Ability of Medial Patellofemoral Ligament Reconstruction to Overcome Lateral Patellar Motion in the Presence of Trochlear Flattening: A Cadaveric Biomechanical Study

2021 ◽  
pp. 036354652110410
Author(s):  
Amrit V. Vinod ◽  
Alex M. Hollenberg ◽  
Melissa A. Kluczynski ◽  
John M. Marzo
Keyword(s):  
Repeated Measures ◽  
Knee Flexion ◽  
Medial Patellofemoral Ligament ◽  
Operative Procedure ◽  
Biomechanical Study ◽  
Mpfl Reconstruction ◽  
Trochlear Groove ◽  
Sulcus Angle ◽  
Fresh Frozen ◽  
Patellar Stability

Background: Medial patellofemoral ligament (MPFL) reconstruction is an established operative procedure to restore medial restraining force in patients with patellar instability. In the setting of a shallow sulcus, it is unclear whether an isolated MPFL reconstruction is sufficient to restore patellofemoral stability. Hypothesis: Progressively increasing the sulcus angle would have an adverse effect on the ability of an MPFL reconstruction to restrain lateral patellar motion. Study Design: Controlled laboratory study. Methods: Seven fresh-frozen human cadaveric knees were harvested and prepared for experimentation. Each specimen was run through the following test conditions: native, lateral retinacular release, lateral retinacular repair, MPFL release, MPFL reconstruction, and MPFL reconstruction with trochlear flattening. Four 3-dimensional printed wedges (10°, 20°, 30°, and 40°) were created to insert beneath the native trochlea to raise the sulcus angle incrementally and simulate progressive trochlear flattening. For each test condition, the knee was positioned at 0°, 15°, 30°, and 45° of flexion, and the force required to displace the patella 1 cm laterally at 10 mm/s was measured. Group comparisons were made with repeated measures analysis of variance. Results: In the setting of an MPFL reconstruction, as the trochlear groove was incrementally flattened, the force required to laterally displace the patella progressively decreased. A 10° increase in the sulcus angle significantly reduced the force at 15° ( P = .01) and 30° ( P = .03) of knee flexion. The force required to laterally displace the patella was also significantly lower at all knee flexion angles after the addition of the 20°, 30°, and 40° wedges ( P≤ .05). Specifically, a 20° increase in the sulcus angle reduced the force by 29% to 36%; a 30° increase, by 35% to 43%; and a 40° increase, by 40% to 47%. Conclusion: Despite an MPFL reconstruction, the force required to laterally displace the patella decreased as the sulcus angle was increased in our cadaveric model. Clinical Relevance: An isolated MPFL reconstruction may not be sufficient to restore patellar stability in the setting of a shallow or flat trochlea. Patients with an abnormal sulcus angle may have recurrent instability postoperatively if treated with an isolated MPFL reconstruction.

scholarly journals A BIOMECHANICAL COMPARISON OF SUTURE ANCHOR VS. INTERFERENCE SCREW TECHNIQUE FOR PATELLAR FIXATION FOR MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION

2019 ◽  
Vol 7 (3_suppl) ◽  
pp. 2325967119S0010
Author(s):  
Dragomi Mijic ◽  
Sanar Yokhana ◽  
Kunal Kalra
Keyword(s):  
Repeated Measures ◽  
Medial Patellofemoral Ligament ◽  
Suture Anchor ◽  
Interference Screw ◽  
T Test ◽  
Mpfl Reconstruction ◽  
Initial Stiffness ◽  
Significant Difference ◽  
Load To Failure ◽  
Fresh Frozen

