Primary Medial Patellofemoral Ligament Reconstruction Research Articles

Incidence of Early Adverse Events Following Medial Patellofemoral Ligament Reconstruction.

The current literature lacks data regarding perioperative complications after medial patellofemoral ligament reconstruction (MPFLr). The objective of this study was to identify the incidence and predictors of adverse events in the first 90 days after MPFLr. Patients undergoing primary MPFLr between January 1, 2010, and December 31, 2019, were included. Predictors of readmission for any reason were identified using a multivariable logistic regression analysis. A total of 140 MPFLrs were included in the final analysis. Of these, 17 patients (12.1%) were admitted in the first 90 days after MPFLr. The most common reason for readmission was pain (7/140, 5%), followed by cellulitis (5/140, 3.5%). The only major complication was pulmonary embolism experienced by one patient (1/140, 0.7%). Univariate logistic regression analysis demonstrated that patients who ever smoked were 4.5 times (p = 0.005) more likely to be readmitted in the first 90 days. Although additional soft-tissue procedures increased the readmission rated by 21% (p = 0.810) and additional chondral procedure increased by 35% (p = 0.568), the multivariable analysis did not reveal a significant difference. Surgeons can use this information to counsel patients on what to expect following MPFLr.

Poster 289: Impact of Graft Selection on Clinical Outcomes following Isolated MPFL Reconstruction in Adolescent and Young Adult Athletes

Objectives: Patellofemoral instability (PFI) commonly requires surgical intervention in adolescent and young adult athletes. However, the clinical impact of graft selection, which may vary amongst surgeons, has not been well studied. The purpose of this study was therefore to compare clinical outcomes, including recurrent instability reoperations and complications, of medial patellofemoral ligament reconstruction (MPFLR), based on graft type. Methods: Electronic medical records of patients who underwent primary MPFLR surgery for PFI over a 10-year period between 2010 and 2019 at a single center were retrospectively reviewed. Collected data included demographic, clinical, and radiologic parameters of instability and post-operative clinical outcomes. Exclusion criteria included concomitant extensor realignment procedures (tibial tubercle osteotomy, patellar tendon transfer procedures) and factors that would alter routine surgical indications or technical approaches, such as fixed or syndromic PFI, osteochondral shear fractures undergoing fixation or >1 cm in diameter, and prior ipsilateral knee surgery. Results: One-hundred and one patients (average age 15.2 years, 63% female), underwent primary isolated MPFLR with an average follow up time of 2.87 years. There were no significant differences in demographic and radiographic parameters between autograft and allograft, other than more semitendinosus grafts, increased number of pre-op dislocation events, and higher sulcus angle in autograft (Table 1). The autograft group had a higher rate of recurrent instability (41% vs 14%, p = 0.01) but no significant difference in return to sport, complications, and reoperations (Table 2). Reoperations for recurrent instability were performed in 9% of all patients (Table 3). Subgroup analysis of allograft tendon type demonstrated more dislocations and recurrent instability in gracilis than semitendinosus, though these differences were not statistically significant, and there was no difference in recurrent instability surgery or complications (Table 4). Conclusions: In adolescent and young adult athletes undergoing isolated primary MPFLR for PFI, allograft may be associated with decreased rates of recurrent instability compared to autograft. While trends towards higher recurrent instability were detected with gracilis allograft, compared to semitendinosus allograft, the precise role of allograft tendon type would benefit from future studies with larger sample size to better elucidate its impact on clinical outcomes.

Systematic Review: Pedicled Strip of Quadriceps Tendon Graft for Primary Medial Patellofemoral Ligament Reconstruction in Recurrent Patellofemoral Instability

Systematic Review: Pedicled Strip of Quadriceps Tendon Graft for Primary Medial Patellofemoral Ligament Reconstruction in Recurrent Patellofemoral Instability

Home ownership, full-time employment, and other markers of higher socioeconomic status are predictive of shorter time to initial evaluation, shorter time to surgery, and superior postoperative outcomes among lateral patellar instability patients undergoing medial patellofemoral ligament reconstruction

