Preoperative Performance of Patient-Reported Outcomes Measurement Information System in Patients with Meniscal Root Tears

The purpose of this study was to establish preoperative validity of the Patient-Reported Outcomes Measurement Information System physical function computer adaptive test (PROMIS PF-CT) with legacy patient-reported outcome measures (PROMs) for meniscal root tears (MRTs). Our study included 51 patients (52 knees) with MRT. Patients completed PROMIS PF-CT, Short Form 36 (SF-36 physical function, pain, general health, vitality, social function, emotional well-being, role limitations due to physical health, and role limitations due to emotional problems), Knee Injury and Osteoarthritis Outcome Score (KOOS pain, symptoms, activities of daily living [ADLs], sports, and quality of life [QOL]), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC pain, stiffness, and function), EuroQol-5 dimensions (EQ-5D), and Knee Activity Scale questionnaires at their preoperative visit. Correlations between the PROMs listed above were evaluated along with floor and ceiling effects. Correlations were defined as weak (0.2-0.39), moderate (0.4-0.59), strong (0.6-0.79), and very strong (0.8-1.0). Preoperative data showed that PROMIS PF-CT has a strong correlation with SF-36 PF, KOOS-ADL, WOMAC-function, and EQ-5D; and moderate correlation with KOOS-sport, KOOS-pain, KOOS-symptoms, KOOS-QOL, WOMAC-pain, and WOMAC-stiffness. The Knee Activity Scale did not show any significant correlation with PROMIS PF-CT (r = 0.12, p = 0.2080). Of all the PROMs administered, PROMIS PF-CT demonstrated no floor or ceiling effects compared with 11.54% ceiling effect in KOOS-sports, and 5.77% floor effect in KOOS-ADL. On average, patients answered fewer PROMIS PF-CT questions (4.15 ± 0.72). PROMIS PF-CT is a valuable tool to assess preoperative patient-reported physical function in patients that may undergo MRT repair. It correlates strongly with other well-established PROMs. It also demonstrated no floor or ceiling effects and demonstrated a low test burden in our sample of 52 knees. This is a level III, prognostic retrospective comparative study.

Preoperative Opioid Usage, Male Sex, and Preexisting Knee Osteoarthritis Impacts Opioid Refills After Isolated Arthroscopic Meniscectomy: A Population-Based Study

PURPOSE

To identify risk factors for opioid consumption after arthroscopic meniscectomy using a large national database.

METHODS

Patients undergoing primary arthroscopic meniscectomy from 2007 to 2016 were retrospectively accessed from the Humana database. Patients were categorized as those who filled opioid prescriptions within 3 months (OU), within 1 month (A-OU), between 1 and 3 months (C-OU), and never filled opioid prescriptions (N-OU) before surgery. Rates of opioid use were evaluated preoperatively and longitudinally tracked for each cohort. Prolonged opioid use was defined as continued opioid prescription filling at ≥3 months after surgery. Multiple logistic regression analysis was used to identify factors associated with opioid refills at 12 months after surgery.

RESULTS

There were 88,120 patients (53.7% female) who underwent arthroscopic meniscectomy, of whom 46.1% (n = 39,078) were N-OU. About a quarter (25.3%) of patients continued filling opioid prescriptions at 1 year postoperatively. In addition, opioid fill rate at 1 year was significantly greater in the OU group compared with the N-OU group with a relative risk of 2.89 (40.7% vs 14.1%; 95% confidence interval 2.81-2.98; P < .0001). Multiple logistic regression model identified C-OU (odds ratio 3.67; 95% confidence interval 3.53-3.82; P < .0001) as the strongest predictor of opioid use at 12 months postoperatively. Furthermore, male sex, A-OU, knee osteoarthritis, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, fibromyalgia, anxiety or depression, alcohol use disorder, and tobacco use (P < .02 for all) had significantly increased odds of opioid use at 12 months postoperatively. However, patients <40 years (P < .0001) had significantly decreased odds of opioid use 12 months postoperatively.

CONCLUSIONS

Preoperative opioid filling is a significant risk factor for opioid use at 12 months postoperatively. Male sex, preexisting knee osteoarthritis, and diagnosis of anxiety or depression were independent risk factors for opioid use 12 months following arthroscopic meniscectomy.

LEVEL OF EVIDENCE

Level-III, Retrospective Cohort Study.