Background: There are numerous techniques for MPFL reconstruction, however, one single technique has not been proven to be superior to another. Suture anchor reconstruction has been shown to provide stable fixation while decreasing the risk of patellar fracture. The aim of the study was to compare the stiffness and clinical load to failure of two common MPFL reconstruction techniques. Our hypothesis was that there would be no significant difference in the stiffness and the clinical load to failure between the suture anchor and interference screw reconstructions. Methods: Eight pairs of fresh frozen cadaveric knees were randomized into two groups undergoing MPFL reconstruction using either a suture anchor technique (n=8) or an interference screw technique (n=8). Testing was performed at 0, 30, 60, and 90 degrees of flexion for the native knee, transected medial structures, and reconstructed MPFL. Next, the reconstructed MPFL specimens were tested until failure in 0 degrees of flexion. T test, One-Way ANOVA, and repeated measures of ANOVA were used for statistical analysis, P values less than 0.05 were considered significant. Results: The average stiffness for the suture anchor and interference screw reconstructions was 12.02 ± 3.96 N/mm and 14.21 ± 4.20 N/mm, respectively (t test, p = 0.27), while average clinical load to failure was 256.57 ± 54.1 N and 237.81 ± 23.82 N, respectively (t test, p = 0.38). There was no significant difference in stiffness between the suture anchor and interference screw techniques at 0, 30, and 60 degrees of flexion. Conclusions: The suture anchor and interference screw reconstruction techniques produce comparable stiffness for sub-failure testing at 0 and 30 degrees of flexion. For testing to failure, the initial stiffness for both reconstruction techniques have been shown to be concordant with previously published values for the native MPFL. Both reconstruction techniques provide greater ultimate failure loads than those reported for the native MPFL in previous studies. Clinical Relevance: Suture anchor reconstruction described in our study provides another reliable option for the reconstruction of the medial patellofemoral ligament. [Figure: see text]

scholarly journals Interference Screw Versus Suture Anchors for Femoral Fixation in Medial Patellofemoral Ligament Reconstruction: A Biomechanical Study

2021 ◽  
Vol 9 (3) ◽  
pp. 232596712198928
Author(s):  
Heath P. Gould ◽  
Nicholas R. Delaney ◽  
Brent G. Parks ◽  
Roshan T. Melvani ◽  
Richard Y. Hinton
Keyword(s):  
Medial Patellofemoral Ligament ◽  
Interference Screw ◽  
Biomechanical Study ◽  
Graft Fixation ◽  
Mpfl Reconstruction ◽  
Suture Anchors ◽  
Femoral Fixation ◽  
Significant Difference ◽  
Load To Failure ◽  
The Mean

Background: Femoral-sided graft fixation in medial patellofemoral ligament (MPFL) reconstruction is commonly performed using an interference screw (IS). However, the IS method is associated with several clinical disadvantages that may be ameliorated by the use of suture anchors (SAs) for femoral fixation. Purpose: To compare the load to failure and stiffness of SAs versus an IS for the femoral fixation of a semitendinosus autograft in MPFL reconstruction. Study Design: Controlled laboratory study. Methods: Based on a priori power analysis, a total of 6 matched pairs of cadaveric knees were included. Specimens in each pair were randomly assigned to receive either SA or IS fixation. After an appropriate reconstruction procedure, the looped end of the MPFL graft was pulled laterally at a rate of 6 mm/s until construct failure. The best-fit slope of the load-displacement curve was then used to calculate the stiffness (N/mm) in a post hoc fashion. A paired t test was used to compare the mean load to failure and the mean stiffness between groups. Results: No significant difference in load to failure was observed between the IS and the SA fixation groups (294.0 ± 61.1 vs 250.0 ± 55.9; P = .352), although the mean stiffness was significantly higher in IS specimens (34.5 ± 9.6 vs 14.7 ± 1.2; P = .004). All IS reconstructions failed by graft pullout from the femoral tunnel, whereas 5 of the 6 SA reconstructions failed by anchor pullout. Conclusion: In this biomechanical study using a cadaveric model of MPFL reconstruction, SA femoral fixation was not significantly different from IS fixation in terms of load to failure. The mean load-to-failure values for both reconstruction techniques were greater than the literature-reported values for the native MPFL. Clinical Relevance: These results suggest that SAs are a biomechanically viable alternative for femoral-sided graft fixation in MPFL reconstruction.

