scholarly journals Clinical results after distal femoral osteotomies in patients with patellar maltracking

2017 ◽  
Vol 5 (4_suppl4) ◽  
pp. 2325967117S0014
Author(s):  
Jannik Frings ◽  
Tobias C. Drenck ◽  
Ralph Akoto ◽  
Arno Schmeling ◽  
Karl-Heinz Frosch
Keyword(s):  
Patellar Instability ◽  
Clinical Results ◽  
Individual Therapy ◽  
Mpfl Reconstruction ◽  
Lateral Release ◽  
Tibial Tubercle ◽  
Therapy Algorithm ◽  
Patellar Maltracking ◽  
Leg Axis ◽  
Torsional Osteotomy

Aims and Objectives: Few clinical trials analyze the results after distal femoral osteotomies (torsional and axial adjustment) for patellar maltracking with or without patellar instability. The purpose of the presented study is to capture the clinical results as well as the reluxation rate after torsional osteotomy or axial adjustment (Types 3d, 3e and 5 according to Frosch et al.). Materials and Methods: Between 2010 and 2015 294 cases of patellar instability and/or maltracking were treated in our hospital, 277 surgically. All patients were classified according to Frosch et al. and treated by the corresponding algorithm. 49 patients received a distal femoral osteotomy. Torsional angle and leg axis were radiologically measured in all patients. We used the common scoring systems and determined the redislocation rate. Results: Type 3e and 5 27 cases (18 patients, average 22y) torsional osteotomies were performed. 21 of 27 cases were classified as type 3e (7%), 6 as type 5 (2%). 22 other cases (19 patients) with an average age of 27 years (14-46 years) were classified as type 3d (7,5% of all cases). 17 axial adjustments were performed, 4 isolated MPFL reconstructions and 1 osteotomy of the tibial tubercle. Average femoral antetorsion was 38,6° (±9,3°), die tibial torsion was 35,1° (±11,7°). The average deviation of the leg axis in the frontal plane was 5° (±2,4°) varus (n=9) and 2,8° (±2,9°) valgus (n=14). The mean TT-TG distance was 19,9 mm (±4,9 mm). Torsional osteotomy was combined with MPFL-reconstruction (n=19), tibial tubercle transfer (Ø12,6 mm, n=13) or axial correction (Ø4° varus, Ø6° valgus, n=13), 5 double osteotomies. Torsion was corrected by 13° femoral and 11° tibial on average. After 19 months VAS was 1.2, Kujala 78.8, a Lysholm 79.1, Tegner 4. Only one patient experienced a subluxation after a fall. No redislocation. 3d 7,5% (n=22) showed a mean axial deviation of 6,5° (±2,2°) valgus. Average TT-TG distance was 18,3 mm (±5,8 mm). We performed 15 closed-wedge varus distal femoral osteotomies (Ø6,8°±2,3°), combined with an Elmslie-Trillat (n=14) or Fulkerson procedure (n=1), MPFL reconstruction (n=15) or lateral release (n=1). 4 isolated MPFL reconstructions. One case of a pathological lateral slope with patellar instability was treated by double osteotomy (8° femoral to varus, 4° tibial to valgus). One tibial varisation (5,5°) with MPFL reconstruction and Elmslie-Trillat procedure. Tibial tubercle was medialized by 11 mm ±6,7 mm on average. 22 MPFL reconstructions were done. After average 33 months VAS was 2.3, Kujala 72, Lysholm 79, Tegner 4. No redislocation. Conclusion: Torsional and axis correcting osteotomies are suitable techniques to treat patellar instability or maltracking. Clinically the patients’ benefit is substantial. Consideration of additional procedures is crucial to success, a thorough analysis of all causal pathologies is mandatory. The results approve our individual therapy algorithm in the treatment of patellar instability and maltracking caused by torsional deformities or axis deviations.

scholarly journals INCREASED TIBIOFEMORAL ROTATION WITH INCREASING SEVERITY OF PATELLAR INSTABILITY

2020 ◽  
Vol 8 (4_suppl3) ◽  
pp. 2325967120S0023
Author(s):  
Kenneth M. Lin ◽  
Evan W. James ◽  
Lindsay Schlichte ◽  
Grace Wang ◽  
Daniel Green
Keyword(s):  
Patellar Instability ◽  
External Rotation ◽  
Intraclass Correlation ◽  
Mpfl Reconstruction ◽  
Tibial Tubercle ◽  
Tibial Rotation ◽  
Trochlear Groove ◽  
Clinical Effects ◽  
Tibiofemoral Rotation ◽  
The Relationship