BackgroundThe purpose of this study was to identify socioeconomic predictors of time to initial evaluation, time to surgery, and postoperative outcomes among lateral patellar instability patients undergoing medial patellofemoral ligament reconstruction (MPFLR).MethodsWe conducted a retrospective review of patients at our institution who underwent primary MPFLR with allograft from 2011 to 2019 and had minimum 12-month follow-up. Patients were administered an email survey in January 2022 to assess symptom history, socioeconomic status, and postoperative outcomes including VAS satisfaction and Kujala score. Predictors of time to initial evaluation, time to surgery, and postoperative outcomes were identified using multivariable linear and logistic regression with stepwise selection.ResultsSeventy patients were included in the cohort (mean age 24.8 years, 72.9% female, mean follow-up time 45.7 months). Mean time to evaluation was 6.4 months (range 0–221) and mean time to surgery was 73.6 months (range 0–444). Having a general health check-up in the year prior to surgery was predictive of shorter time to initial evaluation (β = − 100.5 [− 174.5, − 26.5], p = 0.008). Home ownership was predictive of shorter time to surgery (β = − 56.5 [− 104.7, 8.3], p = 0.02). Full-time employment was predictive of higher VAS satisfaction (β = 14.1 [4.3, 23.9], p = 0.006) and higher Kujala score (β = 8.7 [0.9, 16.5], p = 0.03).ConclusionMarkers of higher socioeconomic status including having a general check-up in the year prior to surgery, home ownership, and full-time employment were predictive of shorter time to initial evaluation, shorter time to surgery, and superior postoperative outcomes.Level of evidence: IV, retrospective case series.

Poster 255: Socioeconomic Predictors of Time to Initial Evaluation, Time to Surgery, and Postoperative Outcomes among Medial Patellofemoral Ligament Reconstruction Patients

Objectives: Operative management of patellar instability with medial patellofemoral ligament reconstruction (MPFLR) has been associated with good results, but socioeconomic disparities may be an obstacle to patients receiving timely care and achieving satisfactory outcomes. The purpose of this study was to identify socioeconomic predictors of time to initial evaluation, time to surgery, and postoperative outcomes among lateral instability patients undergoing MPFLR. Methods: We conducted a retrospective review of patients at our institution who underwent primary MPFLR with allograft from 2011 to 2019. Patients were administered an email survey to assess symptom history, socioeconomic variables (ex. language, race, ethnicity, marital status, household size), and postoperative outcomes including Visual Analog Scale (VAS) pain, Kujala score, MPFL-Return to Sport After Injury (MPFL-RSI) score, and return to work and sport. Predictors of time to initial evaluation, time to surgery, concomitant procedures, and postoperative outcomes were identified using multivariable linear and logistic regression with stepwise selection. P-values less than 0.05 were considered significant. Results: Seventy patients were included in the cohort (mean age 24.8 years, 72.9% female, mean follow- up time 45.7 months). Mean time to evaluation was 6.4 months (range 0-221) and mean time to surgery was 73.6 months (range 0-444). Home ownership was predictive of reduced time to surgery (β: -56.5 [- 104.7 to -8.3]; p = 0.02). Non-white race was predictive of increased odds of undergoing a concomitant procedure (OR: 12.4 [1.8 to 83.4]; p = 0.01). Full-time employment was predictive of higher satisfaction (β: 14.1 [4.3 to 23.9]; p = 0.006) and higher Kujala score (β: 8.7 [0.9 to 16.5]; p = 0.03). Conclusions: Certain markers of higher socioeconomic status, including home ownership and full-time employment, were predictive of higher satisfaction and knee function following MPFLR for patellar instability. Non-white race was associated with higher risk of concomitant procedures. Identifying modifiable socioeconomic risk factors for delayed presentation and poorer surgical outcomes may allow surgeons to prioritize earlier intervention among the most vulnerable segments of their patient population.

Patients who undergo bilateral medial patellofemoral ligament reconstruction return to sport at a similar rate as those that undergo unilateral reconstruction.

