A “sandwich” method of reconstruction of the medial patellofemoral ligament using a titanium interference screw for patellar instability in skeletally immature patients

Objectives: Medial patellofemoral ligament (MPFL) reconstruction is the standard of care surgical treatment for recurrent patellar instability. Recurrent patellar instability is common after a first-time dislocation in the skeletally immature population. Adult-type reconstruction techniques are often avoided in skeletally immature patients due to the proximity of the femoral insertion of the MFPL to the distal femoral physis. It is currently unclear how outcomes of MPFL reconstruction in skeletally immature patients compare to those for skeletally mature patients. The objective of this study is to present the outcomes of isolated MPFL reconstruction in skeletally immature patients and compare their findings to a skeletally mature population. Methods: Patients were identified from an institutional patellofemoral registry who underwent isolated MPFL reconstruction from March 2014 to July 2018. Demographic, radiographic, and knee-specific patient-reported outcome measures (PROMs) were collected prior to surgery. Follow-up data collection included knee surveys collected at 1 and 2-years following MPFL reconstruction. Additionally, return to sport rates and episodes of re-dislocations were also collected. Comparisons of demographic and clinical data were made between skeletally immature and mature patients. Sub-analysis was performed on outcomes in skeletally immature patients who underwent MPFL reconstruction where the graft was placed distal to the physis to avoid the growth plate versus those who had standard placement of the graft. Baseline factors were analyzed using independent samples t-tests or chi-square analysis. Longitudinal analysis of knee PROMs was conducted using generalized estimating equation (GEE) modeling. Statistical significance was defined as p-values of 0.05 or less. Results: The study cohort included 107 patients (25 skeletally immature, 82 skeletally mature). Mean age of the study groups was 13.8 years in the immature group (range 11-15) and 21.3 in the mature group (range 14-34). No differences in sex (72% female in both groups) or obesity (0% vs. 8%) was observed between immature and mature patients. Radiographic measures of Caton-Deschamps Index (1.18 in both groups), TT-TG (14.9 vs. 14.8), and Dejour classification (P=0.328) also saw no differences between groups. Longitudinal outcomes in KOOS QoL, IKDC, KOOS PS, and Kujala surveys found no differences between immature versus mature patients over time. However, higher PediFABS was observed in the immature group versus mature at baseline (21.6 vs. 11.9, P<0.001), 1-year (18.1 vs. 11.5, P=0.006), and 2-years (22.4 vs. 11.5, P=0.003). Low incidence of post-operative dislocation and a high return to sport rate was observed in both skeletally immature and mature patients. No statistical differences were observed in all outcomes between immature patients who had standard graft placement and those where the graft was placed distal to the physis. Conclusion: Controversy exists in how best to treat the skeletally immature patient with recurrent lateral patellar instability. Due to the risk of injury to the growth plate, many believe it is best to wait to stabilize these patients until they have stopped growing. However, given the high risk of cartilage injury with each dislocation and the long term sequelae of such injuries in these young knees, the risk of waiting may be high. This study demonstrates similar outcomes and recurrence rates in skeletally immature patients with those seen in the mature population without disturbance or injury to the growth plates. [Figure: see text][Figure: see text]

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Dynamic Medial Patellofemoral Ligament Reconstruction in Patellar Instability: A Surgical Technique

Video Journal of Sports Medicine ◽

10.1177/26350254211023506 ◽

2021 ◽

Vol 1 (6) ◽

pp. 263502542110235

Author(s):

Anna Bartsch ◽

Sebastian Müller ◽

Christian Egloff

Keyword(s):