Clinical Comparison of Medial Patellofemoral Ligament Reconstruction With or Without Tibial Tuberosity Transfer for Recurrent Patellar Instability

2021 ◽  
pp. 036354652110377
Author(s):  
Jong-Min Kim ◽  
Jae-Ang Sim ◽  
HongYeol Yang ◽  
Young-Mo Kim ◽  
Joon-Ho Wang ◽  
...  
Keyword(s):  
Clinical Outcomes ◽  
Patellar Instability ◽  
Medial Patellofemoral Ligament ◽  
Tibial Tuberosity ◽  
Mpfl Reconstruction ◽  
Trochlear Groove ◽  
Functional Failure ◽  
Radiological Parameters ◽  
Recurrent Patellar Instability

Background: No clear guidelines or widespread consensus has defined a threshold value of tibial tuberosity–trochlear groove (TT-TG) distance for choosing the appropriate surgical procedures when additional tibial tuberosity osteotomy (TTO) should be added to augment medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar instability. Purpose: To compare the clinical outcomes between MPFL reconstruction and MPFL reconstruction with TTO for patients who have patellar instability with a TT-TG distance of 15 to 25 mm. Study Design: Cohort study; Level of evidence, 3. Methods: We retrospectively analyzed 81 patients who underwent surgical treatment using either MPFL reconstruction or MPFL reconstruction with TTO for recurrent patellar instability with a TT-TG distance of 15 to 25 mm; the mean follow-up was 25.2 months (range, 12.0-53.0 months). The patients were divided into 2 groups: isolated MPFL reconstruction (iMPFL group; n = 36) performed by 2 surgeons and MPFL reconstruction with TTO (TTO group; n = 45) performed by another 2 surgeons. Clinical outcomes were assessed using the Kujala score, Knee injury and Osteoarthritis Outcome Score, and Tegner activity score. Radiological parameters, including patellar height, TT-TG distance, patellar tilt, and congruence angle were compared between the 2 groups. Functional failure based on clinical apprehension sign, repeat subluxation or dislocation, and subjective instability and complications was assessed at the final follow-up. We also compared clinical outcomes based on subgroups of preoperative TT-TG distance (15 mm ≤ TT-TG ≤ 20 mm vs 20 mm < TT-TG ≤ 25 mm). Results: All of the clinical outcome parameters significantly improved in both groups at the final follow-up ( P < .001), with no significant differences between groups. The radiological parameters also showed no significant differences between the 2 groups. The incidence of functional failure was similar between the 2 groups (3 failures in the TTO group and 2 failures in the iMPFL group; P = .42). In the TTO group, 1 patient experienced a repeat dislocation postoperatively and 2 patients had subjective instability; in the iMPFL group, 2 patients had subjective instability. The prevalence of complications did not differ between the 2 groups ( P = .410). In the subgroup analysis based on TT-TG distance, we did not note any differences in clinical outcomes between iMPFL and TTO groups in subgroups of 15 mm ≤ TT-TG ≤ 20 mm and 20 mm < TT-TG ≤ 25 mm. Conclusion: MPFL reconstruction with and without TTO provided similar, satisfactory clinical outcomes and low redislocation rates for patients who had patellar instability with a TT-TG distance of 15 to 25 mm, without statistical difference. Thus, our findings suggest that iMPFL reconstruction is a safe and reliable treatment for patients with recurrent patellar dislocation with a TT-TG distance of 15 to 25 mm, without the disadvantages derived from TTO.

scholarly journals Is Diagnostic Arthroscopy at the Time of Medial Patellofemoral Ligament Reconstruction Necessary?

