disturbances were seen in this series of patients.

Five-Year Comparison of Oxidized Zirconium and Cobalt-Chromium Femoral Components in Total Knee Arthroplasty: A Randomized Controlled Trial

BACKGROUND In vitro analysis has shown that oxidized zirconium on ultra-high molecular weight polyethylene has better wear properties than cobalt-chromium on ultra-high molecular weight polyethylene. The purpose of this study was to determine if oxidized zirconium femoral components performed better than cobalt-chromium in vivo and if the use of oxidized zirconium components had clinical adverse effects. METHODS Forty consecutive patients (eighty knees) underwent simultaneous bilateral cruciate-retaining total knee arthroplasty for primary osteoarthritis from January 2002 to December 2003. For each patient, the knees were randomized to receive the oxidized zirconium femoral component, with the contralateral knee receiving the cobalt-chromium component. Outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index, Knee Injury and Osteoarthritis Outcome Score, Knee Society score, and British Orthopaedic Association patient satisfaction scale. Radiographic outcomes include the Knee Society total knee arthroplasty roentgenographic evaluation and scoring system and measurement of radiographic wear. Patients and assessors were blinded to the treatment groups and results. RESULTS There were no significant differences in clinical, subjective, and radiographic outcomes between the two implants at five days, six weeks, and one, two, or five years postoperatively. At five years following surgery, 38% of the patients preferred the cobalt-chromium knee compared with 18% who preferred the oxidized zirconium knee (p = 0.02) and 44% had no preference. CONCLUSIONS Five-year outcomes after total knee arthroplasty with oxidized zirconium and cobalt-chromium femoral components showed no significant differences in clinical, subjective, and radiographic outcomes. Patients had no preference or preferred the cobalt-chromium prosthesis to the oxidized zirconium prosthesis at the time of the five-year follow-up. There were no adverse effects associated with the use of oxidized zirconium femoral implants.

Three-Dimensional Intercondylar Notch Volumes in a Skeletally Immature Pediatric Population: A Magnetic Resonance Imaging–Based Anatomic Comparison of Knees With Torn and Intact Anterior Cruciate Ligaments

PURPOSE To determine whether 3-dimensional notch volume, measured with magnetic resonance imaging (MRI), differs significantly between knees with torn and intact anterior cruciate ligaments (ACLs) after sports injury in a skeletally immature pediatric population. METHODS MRI studies of 50 pediatric patients (age range, 10 to 17 years) with ACL tears were compared with 50 age- and sex-matched intact-ACL control patients. All patients had open physes and underwent MRI after a sports injury. Notch volume was calculated through manual segmentation of notch boundaries seen on axial 1.5-T proton density-weighted images. Two-dimensional (2D) measurements (notch width and notch width index) were made on coronal proton density-weighted MRI studies. Notch volume was compared between groups by use of the Mann-Whitney U test. Pearson correlation coefficients were also calculated between indices. RESULTS Notch volume was significantly lower in knees with ACL tears than in control knees (5.5 ± 1.1 cm(3)v 6.4 ± 1.5 cm(3), P = .002), whereas 2D notch width and notch width index did not differ significantly between these groups. Girls had significantly smaller notch volumes than boys (5.4 ± 1.2 cm(3)v 6.5 ± 1.3 cm(3), P < .001). Notch volume was not correlated with age but was moderately correlated with 2D notch width (r = 0.485, P < .001). CONCLUSIONS In adolescent patients with sports injuries, the 3-dimensional notch volume was significantly smaller in knees with ACL tears than in intact-ACL control knees. Notch volume was also significantly smaller in girls than in boys and did not vary significantly with age. LEVEL OF EVIDENCE Level III, case-control study.

Five-year changes in gait biomechanics after concomitant high tibial osteotomy and ACL reconstruction in patients with medial knee osteoarthritis.