Surgical Technique ◽

Patellar Instability ◽

Medial Patellofemoral Ligament ◽

Functional Results ◽

Recurrent Dislocation ◽

Interference Screw ◽

Gracilis Muscle ◽

Mpfl Reconstruction ◽

Patella Dislocation ◽

Patella Instability

Background: Patella instability with recurrent dislocations is a result of various pathologies, for example, patella alta, trochlea dysplasia or medial patellofemoral ligament (MPFL) rupture. The recurrent dislocation rate of conservatively treated chronic patellar instability is high; therefore, it is recommended to manage it surgically. This video presents a new operative approach to stabilize the patella in a dynamic MPFL reconstruction, which addresses the most common complications occurring in static reconstructions: malpositioning and overtensioning the graft. Indications: Surgical indications for the new dynamic procedure mirror the indications for static MPFL reconstruction. This is MPFL insufficiency (patella instability in the first 30° of knee flexion), which is most frequently seen in recurrent lateral patella dislocations. Moreover in very rare cases of first patella dislocation with a patellar instability severity score equal or higher than 4. Technique Description: The dynamic MPFL reconstruction consists of 3 steps: First, detaching and mobilizing the gracilis muscle at its anatomical insertion. Second, redirecting the freed gracilis muscle to its new patellar insertion. Third, reinserting the gracilis muscle at the patella. Results: The dynamic MPFL reconstruction has the advantage of lesser risk of overtensioning and malpositioning the graft. The insertion point of the MPFL surrogate is easier to locate, and the patella is dynamically stabilized through reflectory gracilis muscle contraction. Compared with the static reconstruction, only one instead of 3 holes have to be drilled and only 1 interference screw has to be placed, thus shortening the surgery time. From a theoretical biomechanical perspective, the dynamic tensioning is superior to the static procedure. The few accomplished studies published so far by Becher et al and Ostermeier et al show good or better functional results (Kujala, Lysholm, Tegner scores) with the dynamic MPFL reconstruction, yet higher evidence studies need to be performed. Conclusion: Dynamic MPFL reconstruction appears to be a simpler and more effective surgical technique for MPFL reconstruction. Because of its novelty, high evidence studies assessing long-term therapeutical outcomes are still lacking and need to be conducted in order to compare it conclusively with the static procedure.

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

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967121989282 ◽

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.

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Comparing the Tibial Tuberosity–Trochlear Groove Distance Between CT and MRI in Skeletally Immature Patients With and Without Patellar Instability

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120973665 ◽

2021 ◽

Vol 9 (1) ◽

pp. 232596712097366

Author(s):

Zhen-Zhen Dai ◽

Lin Sha ◽

Zi-Ming Zhang ◽

Zhen-Peng Liang ◽

Hao Li ◽

...

Keyword(s):

Patellar Instability ◽

Intraclass Correlation ◽

Mean Difference ◽

Tibial Tubercle ◽

Control Group ◽

Trochlear Groove ◽

Skeletally Immature ◽

Bony Landmarks ◽

The Difference ◽

Ct And Mri

Background: The tibial tubercle–trochlear groove (TT-TG) distance was originally described for computed tomography (CT), but it has been measured on magnetic resonance imaging (MRI) in patients with patellar instability (PI). Whether the TT-TG measured on CT versus MRI can be considered equivalent in skeletally immature children remains unclear. Purpose: To investigate in skeletally immature patients (1) the effects of CT versus MRI imaging modality and cartilage versus bony landmarks on consistency of TT-TG measurement, (2) the difference between CT and MRI measurements of the TT-TG, and (3) the difference in TT-TG between patients with and without PI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We retrospectively identified 24 skeletally immature patients with PI and 24 patients with other knee disorders or injury but without PI. The bony and cartilaginous TT-TG distances on CT and MRI were measured by 2 researchers, and related clinical data were collected. The interrater, interperiod (bony vs cartilaginous), and intermethod (CT vs MRI) reliabilities of TT-TG measurement were assessed with intraclass correlation coefficients. Results: The 48 study patients (19 boys, 29 girls) had a mean age of 11.3 years (range, 7-14 years). TT-TG measurements had excellent interrater reliability and good or excellent interperiod reliability but fair or poor intermethod reliability. TT-TG distance was greater on CT versus MRI (mean difference, 4.07 mm; 95% CI, 2.6-5.5 mm), and cartilaginous distance was greater than bony distance (mean difference, 2.3 mm; 95% CI, 0.79-3.8 mm). The TT-TG measured on CT was found to increase with the femoral width. Patients in the PI group had increased TT-TG distance compared with those in the control group, regardless of landmarks or modality used ( P > .05 for all). Conclusion: For skeletally immature patients, the TT-TG distance could be evaluated on MRI, regardless of whether cartilage or bony landmarks were used. Its value could not be interchanged with CT according to our results; however, further research on this topic is needed.