2020 ◽  
Vol 8 (8) ◽  
pp. 232596712094565
Author(s):  
Christopher L. Shultz ◽  
Samuel N. Schrader ◽  
Benjamin D. Packard ◽  
Daniel C. Wascher ◽  
Gehron P. Treme ◽  
...  
Keyword(s):  
Postoperative Pain ◽  
Knee Flexion ◽  
Medial Patellofemoral Ligament ◽  
Perioperative Complications ◽  
Mpfl Reconstruction ◽  
Tibial Tubercle ◽  
Level Of Evidence ◽  
Diagnostic Arthroscopy ◽  
Patient Reported ◽  
Arthroscopic Procedures

Background: Although medial patellofemoral ligament (MPFL) reconstruction is well described for patellar instability, the utility of arthroscopy at the time of stabilization has not been fully defined. Purpose: To determine whether diagnostic arthroscopy in conjunction with MPFL reconstruction is associated with improvement in functional outcome, pain, and stability or a decrease in perioperative complications. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who underwent primary MPFL reconstruction without tibial tubercle osteotomy were reviewed (96 patients, 101 knees). Knees were divided into MPFL reconstruction without arthroscopy (n = 37), MPFL reconstruction with diagnostic arthroscopy (n = 41), and MPFL reconstruction with a targeted arthroscopic procedure (n = 23). Postoperative pain, motion, imaging, operative findings, perioperative complications, need for revision procedure, and postoperative Kujala scores were recorded. Results: Pain at 2 weeks and 3 months postoperatively was similar between groups. Significantly improved knee flexion at 2 weeks was seen after MPFL reconstruction without arthroscopy versus reconstruction with diagnostic and reconstruction with targeted arthroscopic procedures (58° vs 42° and 48°, respectively; P = .02). Significantly longer tourniquet times were seen for targeted arthroscopic procedures versus the diagnostic and no arthroscopic procedures (73 vs 57 and 58 min, respectively; P = .0002), and significantly higher Kujala scores at follow-up were recorded after MPFL reconstruction without arthroscopy versus reconstruction with diagnostic and targeted arthroscopic procedures (87.8 vs 80.2 and 70.1, respectively; P = .05; 42% response rate). There was no difference between groups in knee flexion, recurrent instability, or perioperative complications at 3 months. Diagnostic arthroscopy yielded findings not previously appreciated on magnetic resonance imaging (MRI) in 35% of patients, usually resulting in partial meniscectomy. Conclusion: Diagnostic arthroscopy with MPFL reconstruction may result in findings not previously appreciated on MRI. Postoperative pain, range of motion, and risk of complications were equal at 3 months postoperatively with or without arthroscopy. Despite higher Kujala scores in MPFL reconstruction without arthroscopy, the relationship between arthroscopy and patient-reported outcomes remains unclear. Surgeons can consider diagnostic arthroscopy but should be aware of no clear benefits in patient outcomes.

Isolated Medial Patellofemoral Ligament Reconstruction Can Be an Effective Procedure in Patellofemoral Instability with Risk Factors

2019 ◽  
Vol 33 (10) ◽  
pp. 992-997 ◽  
Author(s):  
Fabian Blanke ◽  
Kathrin Watermann ◽  
Maximilian Haenle ◽  
Andreas Feitenhansl ◽  
Carlo Camathias ◽  
...  
Keyword(s):  
Risk Factors ◽  
Clinical Outcome ◽  
Medial Patellofemoral Ligament ◽  
Trochlear Dysplasia ◽  
Patellofemoral Instability ◽  
Effective Procedure ◽  
Mpfl Reconstruction ◽  
Trochlear Groove ◽  
Severe Problem ◽  
Outcome Scores