Background: Tibiofemoral rotation (TFR), specifically external tibial rotation, has been recently identified as a potential contributing factor to patellar instability. However, no previous studies have explored the clinical effects of differing degrees of TFR in relation to patellar instability. Purpose and Hypothesis: The purpose of this study is to investigate the relationship between severity of instability with degree of TFR. Our hypothesis is that fixed or obligatory dislocators (FOD) are more likely to have increased external TFR (tibial external rotation compared to femur) than standard patellar instability (SPI) patients requiring medial patellofemoral ligament (MPFL) reconstruction, who will have similar or slightly increased external TFR compared to normal controls. Methods: A retrospective study was performed with patients from 3 cohorts from April 2009 to February 2019: FOD, SPI, and controls with normal magnetic resonance imaging (MRI) of the knee. All FOD patients from the study time frame were analyzed, while controls and SPI patients were randomly selected. Patients were included for age under 18 years and diagnosis corresponding to one of the three cohorts, and excluded for outside institution MRI, and previous MPFL reconstruction or tibial tubercle osteotomy. TFR was measured on preoperative axial MRI using the posterior femoral and tibial condylar lines (Figure 1). Tibial tubercle to trochlear groove distance (TT-TG) was measured. Intraclass correlation coefficient (ICC) was calculated among 3 measurers. Statistical analysis using ANOVA and t-test was performed with significance set at α=0.05. Results: A total of 57 patients were included, 19 in each cohort. Average age was 13.2 years (range 10-17 years), with 31 females (54%). ICC for TT-TG and TFR were 0.90 and 0.72, respectively. TT-TG differed between the controls and SPI patients (both P<0.001), and controls and FOD patients (P<0.001), but not between SPI and FOD patients (P=0.12). TFR differed among the three groups: 8.4° (SD 16.7°) external TFR in FOD, 1.6° (SD 5.4°) external TFR in SPI, and 2.5° (SD 5.8°) internal TFR in controls (P=0.0089). FOD patients had significantly greater external tibial rotation than the SPI group (P=0.047). Conclusions: The degree of TFR is correlated with severity of patellar instability, with greater external tibial rotation seen in FOD than SPI patients, while TT-TG was not different. Further information on the relationship of TFR and patellar instability will not only improve understanding of pathogenesis and prognosis, but may also direct surgical treatment strategies in refractory or severe cases. [Figure: see text][Figure: see text]

scholarly journals Return To Sport Following Stabilization Surgery For Recurrent Patellar Instability In Patients Undergoing Isolated Mpfll Reconstruction Vs. Combined Mpfl Reconstruction And Tibial Tubercle Osteotomy

2020 ◽  
Vol 8 (3_suppl2) ◽  
pp. 2325967120S0012
Author(s):  
Stephanie Joelle Swensen ◽  
Joseph Nguyen ◽  
William A. Marmor ◽  
Simone Gruber ◽  
Beth E. Shubin Stein
Keyword(s):  
Functional Outcomes ◽  
Patellar Instability ◽  
Return To Sport ◽  
Activity Level ◽  
Mpfl Reconstruction ◽  
Equation Modeling ◽  
Tibial Tubercle ◽  
Outcome Scores ◽  
Patellar Stability ◽  
Over Time