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Relationship between Anatomical Risk Factors, Articular Cartilage Lesions, and Patient Outcomes Following Medial Patellofemoral Ligament Reconstruction

Cartilage ◽

10.1177/1947603519894728 ◽

2019 ◽

pp. 194760351989472 ◽

Cited By ~ 4

Author(s):

Charles L. Holliday ◽

Laurie A. Hiemstra ◽

Sarah Kerslake ◽

John A. Grant

Keyword(s):

Risk Factors ◽

Odds Ratio ◽

Patellar Instability ◽

Ligament Reconstruction ◽

Medial Patellofemoral Ligament ◽

Trochlear Dysplasia ◽

Cartilage Lesion ◽

Low Grade ◽

Medial Patellofemoral Ligament Reconstruction ◽

Cartilage Lesions

Objective The purpose of this study was (1) to determine which risk factors for patellar instability were associated with the presence of patellofemoral cartilage lesions and (2) to determine how cartilage lesion presence, size, and grade affect postoperative disease-specific quality of life. Design Preoperative, intraoperative, and postoperative demographic, anthropometric (body mass index, Beighton score, hip rotation), radiographic (crossover sign, trochlear bump), cartilage lesion morphology (presence, size, location, grade), and outcomes data (Banff Patella Instability Instrument 2.0 [BPII 2.0]) were prospectively collected from patients undergoing isolated medial patellofemoral ligament reconstruction. For all knees ( n = 264), single and multivariable logistic regression was used to determine if any patellar instability risk factors affected the odds of having a cartilage lesion. In patients with unilateral symptoms ( n = 121), single variable linear regression was used to determine if the presence, size, or ICRS (International Cartilage Regeneration & Joint Preservation Society) grade of cartilage lesions could predict the 12 or 24+ month postoperative BPII 2.0 score. Results A total of 84.5% of knees had patellofemoral cartilage lesions (88.3% involved the distal-medial patella). Trochlear dysplasia (high grade: odds ratio = 15.7, P < 0.001; low grade: odds ratio = 2.9, P = 0.015) was associated with the presence of a cartilage lesion. The presence, size, and grade of cartilage lesions were not associated with 12 or 24+ month postoperative BPII 2.0 scores. Conclusions Trochlear dysplasia was a risk factor for the development of patellofemoral cartilage lesions in this patient population. Cartilage lesions most commonly involve the distal-medial patella. There was no significant relationship between patellofemoral cartilage lesion presence, size, or grade and postoperative BPII 2.0 scores in short-term follow-up.

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SPONTANEOUS CORRECTION OF EXTERNAL TIBIOFEMORAL ROTATION AND TIBIAL TUBEROSITY-TROCHLEAR GROOVE DISTANCE OCCURS AFTER MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION IN FIXED OR OBLIGATORY DISLOCATORS

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967121s00132 ◽

2021 ◽

Vol 9 (7_suppl3) ◽

pp. 2325967121S0013

Author(s):

Alexandra H. Aitchison ◽

Kenneth M. Lin ◽

Daniel W. Green

Keyword(s):