AbstractPatellofemoral instability is a severe problem in young and active patients. This pathology is influenced by ligamentous, bony, and neuromuscular parameters. The reconstruction of the medial patellofemoral ligament (MPFL) evolved to a primary procedure, but combined procedures were more frequently performed in the past years. However, additional operative procedures are associated with increased morbidity and no absolute indication can be identified in the literature. This study is intended to clarify whether addressing only ligamentous influence factors (MPFL) in chronic patellofemoral instability is sufficient to produce good clinical outcomes, or whether other risk factors influence the results negatively and should also be treated at some point. In 52 patients with chronic patellofemoral instability patellar height according to Caton-Deschamps, trochlear dysplasia according to Dejour, the leg axis, the femoral antetorsion, tibial tubercle (TT)–trochlear groove, and TT–posterior cruciate ligament distance were evaluated. All patients were treated with isolated MPFL reconstruction. After a minimum follow-up period of 24 months (24–36 months), the clinical outcome results were calculated using the scoring system according to Lysholm and Tegner. Correlation between clinical outcome scores and anatomic risk factors were calculated. The analysis was performed using a standard statistical software package (JMP version 12, SAS Institute, Cary, NC). The average postoperative Lysholm score increased significantly from 57.23 ± 19.9 to 85.9 ± 17.2 points (p < 0.0001) after isolated MPFL reconstruction. Moreover, the Tegner and Lysholm scores significantly improved both in patients without and with different risk factors postoperative. There were no significant differences in the outcome sores between the groups. Even the degree of trochlear dysplasia (types I–III) did not influence the results. Finally, there was no significant correlation found between all collected risk factors and the postoperative outcome scores. Isolated MPFL reconstruction can be an effective procedure in patients with patellofemoral instability and mild to moderate risk factors.

scholarly journals Patellar Kinematics, Part II: The Influence of the Depth of the Trochlear Groove in Subjects With and Without Patellofemoral Pain

2000 ◽  
Vol 80 (10) ◽  
pp. 965-973 ◽  
Author(s):  
Christopher M Powers
Keyword(s):  
Knee Flexion ◽  
Important Determinant ◽  
Knee Extension ◽  
Patellofemoral Pain ◽  
Trochlear Groove ◽  
Resonance Imaging ◽  
Patellar Tilt ◽  
Patellar Kinematics ◽  
Sulcus Angle ◽  
Kinematic Magnetic Resonance Imaging

Abstract Background and Purpose. A shallow intercondylar groove has been implicated as being contributory to abnormal patellar alignment. The purpose of this study was to assess the influence of the depth of the intercondylar groove on patellar kinematics. Subjects. Twenty-three women (mean age=26.8 years, SD=8.5, range=14–46) with a diagnosis of patellofemoral pain and 12 women (mean age=29.1 years, SD=5.0, range=24–38) without patellofemoral pain participated. Only female subjects were studied because of potential biomechanical differences between sexes. Methods. Patellar kinematics were assessed during resisted knee extension using kinematic magnetic resonance imaging. Measurements of medial and lateral patellar displacement and tilt were correlated with the depth of the trochlear groove (sulcus angle) at 45, 36, 27, 18, 9, and 0 degrees of knee flexion using regression analysis. Results. The depth of the trochlear groove was found to be correlated with patellar kinematics, with increased shallowness being predictive of lateral patellar tilt at 27, 18, 9, and 0 degrees of flexion and of lateral patellar displacement at 9 and 0 degrees of flexion (r=.51–.76). Conclusions and Discussion. The results of this study indicate that bony structure is an important determinant of patellar kinematics at end-range knee extension (0°–30°).

scholarly journals Lateral Translation of the Patella in MPFC Reconstruction: A Biomechanical Study of Three Surgical Techniques (210)

2021 ◽  
Vol 9 (10_suppl5) ◽  
pp. 2325967121S0031
Author(s):  
William Cregar ◽  
Hailey Huddleston ◽  
Elizabeth Shewman ◽  
Brian Cole ◽  
Adam Yanke
Keyword(s):  
Soft Tissue ◽  
Knee Flexion ◽  
Functional Disability ◽  
Articular Surface ◽  
Testing Machine ◽  
Surgical Techniques ◽  
Biomechanical Study ◽  
Mpfl Reconstruction ◽  
Tensile Testing Machine ◽  
Significant Difference