Objectives: Acute patellar instability is a common and disabling injury among young athletes and the risk of recurrence is as high as 80% in certain populations. The essential lesion of lateral patellar dislocations is MPFL rupture. However, bony risk factors for dislocation have also been identified, including patella alta, trochlear dysplasia, and a lateralized tibial tubercle. Significant debate exists regarding the optimal treatment due to the multifactorial nature of the pathology. Isolated MPFL reconstructions have demonstrated good functional outcomes within the literature. Failure to address bony malalignment has been proposed as a source of failure for these procedures. The addition of realignment techniques, such as tibial tubercle distalizations and medializations has been recommended to improve patellar stability in select patients. There is a paucity of literature on redislocation rates, return to sport, and functional outcomes after patellofemoral stabilization surgery. The purpose of the current study is to compare redislocation rates, return to sport, and functional outcomes between patients undergoing isolated MPFL reconstruction versus patients who have undergone MPFL and TTO as treatment for recurrent patellofemoral instability. It is hypothesized that patients who have undergone isolated MPFL reconstructions will have improved outcomes and return to sport rates compared to combined MPFL reconstruction and TTO. Methods: A retrospective chart review of prospectively collected data from 2014-2017 was conducted to identify consecutive athletes who underwent primary isolated MPFL reconstruction or MPFL reconstruction combined with TTO. Exclusion criteria included concomitant cruciate ligament surgery, multi-ligament surgery, and failed previous surgery. Patient information, including redislocation rate, radiographic data, sporting level, return to sport, previous dislocation rates, and subsequent surgeries were recorded. Generalized estimating equation modeling was used to analyze longitudinal outcome scores (Kujala, IKDC), activity level (HSS, Ped-FABS), and health-related quality of life (KOOS-PS, KOOS-QOL) collected at baseline, 1-year, and 2-year postoperatively. Results: A total of 100 patients were included in the study (71 MPFL; 29 MPFL+TTO). Redislocation rates were low for both MPFL and MPFL+TTO groups (1/70 and 1/28, respectively). No differences were found in reported incidence of post-op dislocation or subluxation (P=0.498 and 191, respectively). Both groups reported a high rate of RTS with MPFL at 87% and TTO at 89% (P>0.999). However, the ability to return to the same or higher level of RTS was significantly higher in MPFL patients (85%) versus TTO (57%) (P=0.009). And for those patients who were able to RTS, the time to RTS was significantly lower in MPFL patients (8.9 months) compared to TTO patients (13.5 months) (P<0.001). Both study groups had significant improvement over time in all functional outcome scores. Patients in the MPFL+TTO group consistently reported with worse functional scores at baseline. Conclusion: Patients undergoing MPFL reconstruction with or without correction of bony malalignment reported significant improvement over time with high return to sport rates and low recurrent dislocation rates. However, patients undergoing MPFL+TTO reported lower scores compared to MPFL patients at baseline and 2-years follow-up.

scholarly journals Revision Surgery in Permanent Patellar Dislocation in DiGeorge Syndrome

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Massimo Berruto ◽  
Andrea Parente ◽  
Paolo Ferrua ◽  
Stefano Pasqualotto ◽  
Francesco Uboldi ◽  
...  
Keyword(s):  
Digeorge Syndrome ◽  
Patellar Instability ◽  
Left Knee ◽  
Mpfl Reconstruction ◽  
Complex Case ◽  
Lateral Release ◽  
Specific Patient ◽  
Patellar Subluxation ◽  
History Of ◽  
One Year

A 29-year-old patient, suffering from DiGeorge syndrome, came to our attention with a history of persistent pain and patellar instability in the left knee after failure of arthroscopic lateral release and Elmslie-Trillat procedure. The patient was unable to walk without crutches and severely limited in daily living activities. Because of arthritic changes of the patellofemoral joint and the failure of previous surgeries it was decided to perform only an open lateral release and medial patellofemoral ligament (MPFL) reconstruction using a biosynthetic ligament in order to obtain patellofemoral stability. At one year post-op range of motion (ROM) was 0–120 with a firm end point at medial patellar mobilization; patella was stable throughout the entire ROM. All the scores improved and she could be able to perform daily activity without sensation of instability. Bilateral patellar subluxation and systemic hyperlaxity are characteristics of syndromic patients and according to literature can be also present in DiGeorge syndrome. MPFL reconstruction with lateral release was demonstrated to be the correct solution in the treatment of patellar instability in this complex case. The choice of an artificial ligament to reconstruct the MPFL was useful in this specific patient with important tissue laxity due to her congenital syndrome.

scholarly journals Increased Tibiofemoral Rotation with Increasing Severity of Patellar Instability in the Pediatric Population

2020 ◽  
Vol 8 (7_suppl6) ◽  
pp. 2325967120S0048
Author(s):  
Evan James ◽  
Alexandra Aitchison ◽  
Lindsay Schlichte ◽  
Grace Wang ◽  
Daniel Green ◽  
...  
Keyword(s):  
Patellar Instability ◽  
External Rotation ◽  
Intraclass Correlation ◽  
Mpfl Reconstruction ◽  
Tibial Tubercle ◽  
Tibial Rotation ◽  
Trochlear Groove ◽  
Clinical Effects ◽  
Tibiofemoral Rotation ◽  
The Relationship