Patellar Instability ◽

Ligament Reconstruction ◽

Medial Patellofemoral Ligament ◽

Extensor Mechanism ◽

Tibial Tubercle ◽

Trochlear Groove ◽

Medial Patellofemoral Ligament Reconstruction ◽

Force Vector ◽

Tibiofemoral Rotation ◽

The Mean

Background: Tibial tubercle to trochlear groove distance (TT-TG) and external tibiofemoral rotation (TFR) through the knee joint have been identified potential contributing factors to patellar instability. In patients with a fixed or obligatory lateral patella dislocation (FOD), the normal force vector of the extensor mechanism is altered, so instead of a direct axial pull to cause extension, it exerts a lateralizing and external rotatory force on the tibia via the tibial tubercle. Hypothesis/Purpose: The purpose of this study is to investigate postoperative changes in TT-TG and TFR after medial patellofemoral ligament reconstruction (MPFLR) in two clinical cohorts: standard traumatic patellar instability (SPI) patients and FOD patients. We hypothesized that by surgically relocating the patella in the trochlea, and re-establishing medial sided soft tissue tension, the increased medializing force vector on the patella may exert enough force to alter resting rotation of the tibia in relation to the femur in the FOD group. Methods: A retrospective study was performed from April 2009 to February 2019. FOD and SPI patients under 18 years with available magnetic resonance imaging (MRI) of the knee before and after MPFLR were eligible. All FOD patients in the time frame were analyzed and SPI patients were randomly selected. Exclusion criteria were outside institution MRI, concomitant alignment procedures done at the time of MPFLR, and prior MPFLR or tibial tubercle osteotomy. TT-TG and TFR (using the posterior femoral and tibial condylar lines) were measured blindly on initial axial MRI. Statistical analysis using a paired sample t-test was performed with significance set at p<0.05. Results: A total of 30 patients were included, 14 in the FOD group and 16 in the SPI group. The mean age at time of surgery was 13.9 years (range 10-17 years), 53% of the cohort was female, and the mean time from surgery to follow-up MRI was 2.0 years. Demographics by group are shown in Table 1. TT-TG and TFR were not significantly different preoperatively versus postoperatively in the SPI group (Table 2). In the FOD group, both TT-TG (17.7 vs 13.7, P=.019) and TFR (8.6 vs 3.1, P=.025) decreased significantly on postoperative MRI. Conclusion: The postoperative decrease in TT-TG and TFR in the FOD group suggests that MPFLR in fixed or obligatory dislocators can improve the external rotation deformity through the level of the joint, and thus may help normalize the forces acting through the extensor mechanism. Tables/ Figures [Table: see text][Table: see text]

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Anatomic and Biomechanical Properties of Flat Medial Patellofemoral Ligament Reconstruction Using an Adductor Magnus Tendon Graft: A Human Cadaveric Study

The American Journal of Sports Medicine ◽

10.1177/03635465211009540 ◽

2021 ◽

pp. 036354652110095

Author(s):

Danko Dan Milinkovic ◽

Christian Fink ◽

Christoph Kittl ◽

Petri Silanpää ◽

Elmar Herbst ◽

...

Keyword(s):

Medial Patellofemoral Ligament ◽

Biomechanical Properties ◽

Mpfl Reconstruction ◽

Maximum Elongation ◽

Skeletally Immature ◽

Femoral Insertion ◽

Adductor Tubercle ◽

Adductor Magnus ◽

Load To Failure ◽

The Mean

Background: In contrast to the majority of existing techniques for reconstruction of the medial patellofemoral ligament (MPFL), the technique described in this article uses the adductor magnus muscle tendon to gain a flat, broad graft, leaving its distal femoral insertion intact, and does not require drilling within or near the femoral physis. It also allows for soft tissue patellar fixation and could facilitate anatomic MPFL reconstruction in skeletally immature patients. Purpose: To evaluate the anatomic and structural properties of the native MPFL and the adductor tendon (AT), followed by biomechanical evaluation of the proposed reconstruction. Study Design: Descriptive laboratory study. Methods: The morphological and topographical features of the AT and MPFL were evaluated in 12 fresh-frozen cadaveric knees. The distance between the distal insertion of the AT on the adductor tubercle and the adductor hiatus, as well as the desired length of the graft, was measured to evaluate this graft’s application potential. Load-to-failure tests were performed to determine the biomechanical properties of the proposed reconstruction construct. The construct was placed in a uniaxial testing machine and cyclically loaded 500 times between 5 and 50 N, followed by load to failure, to measure the maximum elongation, stiffness, and maximum load. Results: The mean ± SD length of the AT was 12.6 ± 1.5 cm, and the mean distance between the insertion on the adductor tubercle and adductor hiatus was 10.8 ± 1.3 cm, exceeding the mean desired length of the graft (7.5 ± 0.5 cm) by 3.3 ± 0.7 cm. The distal insertion of the AT was slightly proximal and posterior to the insertion of the MPFL. The maximum elongation after cyclical loading was 1.9 ± 0.4 mm. Ultimately, the mean stiffness and load to failure were 26.2 ± 7.6 N/mm and 169.7 ± 19.2 N, respectively. The AT graft failed at patellar fixation in 2 of the initially tested specimens and at the femoral insertion in the remaining 10. Conclusion: The described reconstruction using the AT has potential for MPFL reconstruction. The AT graft presents a graft of significant volume, beneficial anatomic topography, and adequate tensile properties in comparison with the native MPFL following the data from previously published studies. Clinical Relevance: Given its advantageous anatomic relationship as an application that avoids femoral drilling and osseous patellar fixation, the AT may be considered a graft for MPFL reconstruction in skeletally immature patients.

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