Objectives: Recurrent patellar instability (RPI) is a common knee disorder and can lead to chronic pain and functional disability. Surgically addressing recurrent patella instability has classically focused on reconstruction of the MPFL, which has widely become the standard of care either in isolation or concomitantly with other patellar realignment procedures. Complications following MPFL reconstruction include patellar fracture, articular surface penetration, and physeal injury in skeletally immature patients. In an effort to avoid these, other surgical techniques have been described. While these alternative MPFC reconstructions have anatomical support and the theoretical potential to reduce complications, it is unknown whether differences exist in lateral patellar translation and thus their effectiveness in adequately stabilizing the patella. The purpose of this study was to investigate whether differences exist in the ability to prevent lateral patellar translation between three distinct medial patellar stabilizing surgical procedures at varying knee flexion angles. Methods: Six cadaveric knee specimens were dissected, potted, and placed in a customized jig for testing. The quadricep muscle groups were separated into three components and loaded with a total of 175 N in anatomic directions using a weighted pulley system. Lateral patellar displacement was measured at 0°, 10°, 20°, 30°, 45°, 60°, and 90° of knee flexion using a tensile testing machine with a 20 N lateral force applied to the patella. Each specimen was tested with the MPFC intact and sectioned, and after each of the three reconstruction techniques: medial patellofemoral ligament (MPFL) reconstruction, hybrid (proximal medial patellar restraints - PMPR) reconstruction, and medial quadriceps-tendon femoral (MQTFL) reconstruction. Statistical analysis used the Friedman and Wilcoxon rank sum tests due to non-normally distributed data. Results: There was significantly increased lateral patellar displacement following MPFC sectioning when compared to the intact state in early degrees of flexion (10° to 30°) (p<0.05). All three reconstruction groups adequately restored patella stability and reduced lateral patellar displacement following medial soft tissue sectioning by 42%, 41% and 33% following MPFL, Hybrid and MQTFL reconstruction, respectively, from 0° to 30° of knee flexion (p<0.05 for each reconstruction group). When compared to the native, intact medial restraints group, all three reconstruction groups demonstrated reduced patella translation at full knee extension, while the MPFL and Hybrid reconstruction groups additionally demonstrated significant reduction of patella translation at 10° of flexion as well (p<0.05). When comparing patella displacement between reconstruction groups, no significant difference was observed at any degrees of flexion between the three groups. Conclusions: This biomechanical cadaveric study demonstrates the efficacy of three different MPFC reconstruction techniques in restoring patella stability following MPFC sectioning, especially at lower knee flexion angles where the medial soft tissue restraints play a more important role. Although all three reconstruction groups demonstrated less patella translation than the native MPFL intact knee, MPFL reconstruction appears to provide the most robust patella stabilization, whereas MQTFL reconstruction may be the most forgiving construct. Future clinical studies are needed to investigate the clinical correlation of these findings.

The Medial Patellofemoral Ligament Is a Dynamic and Anisometric Structure: An In Vivo Study on Length Changes and Isometry

2019 ◽  
Vol 47 (7) ◽  
pp. 1645-1653 ◽  
Author(s):  
Willem A. Kernkamp ◽  
Cong Wang ◽  
Changzou Li ◽  
Hai Hu ◽  
Ewoud R.A. van Arkel ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Medial Patellofemoral Ligament ◽  
Length Change ◽  
High Rate ◽  
Mpfl Reconstruction ◽  
Full Extension ◽  
3 Dimensional ◽  
Technical Errors ◽  
Length Changes