Objectives: Tibiofemoral rotation (TFR), specifically external tibial rotation, has been recently identified as a potential contributing factor to patellar instability. However, no previous studies have explored the clinical effects of differing degrees of TFR in relation to patellar instability. The purpose of this study is to investigate the relationship between severity of instability with degree of TFR. Our hypothesis is that fixed or obligatory dislocators (FOD) are more likely to have increased external TFR (tibial external rotation compared to femur) than standard patellar instability (SPI) patients requiring medial patellofemoral ligament (MPFL) reconstruction, who will have similar or slightly increased external TFR compared to normal controls. Methods: A retrospective study was performed with patients from 3 cohorts from April 2009 to February 2019: FOD, SPI, and controls with normal magnetic resonance imaging (MRI) of the knee. All FOD patients from the study time frame were analyzed, while controls and SPI patients were randomly selected. Patients were included for age under 18 years and diagnosis corresponding to one of the three cohorts, and excluded for outside institution MRI, and previous MPFL reconstruction or tibial tubercle osteotomy. TFR was measured on preoperative axial MRI using the posterior femoral and tibial condylar lines (Figure 1). Tibial tubercle to trochlear groove distance (TT-TG) was measured. Intraclass correlation coefficient (ICC) was calculated among 3 measurers. Statistical analysis using ANOVA and t-test was performed with significance set at α=0.05. Results: A total of 57 patients were included, 19 in each cohort. Average age was 13.2 years (range 10-17 years), with 31 females (54%). ICC for TT-TG and TFR were 0.90 and 0.72, respectively. TT-TG differed between the controls and SPI patients (both P<0.001), and controls and FOD patients (P<0.001), but not between SPI and FOD patients (P=0.12). TFR differed among the three groups: 8.4° (SD 16.7°) external TFR in FOD, 1.6° (SD 5.4°) external TFR in SPI, and 2.5° (SD 5.8°) internal TFR in controls (P=0.0089). FOD patients had significantly greater external tibial rotation than the SPI group (P=0.047). Conclusions: The degree of TFR is correlated with severity of patellar instability, with greater external tibial rotation seen in FOD than SPI patients, while TT-TG was not different. Further information on the relationship of TFR and patellar instability will not only improve understanding of pathogenesis and prognosis, but may also direct surgical treatment strategies in refractory or severe cases.

scholarly journals Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability Regardless of the Tibial Tubercle Trochlear Groove Distance: Outcomes at 1 and 2 Years

2018 ◽  
Vol 6 (7_suppl4) ◽  
pp. 2325967118S0007
Author(s):  
Brandon J. Erickson ◽  
Joseph Nguyen ◽  
Katelyn Gasik ◽  
Jacqueline Brady ◽  
Beth E. Shubin Stein
Keyword(s):  
Patellar Instability ◽  
Medial Patellofemoral Ligament ◽  
Trochlear Dysplasia ◽  
Patellar Height ◽  
Mpfl Reconstruction ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
One Year ◽  
Recurrent Patellar Instability