Lateral patellar instability is a debilitating condition not only to athletes, but also to a wide range of highly active individuals. Many of these patients experience symptoms bilaterally, though it is unknown how these patients fair with return to sports following a second medial patellofemoral ligament reconstruction (MPFLR). The purpose of this study is to evaluate the rate of return to sport following bilateral MPFLR compared to a unilateral comparison group. Patients who underwent primary MPFLR with minimum 2-year follow-up were identified from 2014 to 2020 at an academic center. Those who underwent primary MPFLR of bilateral knees were identified. Pre-injury sport participation and Tegner score, Kujala score, Visual Analog Score (VAS) for pain, satisfaction, and MPFL-Return to Sport after Injury (MPFL-RSI) scale were collected. Bilateral and unilateral MPFLRs were matched in a 1:2 ratio based on age, sex, body mass index, and concomitant tibial tubercle osteotomy (TTO). A sub-analysis was performed regarding concomitant TTO. The final cohort consisted of 63 patients, including 21 patients who underwent bilateral MPFLR, matched to 42 unilateral patients at mean follow-up of 47 ± 27months. Patients who underwent bilateral MPFLR returned to sport at a rate of 62% at a mean of 6.0 ± 2.3months, compared to a unilateral rate of 72% at 8.1 ± 4.2months (n.s.). The rate of return to pre-injury level was 43% among bilateral patients and 38% in the unilateral cohort. There were no significant differences in VAS pain, Kujala, current Tegner, satisfaction, and MPFL-RSI scores between cohorts. Approximately half of those (47%) who failed to return to sport cited psychological factors and had significantly lower MPFL-RSI scores (36.6 vs 74.2, p = 0.001). Patients who underwent bilateral MPFLR returned to sports at a similar rate and level compared to a unilateral comparison group. MPFL-RSI was found to be significantly associated with return to sport. III.

Podium Presentation Title: Outcomes for Medial Patellofemoral Ligament Reconstruction with Concomitant Tibial Tubercle Osteotomy for Failed Patellar Stabilization versus Primary Medial Patellofemoral Ligament Reconstruction with Concomitant Tibial Tubercle Osteotomy

Podium Presentation Title: Outcomes for Medial Patellofemoral Ligament Reconstruction with Concomitant Tibial Tubercle Osteotomy for Failed Patellar Stabilization versus Primary Medial Patellofemoral Ligament Reconstruction with Concomitant Tibial Tubercle Osteotomy

Preoperative Patella Alta on Caton-Deschamps Index Is a Predictor of Outcome Following Isolated Medial Patellofemoral Ligament Reconstruction

The purpose of this study was to determine whether a preoperative Caton-Deschamps index (CDI) ≥ 1.30, as measured by magnetic resonance imaging, is associated with rates of postoperative instability, revision knee surgery, and patient-reported outcomes in patients undergoing isolated medial patellofemoral ligament (MPFL) reconstruction. Patients who underwent primary medial patellofemoral ligament reconstruction (MPFLR) between 2015 and 2019 at a single institution were assessed. Only those with at least 2 year follow up were included. Patients who had undergone a previous ipsilateral knee surgery, concomitant tibial tubercle osteotomy and/or ligamentous repair/reconstruction at the time of MPFL reconstruction were excluded from the study. CDIs were evaluated by three investigators based on magnetic resonance imaging measurement. Patients with a CDI ≥ 1.30 were included in the patella alta group, while those with a CDI between 0.70 and 1.29 served as controls. A retrospective review of clinical notes was used to evaluate the number of postoperative instability episodes and revisions. Functional outcomes were measured by the International Knee Documentation Committee (IKDC) and 12-Item Short Form Health Survey (SF-12) physical and mental scores. Overall, 49 patients (50 knees, 29 males, 59.2%) underwent isolated MPFLR. Nineteen (38.8%) patients had a CDI ≥ 1.30 (mean: 1.41, range: 1.30-1.66). The patella alta group was significantly more likely to experience a postoperative instability episode (36.8% vs 10.0%; P= .023) and was more likely to return to the operating room for any reason (26.3% vs 3.0%; P= .022) compared to those with normal patellar height. Despite this, the patella alta group had significantly greater postoperative IKDC (86.5 vs 72.4; P= .035) and SF-12 physical (54.2 vs 46.5; P= .006) scores. Pearson's correlation showed a significant association between CDI and postoperative IKDC (R 2= 0.157; P= .022) and SF-12P (R 2= .246; P= .002) scores. There was no difference in postoperative Lysholm (87.9 vs 85.1; P= .531). and SF-12M (48.9 vs 52.5; P= .425) scores between the groups. Patients with preoperative patella alta, as measured by CDI had higher rates of postoperative instability and return to the OR with isolated MPFL reconstruction for patellar instability. Despite this, higher preoperative CDI was associated with greater postoperative IKDC scores and SF-12 physical scores in these patients. Retrospective cohort study, Level IV.