Background: Medial patellofemoral ligament (MPFL) reconstruction is associated with a high rate of complications, including recurrent instability and persistent knee pain. Technical errors are among the primary causes of these complications. Understanding the effect of adjusting patellofemoral attachments on length change patterns may help surgeons to optimize graft placement during MPFL reconstruction and to reduce graft failure rates. Purpose: To determine the in vivo length changes of the MPFL during dynamic, weightbearing motion and to map the isometry of the 3-dimensional wrapping paths from various attachments on the medial femoral epicondyle to the patella. Study Design: Descriptive laboratory study. Methods: Fifteen healthy participants were studied with a combined computed tomography and biplane fluoroscopic imaging technique during a lunge motion (full extension to ~110° of flexion). On the medial femoral epicondyle, 185 attachments were projected, including the anatomic MPFL footprint, which was divided into 5 attachments (central, proximal, distal, posterior, and anterior). The patellar MPFL area was divided into 3 possible attachments (proximal, central, and distal). The length changes of the shortest 3-dimensional wrapping paths of the various patellofemoral combinations were subsequently measured and mapped. Results: For the 3 patellar attachments, the most isometric attachment, with an approximate 4% length change, was located posterior and proximal to the anatomic femoral MPFL attachment, close to the adductor tubercle. Attachments proximal and anterior to the isometric area resulted in increasing lengths with increasing knee flexion, whereas distal and posterior attachments caused decreasing lengths with increasing knee flexion. The anatomic MPFL was tightest in extension, decreased in length until approximately 30° of flexion, and then stayed near isometric for the remainder of the motion. Changing both the femoral and patellar attachments significantly affected the length changes of the anatomic MPFL ( P < .001 for both). Conclusion: The most isometric location for MPFL reconstruction was posterior and proximal to the anatomic femoral MPFL attachment. The anatomic MPFL is a dynamic, anisometric structure that was tight in extension and early flexion and near isometric beyond 30° of flexion. Clinical Relevance: Proximal and anterior MPFL tunnel positioning should be avoided, and the importance of anatomic MPFL reconstruction is underscored with the results found in this study.

Comparison of Ligament Isometry and Patellofemoral Contact Pressures for Medial Patellofemoral Ligament Reconstruction Techniques in Skeletally Immature Patients

2020 ◽  
Vol 48 (14) ◽  
pp. 3557-3565
Author(s):  
Sheena R. Black ◽  
Kathleen N. Meyers ◽  
Joseph T. Nguyen ◽  
Daniel W. Green ◽  
Jacqueline M. Brady ◽  
...  
Keyword(s):  
Medial Patellofemoral Ligament ◽  
Pressure Sensors ◽  
Contact Forces ◽  
Mpfl Reconstruction ◽  
Equation Modeling ◽  
Trochlear Groove ◽  
Skeletally Immature ◽  
Patellar Kinematics ◽  
Femoral Physis ◽  
Skeletally Immature Patient

Background: Adult medial patellofemoral ligament (MPFL) reconstruction techniques are not appropriate for the skeletally immature patient given the proximity of the distal femoral physis. Biomechanical consequences of reconstructions aimed at avoiding the physis have not been adequately studied. Purpose: To quantify the biomechanical effects of MPFL reconstruction techniques intended for skeletally immature patients. Study Design: Controlled laboratory study Methods: Four MPFL reconstruction techniques were evaluated using a computationally augmented cadaveric model: (1) Schoettle point: adult-type reconstruction; (2) epiphyseal: socket distal to the femoral physis; (3) adductor sling: graft wrapped around the adductor tendon; (4) adductor transfer: adductor tendon transferred to patella. A custom testing frame was used to cycle 8 knees for each technique from 10° to 110° of flexion. Patellofemoral kinematics were recorded using a motion camera system, contact stresses were recorded using Tekscan pressure sensors, and MPFL length was computed using an inverse kinematics computational model. Change in MPFL length, patellar facet forces, and patellar kinematics were compared using generalized estimating equation modeling. Results: Schoettle point reconstruction was the most isometric, demonstrating isometry from 10° to 100°. The epiphyseal technique was isometric until 60°, after which the graft loosened with increasing flexion. The adductor sling and adductor transfer techniques were significantly more anisometric from 40° to 110°. Both grafts tightened with knee flexion and resulted in significantly more lateral patellar tilt versus the intact state in early flexion and significantly higher contact forces on the medial facet versus the epiphyseal technique in late flexion. Conclusion: In this cadaveric simulation, the epiphyseal technique allowed for a more isometric ligament until midflexion, when the patella engaged within the trochlear groove. The adductor sling and adductor transfer grafts became tighter in flexion, resulting in potential loss of motion, pain, graft stretching, and failure. Marginal between-condition differences in patellofemoral contact mechanics and patellar kinematics were observed in late flexion. Clinical Relevance: In the skeletally immature patient, using an epiphyseal type MPFL reconstruction with the femoral attachment site distal to the physis results in a more isometric graft compared with techniques with attachment sites proximal to the physis.