Background: Several surgical options exist for treatment of recurrent patellar instability. The treatments can be divided into ligamentous and bony procedures. It is currently unclear which patients require a bony procedure in addition to a soft tissue reconstruction. Purpose: To report the one and two-year outcomes of patients following medial patellofemoral ligament (MPFL) reconstruction performed in isolation regardless of the patellar height, tibial tubercle trochlear groove distance (TT-TG) or trochlear dysplasia. Hypothesis:: Patients will have <5% re-dislocation rate and significant improvements in patient reported outcome measures (PROMs) following isolated MPFL reconstruction. Methods: All patients with recurrent patellar instability and without significant unloadable chondral defects, failed previous surgery or pain greater than or equal to 50% as their chief complaint, were prospectively enrolled beginning March of 2014. All patients underwent a primary, unilateral, isolated MPFL reconstruction regardless of concomitant bony pathology for treatment of recurrent patellar instability. Patients were followed at standard intervals. PROMs were collected at one year and two year follow up visits. Information on recurrent subjective instability, dislocations, and ability to return to sport (RTS) was recorded. TT-TG and patellar height (using the Caton-Deschamps index) were measured on magnetic resonance images. Results: Overall, 90 patients (77% female; average age 19.4 +/- 5.6 years) underwent a MPFL reconstruction from March 2014 to August 2017; 63 (70%) of whom reached one year follow up, and 35 of these patients (39%) reached 2-year follow-up. No patient experienced a redislocation; 96% of patients at one year and 100% of patients at two years had no subjective patellofemoral instability. RTS rates at one and two years were 59% and 75% respectively. No patient experienced a complication at one year. All patients had a clinically and statistically significant improvement from baseline to 1-year follow-up in the following PROMs: Knee injury and Osteoarthritis Outcome Score Quality of Life (KOOS QOL) (32.7 to 72.0; p<0.001), International Knee Documentation Committee (IKDC) (51.4 to 82.6; p<0.001) Kujala (62.2 to 89.5; p<0.001), and all general health PROM. No clinically and statistically significant change was seen between 1- and 2-year follow-ups in all outcome scores (all p>0.05). A non-statistically significant increase was seen in sporting activity of the Pediatric Functional Activity Brief Scale (Pedi-FABS) (13.9 to 16.7 p=0.292) at 2 years. Average patient satisfaction was 9.3 of 10 (10 being most satisfied) at 1- and 2-year follow-up. Average TT-TG was 15.1 +/- 4.0. Average patellar height was 1.25 +/- 0.17. Conclusion: Isolated MPFL reconstruction is an effective treatment for patellar instability and provides significant improvements in PROMs with a low redislocation/instability rate at early 1 and 2 year follow up, regardless of bony pathologies including TT-TG, Caton-Deschamps Index and trochlear dysplasia. The goal of this ongoing prospective study is to follow these patients out for 5 to 10 years to assess what radiologic and physical examination factors predict failure of isolated MPFL reconstruction.

Clinical Outcomes and Predictive Factors for Failure With Isolated MPFL Reconstruction for Recurrent Patellar Instability: A Series of 211 Reconstructions With a Minimum Follow-up of 3 Years

2019 ◽  
Vol 47 (6) ◽  
pp. 1323-1330 ◽  
Author(s):  
Elliot Sappey-Marinier ◽  
Bertrand Sonnery-Cottet ◽  
Padhraig O’Loughlin ◽  
Herve Ouanezar ◽  
Levi Reina Fernandes ◽  
...  
Keyword(s):  
Patellar Instability ◽  
Trochlear Dysplasia ◽  
Patella Alta ◽  
Mpfl Reconstruction ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
Kujala Score ◽  
The Mean ◽  
Recurrent Patellar Instability

Background: Reconstruction of the medial patellofemoral ligament (MPFL) is widely acknowledged as an integral part of the current therapeutic armamentarium for recurrent patellar instability. The procedure is often performed with concomitant bony procedures, such as distalization of the tibial tuberosity or trochleoplasty in the case of patella alta or high-grade trochlear dysplasia, respectively. At the present time, few studies have evaluated the clinical effectiveness of MPFL reconstruction as an isolated intervention. Purpose: To report the clinical outcomes of isolated MPFL reconstruction in cases of patellar instability and to identify predictive factors for failure. Study Design: Case series; Level of evidence, 4. Methods: A retrospective analysis of prospectively collected data was performed, including all patients who had undergone isolated MPFL reconstruction between January 2008 and January 2014. Preoperative assessment included the Kujala score, assessment of patellar tracking (“J-sign”), and radiographic features, such as trochlear dysplasia according to Dejour classification, patellar height with the Caton-Deschamps index (CDI), tibial tubercle–trochlear groove distance, and patellar tilt. The Kujala score was assessed postoperatively. Failure was defined by a postoperative patellar dislocation or surgical revision for recurrent patellar instability. Results: A total of 239 MPFL reconstructions were included; 28 patients (11.7%) were uncontactable and considered lost to follow-up. Thus, 211 reconstructions were analyzed with a mean follow-up of 5.8 years (range, 3-9.3 years). The mean age at surgery was 20.6 years (range, 12-48 years), and 55% of patients were male. Twenty-seven percent of patients had a preoperative positive J-sign, and 93% of patients had trochlear dysplasia (A, 47%; B, 25%; C, 15%; D, 6%). The mean CDI was 1.2 (range, 1.0-1.7); mean tibial tubercle–trochlear groove distance, 15 mm (range, 5-30 mm); and mean patellar tilt, 23° (range, 9°-47°). The mean Kujala score improved from 56.1 preoperatively to 88.8 ( P < .001). Ten failures were reported that required surgical revision for recurrent patellar instability (4.7%). Uni- and multivariate analyses highlighted 2 preoperative risk factors for failure: patella alta (CDI ≥1.3; odds ratio, 4.9; P = .02) and preoperative positive J-sign (odds ratio, 3.9; P = .04). Conclusion: In cases of recurrent patellar instability, isolated MPFL reconstruction would appear to be a safe and efficient surgical procedure with a low failure rate. Preoperative failure risk factors identified in this study were patella alta with a CDI ≥1.3 and a preoperative positive J-sign.