Background: Concomitant high tibial osteotomy (HTO) and anterior cruciate ligament (ACL) reconstruction is a combined surgical procedure intended to improve kinematics and kinetics in the unstable ACL-deficient knee with varus malalignment and medial compartment knee osteoarthritis (OA). Purpose: To investigate 5-year changes in gait biomechanics as well as radiographic and patient-reported outcomes bilaterally after unilateral, concomitant medial opening wedge HTO and ACL reconstruction. Study Design: Controlled laboratory study. Methods: A total of 33 patients (mean ± SD age, 40 ± 9 years) with varus malalignment (mean mechanical axis angle, −5.9° ± 2.9°), medial compartment knee OA, and ACL deficiency completed 3-dimensional gait analysis preoperatively and 2 and 5 years postoperatively. Primary outcomes were the peak external knee adduction (first peak) and flexion moments. Secondary outcomes were the peak external knee extension and transverse plane moments, peak knee angles in all 3 planes, radiographic static knee alignment measures (mechanical axis angle and posterior tibial slope), and the Knee injury and Osteoarthritis Outcome Score (KOOS). Results: There was a substantial decrease in the knee adduction moment in the surgical limb (%BW × H, −1.49; 95% CI, −1.75 to −1.22) and a slight increase in the nonsurgical limb (%BW × H, 0.16; 95% CI, 0.03 to 0.30) from preoperatively to 5 years postoperatively. There was also a decrease in the knee flexion moment for both the surgical (%BW × H, −0.67; 95% CI, −1.19 to −0.15) and nonsurgical limbs (%BW × H, –1.06; 95% CI, –1.49 to −0.64). Secondary outcomes suggested that substantial improvements were maintained at 5 years, although smaller declines were observed in several measures and in both limbs from 2 to 5 years. Conclusion: Changes in the peak external moments about the knee in all 3 planes during walking were observed 5 years after concomitant medial opening wedge HTO and ACL reconstruction. These findings are consistent with an intended, sustained shift in the mediolateral distribution of knee loads. Clinical Relevance: These findings suggest that concomitant HTO and ACL reconstruction results in substantial changes in gait biomechanics. Future clinical research comparing treatment strategies is both warranted and required for this relatively uncommon but seemingly biomechanically efficacious procedure.

MRI Anatomy of the Tibial ACL Attachment and Proximal Epiphysis in a Large Population of Skeletally Immature Knees Reference Parameters for Planning Anatomic Physeal-Sparing ACL Reconstruction

Background: To aid in performing anatomic physeal-sparing anterior cruciate ligament (ACL) reconstruction, it is important for surgeons to have reference data for the native ACL attachment positions and epiphyseal anatomy in skeletally immature knees. Purpose: To characterize anatomic parameters of the ACL tibial insertion and proximal tibial epiphysis at magnetic resonance imaging (MRI) in a large population of skeletally immature knees. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The ACL tibial attachment site and proximal epiphysis were examined in 570 skeletally immature knees with an intact ACL (age, 6-15 years) using 1.5-T proton density–weighted sagittal MRI; also measured were the tibial anteroposterior diameter; anterior, central, and posterior ACL attachment positions; vertical height of the epiphysis; and maximum oblique epiphyseal depth extending from the ACL tibial attachment center to the tibial tuberosity. Results: In adolescents (11-15 years of age), the center of the ACL’s tibial attachment was 51.5% ± 5.7% of the anteroposterior diameter of the tibia, with no significant differences between sexes or age groups (P > .05 in all cases). Mean vertical epiphyseal height was 15.9 ± 1.7 mm in the adolescent group, with significant differences between 11-year-olds (15.2 ± 1.5 mm) and 15-year-olds (16.6 ± 1.6 mm), P < .001, and between males (16.6 ± 1.5 mm) and females (14.8 ± 1.4), P < .001. Mean maximum oblique depth was 30.0 ± 5.3 mm, with a significant difference between 11-year-olds (26.7 ± 4.9 mm) and 15-year-olds (32.7 ± 5.1 mm), P < .001, and between males (29.7 ± 6.4 mm) and females (27.8 ± 5.2 mm), P < .001. The maximum oblique depth occurred at a mean angle of ~50°, and this angle did not change with age or sex. There was a significant moderate correlation (r = 0.39, P < .001) between epiphyseal vertical height and maximum oblique depth. Conclusion: The center of the ACL tibial attachment was consistently near 51% of the anteroposterior diameter, regardless of age or sex. The vertical depth of the tibial epiphysis was ~16 mm in adolescents. Maximum oblique depth from ACL attachment was ~30 mm, occurring at a mean angle ~50° regardless of age or sex. The normative values for tibial ACL attachment and epiphyseal anatomy presented here may be helpful in selecting candidates for surgery and in planning surgical approaches for pediatric ACL reconstruction.

Purification and some properties of Saccharomyces cerevisiae meiosis-specific protein kinase Ime2

Ime2 is the founding member of a family of protein kinases that are required for effective progression through meiotic development. Ime2 is essential for the induction of meiosis-specific genes and for the activation of meiotic DNA replication in the budding yeast Saccharomyces cerevisiae. Aside from the fact that Ime2 is a protein kinase and shares several amino acid motifs with cyclin dependent kinases, virtually nothing is known about its enzymatic properties or substrates. Biochemical characterization of Ime2 has been hindered by its low abundance and short half-life. We have created baculovirus expression vectors to produce recombinant Ime2 in insect cells. In this report, we describe the overproduction of Ime2 and its purification using affinity chromatography. Using this procedure, we have been able to purify up to 2mg Ime2 from 1L of infected insect cells. The Ime2 isolated by this method displays properties similar to those of the native enzyme that has been immunoprecipitated from yeast. The high level expression of Ime2 in this system and its ease of purification will be beneficial for more extensive biochemical analysis of Ime2 and related meiosis-specific kinases.