Predictors of Graft Failure After Primary Medial Patellofemoral Ligament Reconstruction.

The tibiofemoral rotation angle has been found to be higher in patients with recurrent patellar dislocations (RPDs) than in healthy people; however, little is known about the clinical significance of this finding. To determine whether an increased tibiofemoral rotation angle is associated with graft failure after primary medial patellofemoral ligament reconstruction (MPFL-R) and to investigate the role of the tibiofemoral rotation angle in predicting MPFL-R failure in patients with RPDs. Case-control study; Level of evidence, 3. We retrospectively analyzed the records of 632 consecutive patients with clinically diagnosed RPDs from 2011 to 2018. Postoperative stress radiography of the patellofemoral joint was performed to identify whether the graft failed. After a review, 33 patients who showed MPFL-R failure were allocated to the failure group. They were matched 1:2 to 66 participants who underwent successful MPFL-R (control group). The cutoff value and area under the curve (AUC) of the tibiofemoral rotation angle for predicting graft failure after primary MPFL-R were determined, and the risk factors for MPFL-R failure were assessed by multivariate logistic regression analysis. The tibiofemoral rotation angle was significantly higher in the failure group than in the control group (16.4° ± 5.6° vs 6.4° ± 4.5°, respectively; P < .001). The cutoff value of the tibiofemoral rotation angle for predicting graft failure was 12.3° (sensitivity, 81.8%; specificity, 89.4%; AUC, 0.920). Overall, 3 risk factors for MPFL-R failure were determined: excessive tibiofemoral rotation (≥12.3°) (odds ratio [OR], 13.159 [95% CI, 2.469-70.139]; P = .003), a preoperative high-grade J-sign (OR, 7.674 [95% CI, 1.232-47.809]; P = .029), and a femoral tunnel malposition (OR, 6.976 [95% CI, 1.077-45.187]; P = .042). In this study, excessive tibiofemoral rotation, a preoperative high-grade J-sign, and a femoral tunnel malposition were identified as risk factors for graft failure after primary MPFL-R in patients with RPDs. More importantly, excessive tibiofemoral rotation ( ≥ 12.3°) may predict the failure of primary MPFL-R, which can help surgeons easily identify high-risk patients of MPFL-R failure before surgery.

Poster 232: Performing a Concomitant Tibial Tubercle Osteotomy During Primary Medial Patellofemoral Ligament Reconstruction Does Not Lead to Increased Post-Operative Complication Rates