Preoperative Opioid Prescription Filling Is a Risk Factor for Prolonged Opioid Use After Elbow Arthroscopy

PURPOSE

To (1) report the frequency of postoperative opioid prescriptions after elbow arthroscopy, (2) evaluate whether filling opioid prescriptions preoperatively placed patients at increased risk of requiring more opioid prescriptions after surgery, and (3) determine patient factors associated with postoperative opioid prescription needs.

METHODS

A national claims-based database was queried for patients undergoing primary elbow arthroscopy. Patients with prior total elbow arthroplasty or septic arthritis of the elbow were excluded. Patients who filled at least 1 opioid prescription between 1 and 4 months prior to surgery were defined as the preoperative opioid-use group. Monthly relative risk ratios for filling an opioid prescription were calculated for the first year after surgery. Multiple logistic regression analysis was performed to identify factors associated with opioid use at 3, 6, 9, and 12 months after elbow arthroscopy, with P < .05 defined as significant.

RESULTS

We identified 1,138 patients who underwent primary elbow arthroscopy. The preoperative opioid-use group consisted of 245 patients (21.5%), 61 of whom (24.9%) were still filling opioid prescriptions 12 months after surgery. The multivariate analysis determined that the preoperative opioid-use group was at increased risk of postoperative opioid prescription filling at 3 months (odds ratio [OR], 9.02; 95% confidence interval [CI], 5.98-13.76), 6 months (OR, 8.74; 95% CI, 5.57-13.92), 9 months (OR, 7.17; 95% CI, 4.57-11.39), and 12 months (OR, 6.27; 95% CI, 3.94-10.07) after elbow arthroscopy. Patients younger than 40 years exhibited a decreased risk of postoperative opioid prescription filling at 3 months (OR, 0.49; 95% CI, 0.25-0.91), 6 months (OR, 0.19; 95% CI, 0.06-0.50), 9 months (OR, 0.48; 95% CI, 0.22-0.97), and 12 months (OR, 0.44; 95% CI, 0.19-0.94) after surgery.

CONCLUSIONS

Preoperative opioid filling, fibromyalgia, and psychiatric illness are associated with an increased risk of prolonged postoperative opioid after elbow arthroscopy. Patient age younger than 40 years and chronic obstructive pulmonary disease are associated with a decreased risk of postoperative opioid prescription filling within the first postoperative year.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Validation of a novel hip arthroscopy simulator: establishing construct validity

Hip arthroscopy (HA) is technically demanding and associated with a prolonged learning curve. Recently, arthroscopic simulators have been developed to anatomically model various joints including the knee, shoulder and hip. The purpose of this study is to validate a novel HA simulator. Twenty trainees and one sports medicine fellowship-trained orthopaedic surgeon at a single academic institution were recruited to perform a diagnostic HA procedure using the VirtaMed ArthroS hip simulator. Trainee characteristics, including level of training, general arthroscopy experience and hip specific arthroscopy experience, were gathered via questionnaire. For the purpose of this study, participants were categorized as novice (<25), intermediate (25–74) or experienced (≥75) based on the number of prior arthroscopies performed. Various performance metrics, including composite score, time and camera path length were recorded for each attempt. Metrics were analyzed categorically using ANOVA tests with significance set to P < 0.05. Composite performance score in the novice cohort was 114.5 compared with 146.4 and 151.5 in the intermediate and experienced cohorts (P = 0.0019), respectively. Novice arthroscopists performed the simulated diagnostic arthroscopy procedure in an average time of 321 s compared with 202 s and 181 s in the intermediate and experienced cohorts (P < 0.002), respectively. Cartilage damage and simulator safety score did not differ significantly between groups (P = 0.775). Simulator composite score and procedure time showed strong correlation with year of training (r = 0.65 and −0.70, respectively) and number of arthroscopies performed (r = 0.65 and −0.72). The ArthroS hip simulator shows good construct validity and performance correlates highly with total number of arthroscopic cases reported during training.

Anatomic Syndesmotic and Deltoid Ligament Reconstruction with Flexible Implants: A Technique Description

The optimal fixation method for unstable syndesmosis (SYN) injuries remains a matter of debate between rigid screw fixation that stabilizes all three components of the syndesmosis but prohibits any motion, and flexible implants stabilizing by compression along the axis of the interosseous ligament. More recently additional repairs of the anterior or posterior SYN ligaments have been explored both clinically and biomechanically. The role for deltoid ligament (DL) repair or reconstruction in the setting of SYN injury remains controversial. However, the DL is increasingly recognized as having an important contribution to rotational stability of the ankle. A method of treatment is presented for unstable SYN injuries with flexible implants. An anatomic approach to reconstructing the DL with specific augmentation of the anterior and posterior bands of the deep deltoid ligament (DDL) is described for immediate restoration of medial ankle rotational stability. Level of Evidence: V.