Reliability of estimates of ACL attachment locations in 3-dimensional knee reconstruction based on routine clinical MRI in pediatric patients.

Background: Current techniques of anterior cruciate ligament (ACL) reconstruction focus on the placement of femoral and tibial tunnels at anatomic ACL attachments, which can be difficult to identify intraoperatively. Purpose: To determine whether the 3-dimensional (3D) center of ACL attachments can be reliably detected from routine magnetic resonance imaging (MRI) in patients with intact ACLs and whether the reliability of this technique changes if the ACL is torn. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A computer technique was developed in which users identify points along ACL attachments on routine clinical MRI of preoperative knees. These attachments are then displayed on a 3D MRI reconstruction, which can be used as a visual guide for the surgeon during arthroscopic surgery. Thirty-seven pediatric patients (age range, 10-17 years) with ACL tears and 37 controls with intact ACLs were examined. Two blinded observers identified cruciate ligament attachments on routine clinical 1.5-T MRI of knees. From the resulting 3D model, the location of the center of each ligament attachment site and its area were calculated and reliability assessed. Results: Mean interobserver variation of the centers of ACL attachments for the intact versus torn ACL was 1.7 ± 0.9 mm versus 1.8 ± 1.1 mm (femoral) and 1.4 ± 0.9 mm versus 1.7 ± 1.0 mm (tibial), respectively (P > .05). The 95% confidence interval for the center location was at most 4 mm. The identified ACL attachment areas were more variable, with interobserver reliability ranging from fair to excellent by the intraclass correlation coefficient. Overlap of ligament areas between observers for the intact versus torn ACL was 70% ± 15% versus 73% ± 12% (femoral) and 79% ± 9% versus 78% ± 10% (tibial), respectively (P > .05). In all cases, intraobserver reliability was superior to interobserver reliability. Conclusion: The 3D locations of ACL tibial and femoral attachment centers were identified from routine clinical MRI with variability averaging less than 2 mm between 2 observers. The margin of error was at most 4 mm, representing the thickness of a single axial MRI slice, whether the ACL was intact or torn. Remnant tissue at attachments allows a reliable assessment even of torn ligaments. Identification of the ligament attachment areas was more user dependent than was identification of the attachment centers.

A Validation Study of a Novel 3-Dimensional MRI Modeling Technique to Identify the Anatomic Insertions of the Anterior Cruciate Ligament

Background: Anatomic single bundle anterior cruciate ligament (ACL) reconstruction is the current gold standard in ACL reconstructive surgery. However, placement of femoral and tibial tunnels at the anatomic center of the ACL insertion sites can be difficult intraoperatively. We developed a “virtual arthroscopy” program that allows users to identify ACL insertions on preoperative knee magnetic resonance images (MRIs) and generates a 3-dimensional (3D) bone model that matches the arthroscopic view to help guide intraoperative tunnel placement. Purpose: To test the validity of the ACL insertion sites identified using our 3D modeling program and to determine the accuracy of arthroscopic ACL reconstruction guided by our “virtual arthroscopic” model. Study Design: Descriptive laboratory study. Methods: Sixteen cadaveric knees were prescanned using routine MRI sequences. A trained, blinded observer then identified the center of the ACL insertions using our program. Eight knees were dissected, and the centers of the ACL footprints were marked with a screw. In the remaining 8 knees, arthroscopic ACL tunnels were drilled into the center of the ACL footprints based on landmarks identified using our virtual arthroscopic model. Postprocedural MRI was performed on all 16 knees. The 3D distance between pre- and postoperative 3D centers of the ACL were calculated by 2 trained, blinded observers and a musculoskeletal radiologist. Results: With 2 outliers removed, the postoperative femoral and tibial tunnel placements in the open specimens differed by 2.5 ± 0.9 mm and 2.9 ± 0.7 mm from preoperative centers identified on MRI. Postoperative femoral and tibial tunnel centers in the arthroscopic specimens differed by 3.2 ± 0.9 mm and 2.9 ± 0.7 mm, respectively. Conclusion: Our results show that MRI-based 3D localization of the ACL and our virtual arthroscopic modeling program is feasible and does not show a statistically significant difference to an open arthrotomy approach. However, additional refinements will be required to improve the accuracy and consistency of our model to make this an effective tool for surgeons performing anatomic single-bundle ACL reconstructions. Clinical Relevance: Arthroscopic anatomic single-bundle ACL reconstruction is the current gold standard for ACL reconstruction; however, the center of the ACL footprint can be difficult to identify arthroscopically. Our novel modeling can improve the identification of this important landmark intraoperatively and decrease the risk of graft malposition and subsequent graft failure.