Objectives:Tibial tubercle osteotomy is utilized to unload cartilage defects and/or to correct malalignment in the setting of patellofemoral instability and/or chondrosis. Controversy remains regarding the indications for TTO as an adjunct to soft tissue stabilization for patella instability. Our purpose was to evaluate safety and efficacy of MPFLR with or without concomitant tibial tubercle osteotomy (TTO). Our hypothesis was that adding TTO to MPFLR would lead to lower revision instability surgical rates but higher rates of overall re-operation, complication, and cost.Methods:We queried the MarketScan database in order to identify patients who underwent primary MPFLR from 2007-2015. Patients were stratified into cohorts based on concomitant TTO performed on the same day as index MPFLR. To minimize the effect of potential confounding on the direct comparison of patients undergoing the two procedures, a propensity-score match (PSM) was utilized. A greedy nearest-neighbor algorithm was employed to match patient cohorts with a 7:1 MPFLR to MPFLR + TTO ratio. Reoperations, complications, and costs were followed for two years post-index procedure. Patients without laterality codes were excluded. Results were analyzed statistically.Results:This study identified 968 patients who underwent primary MPFLR. Patients were stratified into two groups: 1) MPFLR only or 2) MPFLR + TTO. After matching the cohorts, mean age, sex distribution, and rates of baseline diabetes, hyperlipidemia, hypertension, tobacco use, and obesity were similar. Patients in the two cohorts experienced similar rates of postoperative complications (MPFLR + TTO: 9.9%, MPFLR: 8.7%, p= 0.6694). Rates of dislocation (MPFLR + TTO: 5.8%, MPFLR: 4.3%, p = 0.4434), stiffness (MPFLR + TTO: 0.8%, MPFLR: 2.5%, p = 0.2538), infection (MPFLR + TTO: 0.8%, MPFLR: 0.6%, p = 0.7559), and wound complication (MPFLR + TTO: 0.8% vs MPFLR: 0.8%, p = 1.000) were similarly low. Performing a concomitant TTO decreased revision surgery for instability (revision MPFLR) rates (6.6% vs 11.1%, p = 0.1327); however, this difference was not statistically significant. Hardware removal (MPFLR + TTO: 9.9%, MPFLR: 1.9%, p < 0.0001) was higher in the MPFLR + TTO cohort. Patients who underwent a concomitant TTO were associated with higher payments through 2 years of index surgery when compared to MPFLR only patients ($25,740 vs $17,727, p < 0.0001).Conclusions:Concomitant TTO at the time of MPFLR does not lead to increased post-operative complications. The addition of TTO to MPFLR reduced revision surgical rates for instability from 11.1 to 6.6% but this difference was not statistically significant. Combination TTO/MPFLR led to higher payments through 2 years. Further research is needed to refine the indications for TTO as a adjunct procedure to MPFLR and its impact on long-term stability and failure rates.Table 1.Demographics and Baseline ComorbiditiesTable 2.Postoperative Complications - within 90 daysTable 3.Quality OutcomesTable 4.Non-obese vs Obese Subgroup AnalysisTable 6.Age <30 vs Age >30 Subgroup AnalysisTable 7.Non-smoker versus Smoker Subgroup Analysis

The Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient-Acceptable Symptomatic State after Medial Patellofemoral Ligament Reconstruction

PurposeTo define the minimal clinically important difference (MCID), substantial clinical benefit (SCB) and patient-acceptable symptomatic state (PASS) for patient-reported outcome measures (PROMs) after medial patellofemoral ligament reconstruction (MPFLR) and to investigate the role of preoperative, demographic, and intraoperative variables for predicting achievement of these thresholds.MethodsThis retrospective cohort study used a prospectively maintained database of patients undergoing primary MPFLR between August 2015 and December 2019. PROMs included the International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS joint replacement (JR), and Kujala. Anchor-based and distribution-based methods were used to calculate the MCID, SCB, and PASS. Regression analyses were performed to identify prognosticators for achievement of clinically significant thresholds.Results139 patients met inclusion criteria (mean age: 21.7± 8.2 years). At 6 months, the MCID values were 8.3 (KOOS-Pain) and 8.5/13.5 (Kujala); SCB values were 1.4 (KOOS-Pain) and 43.7 (KOOS-QOL); and PASS values were 64.9 (IKDC), 83.3 (KOOS-Symptom), 76.8 (KOOS-Pain), 91.2 (KOOS-ADL), 47.5 (KOOS-Sport), 40.6 (KOOS-QOL), and 78.1 (KOOS-JR). At 1 year, the MCID values were 4.2 (KOOS-Pain), 7.2 (KOOS-ADL), 12.4 (KOOS-QOL) and 25.2 (KOOS-JR); SCB were 23.6 (IKDC), 4.2 (KOOS-Symptom), 19.7 (KOOS-Pain), 6.5 (KOOS-ADL), 55.0 (KOOS-Sport), 6.3 (KOOS-QOL), and 19.6/25.2 (KOOS-JR); and PASS were 65.5 (IKDC), 80.4 (KOOS-Symptom), 84.7 (KOOS-Pain), 99.3 (KOOS-ADL), 57.5 (KOOS-Sport), 53.1 (KOOS-QOL), and 76.3 (KOOS-JR). In regression analysis, greater age, body mass index, and preoperative PROMs were negative prognosticators for achieving clinically significant thresholds. Conversely, male gender increased the likelihood of achieving PASS for Kujala at 6 months and KOOS-ADL at 1 year.ConclusionsThis study established thresholds for the MCID, SCB, and PASS at 6 months and 1 year after MPFLR, providing physicians an evidence-based method to advise patients and assess outcomes with this surgery. Older patients and those with higher preoperative outcome scores are less likely to report improvement and satisfaction with MPFLR, while male patients are more likely to report some satisfaction.Level of EvidenceLevel III, retrospective cohort study (diagnosis).