Intra-Articular Pathology Associated with Acute and Chronic Anterior Cruciate Ligament Reconstruction

BACKGROUND

Concomitant meniscal and chondral pathology is common at the time of anterior cruciate ligament reconstruction (ACL-R). The purpose of the present study was to report the prevalence of concomitant intra-articular pathology for patients undergoing acute or chronic anterior cruciate ligament reconstruction.

METHODS

This study represents a prospective, consecutively collected cohort of 255 patients undergoing both primary and revision ACL-R between January 2012 and December 2014 at a single institution. The cohort was divided into an acute surgical group, defined as surgery within six weeks of injury, and a chronic surgical group, greater than six weeks removed from injury. The median time from injury to surgery for the entire cohort was 37 days (range: 4 days to 855 days). Variables of interest included patient demographic characteristics, concomitant meniscal and chondral pathology, and meniscus treatment.

RESULTS

Patients treated in the chronic setting were slightly older (28.7 ± 11.6 years vs. 23.1 ± 8.6 years, P=0.001), had a higher prevalence of complex tears of the medial meniscus (37.2% vs. 7.7%, P=0.012) and cartilage injury (16.5% vs. 7.8%, P=0.03). After excluding revision ACL-R procedures, complex medial meniscus tears in chronic ACL-R were higher than in acute ACL-R (medial= 27.3% vs. 3.0%, P=0.022), however when age was considered, these tears were no longer more frequent than in the acute setting (P=0.056). Similarly, the prevalence of cartilage injury was equivalent between groups after correcting for age (P=0.167). Among primary ACL-R, there were more medial meniscus repairs in the acute surgical group compared to the chronic group (60.6% vs. 24.2%, P=0.003). After excluding complex tears, medial meniscus repair rates were no longer performed more frequently in patients undergoing acute ACL-R (59.4% vs. 33.3%, P=0.054).

CONCLUSIONS

Data from this prospective cohort suggest that with increasing time from ACL injury to ACL-R, medial meniscus pathology increases, with a lower likelihood of meniscal repair in all patients undergoing ACL-R. However, this finding is no longer statistically significant when considering only patients undergoing primary ACL-R. Age appears to play an important role in whether concomitant pathology develops following ACL rupture. Given these findings, early intervention may increase the ability to repair medial meniscus tears in the setting of ACL-R, but this conclusion is less supported in primary ACL-R.Level of Evidence: II.

Does Patient Positioning and Portal Placement for Arthroscopic Subtalar Arthrodesis Matter?

Category:

Arthroscopy

Introduction/Purpose:

Arthroscopic subtalar joint arthrodesis was first described over two decades ago. The procedure was originally performed with the patient in the lateral decubitus or supine position using anterolateral and posterolateral portals based on the fibula. More recently, several authors have advocated for prone positioning utilizing posteromedial and posterolateral portals. Proponents of the prone position cite improved intra-articular visualization with limited need for traction and more thorough preparation of the posterior facet. Multiple studies have compared arthroscopic to open subtalar arthrodesis and demonstrated similar fusion rates, lower morbidity, and a high level of patient satisfaction with the arthroscopic procedure. To our knowledge, this is the first study investigating how patient positioning and portal placement affects outcomes and morbidity for the arthroscopic procedure.

Methods:

A systematic review was performed according to PRISMA guidelines utilizing PubMed and Embase. All original studies with reported complication rates for arthroscopic subtalar arthrodesis were included. Two independent reviewers collected patient demographic data, operative positioning, complications, and outcomes including time to fusion and American Orthopaedic Foot and Ankle Society (AOFAS) scores. Patients were placed into the prone group if they were positioned prone with posterior portals or the lateral group if they underwent lateral portal placement. The rate of complications related to portal placement, nonunion rate, rate of painful hardware, and rate of revision were also recorded. The proportions of patients with specific complications in each group were determined and transformed using the Freeman-Tukey double-arcsine method to stabilize variances. Heterogeneity across studies was present as determined using the Q and I2 statistics or likelihood ratio test. Inverse-variance weighted random-effects models were used to evaluate the pooled estimates using R software.