scholarly journals Identifying Patients With Patella Alta and/or Severe Trochlear Dysplasia Through the Presence of Patellar Apprehension in Higher Degrees of Flexion

2020 ◽  
Vol 8 (6) ◽  
pp. 232596712092548
Author(s):  
Matthew Colatruglio ◽  
David C. Flanigan ◽  
Sarah Harangody ◽  
Robert A. Duerr ◽  
Christopher C. Kaeding ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Patellar Instability ◽  
Trochlear Dysplasia ◽  
Patella Alta ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
Type B ◽  
Level Of Evidence ◽  
Sulcus Angle ◽  
Recurrent Patellar Instability

Background: Recurrent patellar instability is frequently treated surgically with reconstruction of the medial patellofemoral ligament (MPFL). Patients with significant patella alta, trochlear dysplasia, and/or an elevated tibial tubercle–trochlear groove (TT-TG) distance may benefit from a concurrent bony procedure such as tibial tubercle osteotomy or trochleoplasty. The indications to perform such procedures are traditionally based on imaging criteria but remain controversial. Patellar apprehension is common in patients with patellar instability but typically resolves in higher degrees of knee flexion. Hypothesis: The persistence of patellar apprehension at greater than 60° of knee flexion is associated with patella alta, an increased TT-TG distance, and trochlear dysplasia. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 76 patients with recurrent patellar instability were prospectively identified in a sports medicine clinic. Patellar apprehension was evaluated in each patient. Apprehension was defined as the patient reporting that the patella felt unstable to lateral patellar translation. Apprehension was first assessed at full knee extension and repeatedly assessed as the knee was flexed in 10° intervals, as measured using a goniometer. The degree of flexion at which patellar apprehension disappeared was recorded. Plain radiographs and magnetic resonance imaging (MRI) scans were obtained for all patients. Patellar height was assessed with the Caton-Deschamps (CD) index, and trochlear morphology was assessed through measurements of the sulcus angle and depth on MRI and classified using the Dejour classification system. Imaging measurements of patients in whom apprehension resolved by 60° of knee flexion were compared with measurements for those with apprehension that persisted deeper into flexion. Results: Apprehension resolved by 60° of flexion in 56 patients and persisted into deeper flexion in 20 patients. The patients with a delayed resolution of apprehension demonstrated a higher CD index; elevated TT-TG distance; increased sulcus angle; decreased sulcus depth; and higher incidence of Dejour type B, C, or D dysplasia (all P < .05). Of the 20 patients with a delayed resolution of apprehension, 18 had either Dejour type B, C, or D dysplasia or a CD index of at least 1.30. A delayed resolution of apprehension was present in 11 of the 16 patients with Dejour type B, C, or D dysplasia. Conclusion: Overall, 90% of patients with significant patella alta and the majority of patients with high-grade trochlear dysplasia demonstrated patellar apprehension that persisted beyond 60° of knee flexion. Additionally, 90% of patients with persistent apprehension had significant patella alta and/or trochlear dysplasia. Further work is needed to evaluate the utility of these findings to inform surgical decision-making in this population.

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