Tape Augmentation Does Not Affect Mid-Term Outcomes of Medial Patellofemoral Ligament Reconstruction in Skeletally Mature Adolescent Patients

PurposeTo evaluate mid-term outcomes after medial patellofemoral ligament (MPFL) reconstruction with and without tape augmentation in the skeletally mature adolescent population.MethodsAll patients under age 18 with recurrent patellar instability treated with surgery at a single institution by a single surgeon from January 2013 through June 2017 were identified by current procedural terminology codes. Inclusion criteria were (1) primary MPFL reconstruction, (2) minimum 3 years’ follow-up, (3) skeletal maturity. Exclusion criteria were (1) bilateral MPFL reconstruction using different techniques on each knee, (2) prior surgery for patellar instability. Chart and imaging review was completed. Patients were contacted to complete a questionnaire, which included the International Knee Documentation Committee (IKDC) form.ResultsFifty-one of 92 eligible patients completed questionnaires. Two patients were excluded. Twenty patients underwent 23 non-augmented MPFL reconstructions; 29 patients underwent 33 augmented MPFL reconstructions. Group demographics were similar. At 4.9 ± 1.2 years follow-up, mean IKDC scores were 77.4 and 79.4 in the nonaugmentation and augmentation groups, respectively. Significantly fewer patients in the augmentation group experienced further injury to their ipsilateral knee compared to the non-augmentation group (6% vs 30%, P = .019). Fewer knees in the augmentation group developed recurrent subjective instability or dislocation after initial surgery requiring surgical correction compared to knees in the nonaugmentation group, although this difference was not significant (6% vs 17%, P = 0.181). Overall patient-reported outcomes were similar between the 2 groups.ConclusionsThere were no significant differences in patient-reported outcomes after MPFL reconstruction with or without tape augmentation. Tape augmentation significantly decreased the risk of subsequent ipsilateral knee injuries, although it did not show a significant difference in recurrent dislocations.Level of EvidenceIV, therapeutic case series.

Derotational distal femoral osteotomy yields satisfactory clinical outcomes in pathological femoral rotation with failed medial patellofemoral ligament reconstruction.

The purpose of this study was to evaluate the clinical outcomes of de-rotational distal femoral osteotomy (DDFO) in patients who underwent primary medial patellofemoral ligament reconstruction (MPFLR) failure with increased femoral anteversion along with high-grade J sign. Between 2011 and 2019, 14 patients underwent DDFO revision surgery due to failed MPFLR. The pre- and postoperative J sign grade, Caton-Deschamps index (CDI), tibial tuberosity-trochlear groove (TT-TG) distance, femoral anteversion angle (FAA), patellar lateral tilt angle (PLTA), MPFL graft laxity, and patient-reported outcomes (Kujala, Lysholm, Tegner, and International Knee Documentation Committee (IKDC) subjective scores) were collected. The anterior-posterior and proximal-distal distances between the actual point and the Schöttle point were also calculated. Fourteen patients underwent MPFLR revision by DDFO combined with MPFLR. The mean PLTA improved from 40.7° ± 11.9° to 20.5° ± 8.7° (P < 0.001). The mean FAA significantly decreased from 42.7° ± 12.0° to 14.1° ± 5.2° (P < 0.001). The mean patellar laxity index (PLI) decreased from 82.4% preoperatively to 15.1% postoperatively (P < 0.001). None of these patients experienced subluxation or re-dislocation during follow-up of 29.7 ± 5.0months after revision surgery. Meanwhile, the Tegner score at the last follow-up ranged from 3 to 6, with a median of 5. The Kujala, Lysholm, and IKDC subjective scores showed significant improvements, from a mean of 51.0 ± 6.8 preoperatively to 75.4 ± 5.1 postoperatively (P < 0.001), 49.2 ± 7.9 to 75.2 ± 7.2 (P < 0.001), and 42.9 ± 6.2 to 76.8 ± 6.0 (P < 0.001), respectively. The proportion of patients with a high-grade J sign was significantly lower postoperatively than preoperatively (100% vs. 14%). Four out of 14 patients (29%) showed femoral tunnel mal-positioning. MPFLR revision by DDFO combined with MPFLR achieved favorable clinical outcomes in patients with increased femoral anteversion along with high-grade J sign. IV.