Results:

A total of 484 feet in 468 patients with a mean follow-up of 36.1 months were included for analysis. Thirteen studies examined patients in the prone position (n=302) and seven articles looked at lateral portals (n=182). Mean AOFAS scores improved from 46.3 to 81.6 following surgery. Fusion was seen in 95.8% of feet at a mean of 10.9 weeks. The total complication rate was similar (p=0.620) between the prone (18.2%) and lateral (17.6%) groups. There was no difference observed in the rate of complications secondary to portal placement (p=0.919), rate of painful hardware (p=0.534), and revision rate (p=0.400) between the two groups. The prone group sustained 20 nonunions (6.6%) which was significantly more than the 2 nonunions (1.1%) found in the lateral group (p=0.039).

Conclusion:

Arthroscopic subtalar arthrodesis is an effective treatment option for subtalar joint pathology. We found a higher rate of nonunion when the patient is positioned prone and the arthroscopic portals are placed posteriorly. There was no difference in the rate of nerve/tendon injury, painful hardware, and revision surgery. AOFAS scores were improved regardless of portal placement. Limitations of our study include the variability in fusion hardware and use of bone graft for fusion augmentation between studies. We also were unable to account for surgeon experience, operative volume, and comfort level with the procedure. Further large scale prospective studies are warranted.

Comparison of Short-term Complications After Rotator Cuff Repair: Open Versus Arthroscopic

PURPOSE

To define and compare the incidence and risk factors for short-term complications after arthroscopic and open rotator cuff repair (RTCR), and to identify independent risk factors for complications after RTCR.

METHODS

All patients who underwent open or arthroscopic RTCR from 2005 to 2013 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Short-term complications were categorized as surgical, medical, mortality, and unplanned 30-day readmission. Univariate analysis allowed the comparison of patient demographics and comorbidities. Propensity score matching was used to control for demographic differences between arthroscopic and open RTCR patient groups. Independent risk factors for complication were identified using multivariate logistic regression.

RESULTS

Overall, 11,314 RTCRs were identified (24% open, 76% arthroscopic). The mean operative time for open RTCR was 78 minutes compared with 91 minutes for arthroscopic repairs (P < .001). The overall complication rate was 1.3%, with the highest complication unplanned return to the operating room (41 patients, 0.36%). The 30-day readmission was 1.16% (76/6,560 patients) and the mortality rate was 0.03% (3 patients). Total 30-day complications in the propensity-score-matched patient group were higher after open versus arthroscopic repair (1.79% vs 1.17%; P = .006). The overall infection rate after RTCR was 0.56%, with deep wound infection higher in the open repair patient group (P = .003). Multivariate analysis identified age >65 years (odds ratio [OR] 1.6; 95% confidence interval [CI] 1.2-2.3), operative time >90 minutes (OR 1.5; CI 1.1-2.1), and open RTCR (OR 1.6; CI 1.1-2.3) as independent risk factors for complications.

CONCLUSIONS

Short-term complications after RTCR are rare. Total complications are higher after open RTCR in propensity-matched patient groups and in multivariate analysis. Risk factors for complications include patient age >65, operative time >90 minutes, and open repair. Open RTCR is associated with an increased risk of surgical infections.

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.

Outside-In vs. Anteromedial Portal Drilling During Primary ACL Reconstruction: Comparison at Two Years

BACKGROUND

Anteromedial (AM) and outside-in (OI) are two commonly used techniques for drilling the femoral tunnel during anterior cruciate ligament reconstruction (ACLR). The purpose of this study was to compare clinical and radiographic outcomes of patients undergoing primary ACLR using either AM or OI femoral drilling with minimum two year follow-up.

METHODS

Overall, 138 prospectively enrolled patients undergoing primary ACLR underwent AM or OI femoral drilling. Patients were categorized by femoral drilling technique and were evaluated pre-operatively as well as at six weeks and two years post-operatively. Outcomes scores were collected at each visit using SF-36 PCS and MCS components, KOOS, and the Knee Activity Rating Scale. Complications, including graft failure, stiffness requiring manipulation under anesthesia, and revision surgery were also collected.