scholarly journals Isolated MPFL reconstruction for recurrent lateral patellar instability in patients with TT-TG distance <25 mm: A calculated safe risk!

2021 ◽  
Vol 0 ◽  
pp. 1-7
Author(s):  
Sumant Chacko Verghese ◽  
Santosh K. Sahanand ◽  
Nikhil Joseph Martin ◽  
Abhay Harsh Kerketta ◽  
Prashanth Chalasani ◽  
...  
Keyword(s):  
Functional Outcome ◽  
Patellar Instability ◽  
Trochlear Dysplasia ◽  
Treatment Algorithm ◽  
Patella Alta ◽  
Mpfl Reconstruction ◽  
Long Term Results ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
Study Population

Objectives: The objectives of the study were to describe the surgical technique of our modification of isolated medial patellofemoral ligament (MPFL) reconstruction, in patients with patellar instability. As per literature, isolated MPFL reconstruction is advocated if tibial tubercle-trochlear groove (TTTG) <20 mm. Our study proposes isolated MPFL reconstruction in patients with TT-TG <25 mm and aims to determine any predisposing anatomic variants to aid in the treatment algorithm. Materials and Methods: A retrospective analysis of 52 patients with patellar instability (TT-TG <25 mm), who underwent isolated MPFL reconstruction was undertaken. The study population was divided into two groups; TT-TG <20 mm and TT-TG = 20–24 mm. Both groups were assessed radiologically and on the basis of clinical and functional outcome (KUJALA score), over 5-year follow-up period. Results: The mean age of the study population was 21.98 years, with a female (63.5%) majority. Among the 52 patients included in the study, 39 patients (75%) had TT-TG <20 mm and 13 patients (25%) had TT-TG = 20–24 mm. We noticed statistically significant improvement in both groups with respect to clinical and functional outcome, with no reported complications. None of the patients had patella alta or high grades of trochlear dysplasia. Conclusion: MPFL reconstruction without concomitant bony procedures can be safely performed in patients with a TT-TG <25 mm, in the absence of patella alta or high-grade trochlear dysplasia. Our modification of isolated MPFL reconstruction has shown excellent long-term results. In addition, our technique uses only a single interference screw, thereby reducing cost of surgery and implant hardware.

Factors Influencing Graft Function following MPFL Reconstruction: A Dynamic Simulation Study

2020 ◽  
Author(s):  
Miho J. Tanaka ◽  
Andrew J. Cosgarea ◽  
Jared M. Forman ◽  
John J. Elias
Keyword(s):  
Dynamic Simulation ◽  
Knee Flexion ◽  
Patellar Instability ◽  
Graft Function ◽  
Lateral Position ◽  
Tibial Tuberosity ◽  
Mpfl Reconstruction ◽  
Patellar Tracking ◽  
Graft Tension ◽  
Patellar Maltracking