Strong Agreement Between Magnetic Resonance Imaging and Radiographs for Caton–Deschamps Index in Patients With Patellofemoral Instability

PurposeTo compare the measurements of the Caton–Deschamps index on preoperative magnetic resonance imaging and radiographs of patients undergoing operative management of patellar instability.MethodsPatients who underwent primary medial patellofemoral ligament reconstruction and/or tibial tubercle osteotomy between January 2015 and November 2019 were assessed. Caton–Deschamps indices were measured by 3 independent reviewers on both radiographs and magnetic resonance imaging. Intra- and interclass correlation coefficients and a Bland–Altman analysis were calculated to assess inter-rater reliability and measurement agreement between radiographic and magnetic resonance imaging.ResultsSeventy-two patients (73 knees) were identified. The average Caton–Deschamps index was 1.23 ± 0.18 on radiograph and 1.26 ± 0.18 on magnetic resonance imaging. Strong inter-rater reliability was observed between reviewers for both radiographic and magnetic resonance imaging Caton–Deschamps indices (intraclass correlation coefficients 0.700 and 0.715, respectively). Pooled observer measurements revealed a moderate agreement between radiographic and magnetic resonance imaging for patella to tibia distance, weak agreement for patellar articular cartilage distance, and strong agreement for the Caton–Deschamps index (intraclass correlation coefficients 0.687, 0.485, and 0.749, respectively). Bland–Altman analysis demonstrated a mean difference in Caton–Deschamps index of –0.03 ± 0.15 (95% limits of agreement: –0.29 to 0.23) between radiographic and magnetic resonance imaging, meaning that Caton–Deschamps indices were on average 0.03 lower on radiographic than on magnetic resonance imaging.ConclusionsThe Caton–Deschamps index has strong agreement between radiographic and magnetic resonance imaging in patients undergoing patellar stabilization surgery. Either modality can be reliably used to preoperatively assess patellar height.Level of EvidenceLevel IV, diagnostic case series.

Primary Medial Patellofemoral Ligament Reconstruction in Military Servicemembers: Can We Reliably Restore Preinjury Function and Stability?

Background:Medial patellofemoral ligament (MPFL) reconstruction for patellar instability is a commonly performed procedure with a reported high rate of return to preinjury activity. However, no previous study has assessed the functional outcomes of military servicemembers undergoing MPFL reconstruction.Hypothesis:Primary MPFL reconstruction confers patellar stability, but with limited return to preinjury function and ability to maintain unrestricted military active duty status.Study Design:Case series; Level of evidence, 4.Methods:Using the Management Analysis and Reporting Tool database, we conducted a retrospective review of active duty servicemembers throughout the US Department of Defense Health System who underwent primary MPFL reconstruction between 2012 and 2015. Demographic variables were recorded as well as ability to return to impact activities—defined as running, jumping, rucking with a load >40 pounds (18 kg), and returning to airborne operations—and to remain on active duty status. The rates of recurrent instability and the need for subsequent surgeries were identified and assessed for statistical significance using uni- and multivariate analyses. Patients were evaluated for a minimum of 2 years postoperatively.Results:Of the 213 patients who underwent primary MPFL reconstruction, including 34 with concomitant tibial tubercle osteotomy, 19 (8.9%) patients developed recurrent instability. The presence of bilateral patellar instability was associated with higher recurrence rate. Patients with bilateral instability comprised 47.3% of those with recurrence but only 24.9% of patients without recurrence (P = .019). Impact activity restrictions were present in 57.6% of patients (n = 121), with 86 patients (52.1%) undergoing medical separation from the military. Patients who were prescribed activity restriction before surgery were significantly more likely to have postoperative activity restrictions (64.5%; P = .019), and junior enlisted servicemembers were more likely to be medically separated from service postoperatively than higher ranking senior enlisted members or officers.Conclusion:Only 42.4% of US military servicemembers undergoing primary MPFL reconstruction were able to return to unrestricted impact activity after surgery. Bilateral instability negatively affected return to impact activities. Military servicemembers, particularly junior enlisted members, should be counseled on this poor prognosis for a full return to unrestricted activity postoperatively.