RESULTS

Overall, 47 (34.1%) patients underwent AM femoral drilling and 91 (65.9%) patients underwent OI femoral drilling. Univariate analysis revealed no difference in pre-operative outcomes with the exception of the AM group having higher KOOS Knee Pain (p=0.023) and WOMAC Pain (p=0.036) scores. Postoperatively, OI femoral tunnels had a higher radiographic coronal angle (68.8°±8.6° vs 51.4°±11.3°; p<0.001) and knee extension (1.2°±2.7 vs 2.9°±4.0°; p=0.010). There were no differences in knee flexion, complications, or graft failure. Postoperatively, the AM group had higher KOOS ADL and WOMAC Functional (85 vs. 79 ,p=0.030) scores at the six week mark, although these differences did not meet the minimal clinically importance difference1. Graft failure at two years were similar in the AM and OI groups (8.5% vs. 6.6%, p=0.735). Multivariate analysis showed no clinical outcome differences between AM and OI techniques.

CONCLUSIONS

ACL reconstruction using the AM technique yielded lower radiographic coronal tunnel angle and slightly decreased knee extension. The theoretical risk of graft failure secondary to higher coronal angle of the graft as it passes around a sharper femoral tunnel aperture was not observed. Additionally, differences in pre-operative KOOS Knee pain existed but these differences were not significant postoperatively. We conclude no clinically relevant differences by two years in patients undergoing primary ACL reconstruction using either AM or OI femoral drilling techniques. Level of Evidence: Level II Prospective Comparative Study.

Double-bundle ACL reconstruction: novice surgeons utilizing computer-assisted navigation versus experienced surgeons

PURPOSE

Anatomic double-bundle ACL reconstruction presents a unique technical challenge for surgeons, requiring precise placement of multiple tunnels in a relatively small area. As the necessity of anatomic reconstruction has been stressed throughout the literature, developing a method to consistently improve the accuracy and precision of tunnel placement is essential. We aimed to investigate whether computer-assisted navigation allows novice surgeons to place double-bundle ACL tunnels with a similar degree of accuracy to experienced surgeons operating without computer assistance.

METHODS

A novice surgeon group comprising three medical students performed double-bundle ACL reconstruction using passive computer-assisted navigation in 11 cadaver knees. Their individual results were compared to those of three experienced orthopaedic surgeons, each performing the identical procedure without the use of computer-assisted navigation in 9 cadaver knees.

RESULTS AND CONCLUSION

There were no significant differences in placement of either the AM or PL tunnels on the tibial plateau between the novice surgeons using computer-assisted navigation and the experienced surgeons. However, on the lateral femoral condyle, the novice surgeons placed the AM and PL tunnels significantly more anterior along Blumensaat's line, on average, compared to the experienced surgeons.

A clinical and radiographic approach for establishing proper tibial tubercle transfer when using quad active femoral nerve stimulation

BACKGROUND

The tibial tubercle-trochlear groove measurement (TT-TG), which measures the lateral offset of the tibial tubercle relative to the trochlear groove of the femur, has been utilized as an intraoperative tool to help establish maximum patellofemoral congruency in patients who suffer from patellar instability. We have previously published our approach of establishing how far to transfer the tibial tubercle using intraoperative femoral nerve stimulation in order to achieve congruency from 0-30° of flexion. The technique and clinical outcomes have previously been published in this journal and elsewhere. Here we describe the use of the TT-TG distance to determine how far to transfer the tibial tubercle to achieve our goals and have found that it varies according to the clinical exam features.

PURPOSE

We intended to determine the effectiveness of using the preoperatively established TT-TG to predict the degree of intraoperative me- dialization of the tibial tubercle to achieve our goal of establishing dynamic congruency of the patella in the trochlear groove when using the previously described femoral nerve stimulation method of estimating dynamic tracking of the patella.

METHODS

From the study group of patients used in other publications, we examined 20 knees in 18 patients who had a history of recurrent lateral dislocations and underwent a Fulkerson tibial tubercle transfer. Each knee was dynamically assessed preoperatively by obtaining an MRI at 30° of flexion and complete hyperextension while voluntarily contracting their quadriceps. These were then compared to the intraoperative transfer of the tibial tubercle required to achieve maximum congruency when the femoral nerve was stimulated. We then looked at the preoperative TT-TG measurement to determine its role in predicting what was required at achieving congruency in the context of the quad active MRI findings.