AbstractMedial patellofemoral ligament (MPFL) reconstruction is currently the primary surgical procedure for treating recurrent lateral patellar instability. The understanding of graft function has largely been based on studies performed with normal knees. The current study was performed to characterize graft function following MPFL reconstruction, focusing on the influence of pathologic anatomy on graft tension, variations with knee flexion, and the influence on patellar tracking. Knee squatting was simulated with 15 multibody dynamic simulation models representing knees being treated for recurrent lateral patellar instability. Squatting was simulated in a preoperative condition and following MPFL reconstruction with a hamstrings tendon graft set to allow 0.5 quadrants of lateral patellar translation with the knee at 30 degrees of flexion. Linear regressions were performed to relate maximum tension in the graft to parameters of knee anatomy. Repeated measures comparisons evaluated variations in patellar tracking at 5-degree increments of knee flexion. Maximum graft tension was significantly correlated with a parameter characterizing lateral position of the tibial tuberosity (maximum lateral tibial tuberosity to posterior cruciate ligament attachment distance, r 2 = 0.73, p < 0.001). No significant correlations were identified for parameters related to trochlear dysplasia (lateral trochlear inclination) or patella alta (Caton–Deschamps index and patellotrochlear index). Graft tension peaked at low flexion angles and was minimal by 30 degrees of flexion. MPFL reconstruction decreased lateral patellar shift (bisect offset index) compared with preoperative tracking at all flexion angles from 0 to 50 degrees of flexion, except 45 degrees. At 0 degrees, the average bisect offset index decreased from 0.81 for the preoperative condition to 0.71. The results indicate that tension within an MPFL graft increases with the lateral position of the tibial tuberosity. The graft tension peaks at low flexion angles and decreases lateral patellar maltracking. The factors that influence graft function following MPFL reconstruction need to be understood to limit patellar maltracking without overloading the graft or over constraining the patella.

Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability Regardless of Tibial Tubercle–Trochlear Groove Distance and Patellar Height: Outcomes at 1 and 2 Years

2019 ◽  
Vol 47 (6) ◽  
pp. 1331-1337 ◽  
Author(s):  
Brandon J. Erickson ◽  
Joseph Nguyen ◽  
Katelyn Gasik ◽  
Simone Gruber ◽  
Jacqueline Brady ◽  
...  
Keyword(s):  
Patellar Instability ◽  
Medial Patellofemoral Ligament ◽  
Trochlear Dysplasia ◽  
Patellar Height ◽  
Mpfl Reconstruction ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
Outcome Scores ◽  
Recurrent Patellar Instability

Background: It is unclear which patients with recurrent patellar instability require a bony procedure in addition to medial patellofemoral ligament (MPFL) reconstruction. Purpose: To report 1- and 2-year outcomes of patients after isolated MPFL reconstruction performed for patellar instability regardless of patellar height, tibial tubercle–trochlear groove (TT-TG) distance, or trochlear dysplasia. Study Design: Case series; Level of evidence, 4. Methods: All patients with recurrent patellar instability and without significant unloadable chondral defects (Outerbridge grade IV), cartilage defects (especially inferior/lateral patella), previous failed surgery, or pain >50% as their chief complaint were prospectively enrolled beginning March 2014. All patients underwent primary, unilateral, isolated MPFL reconstruction regardless of concomitant bony pathology for treatment of recurrent patellar instability. Information on recurrent subjective instability, dislocations, ability to return to sport (RTS), and outcome scores was recorded at 1 and 2 years. TT-TG distance, patellar height (with the Caton-Deschamps index), and trochlear depth were measured. Results: Ninety patients (77% female; mean ± SD age, 19.4 ± 5.6 years) underwent MPFL reconstruction between March 2014 and August 2017: 72 (80%) reached 1-year follow-up, and 47 (52.2%) reached 2-year follow-up (mean follow-up, 2.2 years). Mean TT-TG distance was 14.7 ± 5.4 mm (range, –2.2 to 26.8 mm); mean patellar height, 1.2 ± 0.11 mm (range, 0.89-1.45 mm); and mean trochlear depth, 1.8 ± 1.4 mm (range, 0.05-6.85 mm). Ninety-six percent of patients at 1 year and 100% at 2 years had no self-reported patellofemoral instability; 1 patient experienced a redislocation at 3.5 years. RTS rates at 1 and 2 years were 90% and 88%, respectively. Mean time to RTS was 8.8 months. All patients had clinically and statistically significant improvement in mean Knee injury and Osteoarthritis Outcome Score–Quality of Life (32.7 to 72.0, P < .001), mean International Knee Documentation Committee subjective form (51.4 to 82.6, P < .001), and mean Kujala score (62.2 to 89.5, P < .001). No difference existed between 1- and 2-year outcome scores (all P > .05). Conclusion: At early follow-up of 1 and 2 years, isolated MPFL reconstruction is an effective treatment for patellar instability and provides significant improvements in outcome scores with a low redislocation/instability rate regardless of bony pathologies, including TT-TG distance, Caton-Deschamps index, and trochlear dysplasia. Future data from this cohort will be used to assess long-term outcomes.

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