RESULTS

Thirteen knees preoperatively demonstrated a positive J-sign defined as the patella subluxated greater than or equal to 5 mm lateral in full extension compared to 30° of flexion. In these patients, the TT-TG was accurate if the distance medialized was 1:1 with the measured TT-TG. In 7 out of the 20 knees, the patella demonstrated a false negative J-sign where the patella was radio- graphically subluxated at 30° of flexion as well as at hyperextension. In this group, the TT-TG underestimated the transfer required for congruency on average 5mm even when using the 1:1 ratio.

CONCLUSIONS

The preoperative use of the J-sign is of value when determining the role of the TT-TG measurement and estimating the distance required to intraoperatively achieve congruency when using the femoral nerve stimulation technique. Those that demonstrated a positive J-sign of 5mm or greater, a 1:1 ratio of TT-TG to medialization is most reliable at establishing congruency of the patellofemoral joint. Whereas, those that demonstrated a false negative J-sign even the 1:1 ratio remains inadequate at producing congruency and more medialization is required.

LEVEL OF EVIDENCE

Level III, Retrospective Observational/Comparative Study.

Case report: Quantitative MRI of tibial tubercle transfer during active quadriceps contraction

BACKGROUND

The evaluation of distal transfer procedures relies primarily on qualitative clinical findings. Although quantitative MRI measurements provide an objective supplement to qualitative clinical findings, an association between qualitative clinical findings and quantitative patellofemoral indices has yet to be established.

CASE DESCRIPTION

A 21-year-old man presented with frequent episodes of patellar dislocation. Clinical and radiographic findings identified the patient as a candidate for realignment. MR images were obtained with the quadriceps contracted at 30° flexion and in full extension preoperatively and postoperatively. The procedure eliminated the clinical J-sign, defined as lateral movement of the patella over the lateral femoral condyle during active leg extension, which was confirmed quantitatively using established patellofemoral indices in conjunction with MRI.

LITERATURE REVIEW

Movement of the patellofemoral joint is complex and dependent on many factors, including skeletal geometry, dynamic muscle action, and soft tissue restraints. Therefore, proper clinical and radiographic evaluation of patellar tracking requires observation during active quadriceps contraction. However, it is unclear whether there is any association between quantitative radiographic indices and qualitative clinical assessment during active quadriceps contraction.

PURPOSES AND CLINICAL RELEVANCE

We believe objective measurements are valuable in determining the radiographic assessment of patellar realignment procedures. Lateral patellar edge appears to quantify the clinical J-sign. The association between radiographic medialization of the patella and clinical improvement postoperatively in this patient warrants additional investigation in a larger group of patients with longer followup.

Quantifying the effects of extensor mechanism medializatlon procedures using MRI: a cadaver-based study

BACKGROUND

Patellofemoral joint kinematics are dependent on a variety of anatomical features. One of the most common causes of patellar instability is malalignment of the quadriceps extensor mechanism. The Southwick-Fulkerson osteotomy focuses on correcting malalignment of the quadriceps extensor mechanism through medialization of the tibial tubercle. MRI, in conjunction with established patellofemoral indices, allows quantitative evaluation of the patellofemoral joint during active quadriceps extension both pre- and postoperatively.

PURPOSE

This study aims to quantitatively evaluate the effects of extensor mechanism medialization procedures using established patellofemoral indices in order to establish a relationship between tubercle transfer distance and patellar tracking. It is believed that a 15mm medial transfer of the tibial tubercle will produce statistically significant changes in patellar tracking when evaluated during active quadriceps contraction.

METHODS

Four fresh-frozen cadavers underwent a modified Fulkerson osteotomy. The central quadriceps tendon was identified and traction was applied with a vector parallel to the femoral diaphysis using sutures, to simulate active quadriceps contraction. MRI images were obtained following Omm (control) and 15mm tibial tubercle medialization. Each knee was evaluated at 30, 20, 10, and 0 degrees of flexion.

RESULTS

Quantitative evaluation of patellar tracking during active quadriceps contraction detected significant changes in patellar translation following 15mm medial transfer of the tibial tubercle as compared to the control. The significantly reduced indices suggest reduced patellar lateralization and improved patellar tracking during the critical range of motion from 30 to 0 degrees of flexion.

CONCLUSIONS

The results of this study indicate that significant quantitative changes in patellar tracking occur following 15mm tibial tubercle medialization when evaluated during active quadriceps contraction using MRI in conjunction with established patellofemoral indices. These findings suggest that quantitative evaluation of patellar tracking may be a valuable pre- and postoperative tool when coupled with qualitative clinical findings.