Small, Short, Oblique Patellar Tunnels for Patellar Fixation Do Not Increase Fracture Risk or Complications in MPFL Reconstruction: A Retrospective Cohort Study.

Background:Large (4.5 mm) and/or transpatellar bone tunnels have been associated with patellar fracture after medial patellofemoral ligament (MPFL) reconstruction. To avoid this outcome, many surgeons now employ suture anchors to affix the MPFL graft to the patella.Purpose:To evaluate the risk of patellar fracture and other outcomes associated with smaller (3.2-mm), short, oblique patellar tunnels as compared with suture anchor fixation in MPFL reconstruction.Study Design:Cohort study; Level of evidence, 3.Methods:A single institution’s electronic medical record was queried for all patients undergoing MPFL reconstruction between March 2010 and December 2018. A chart review of operative reports was utilized to identify those who had undergone MPFL reconstruction. Patients undergoing revision MPFL reconstruction or reconstruction with fully transpatellar bone tunnels were excluded. The incidence of patellar fracture and outcomes were evaluated from chart review. The mean duration of follow-up was >2 years.Results:A total of 384 knees in 352 patients undergoing primary MPFL reconstruction were identified. Small (3.2-mm), short, oblique tunnels were used for patellar fixation in 215 cases, and suture anchors were utilized in 169 cases. The small, oblique tunnels and suture anchor techniques both resulted in a low incidence of patellar fracture, with rates of 0.47% and 0%, respectively. The use of suture anchors was associated with an increased risk of subluxation or dislocation compared with small, oblique tunnels (odds ratio, 3.98; P = .028). No significant difference was found in the need for revision MPFL reconstruction surgery with suture anchors (odds ratio, 1.925; P = .66).Conclusion:The use of small, oblique tunnels with hamstring autograft is a safe means of patellar fixation in MPFL reconstruction. The use of small, oblique tunnels for patellar fixation versus 2 suture anchors can result in material cost savings with no significantly increased risk for fracture as well as an overall reduction in complication rates.

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

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.

Establishing the Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient Acceptable Symptomatic State following Primary Medial Patellofemoral Ligament Reconstruction

Objectives:Medial patellofemoral ligament (MPFL) reconstruction is an effective surgical procedure for patients with recurrent lateral dislocations. Outcome measurements can identify the success of a surgical procedure but are shifting away from absolute values or deltas of patient-reported outcomes (PROs) towards the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS), representing the smallest clinical improvement that patients perceive as important, the threshold at which patients notice a considerable improvement, and patient satisfaction with their outcome, respectively. To our knowledge no prior study has defined these thresholds in MPFL reconstruction patients.Methods:An institutional database was reviewed for patients who underwent primary MPFL reconstruction between August 2015 to February 2018 with a minimum 6-month follow-up. IKDC, Kujala and KOOS were administered to all patients pre-operatively and at 6-months and 1-year post-operatively. An anchor-based approach with a receiver-operator curve/area under the curve analysis using the Youden index was performed to calculate the MCID, SCB and PASS. The predictive power was determined to be acceptable with AUC≥70% and excellent with AUC≥80%.Results:From 2015 to 2018, 93 of 162 patients (mean age 23.7±10.1 years; 25 males, 68 females) completed for 6-month follow-up. At 6-months follow-up, SCB and PASS were defined with acceptable predictive power for all scores listed, while MCID achieved this for KOOS pain and sports subscores only (Table 1). At 1-year follow-up, SCB and PASS were each defined with acceptable predictive power for all scores listed, while MCID achieved this mark for KOOS pain and quality of life subscores as well as both Kujala scales.Conclusion:This study establishes MCID, SCB and PASS for IKDC, Kujala, and KOOS subscores at 6-months and 1-year postoperatively with excellent predictive power for 19/23 PROMs investigated at 1-year. These findings represent important benchmarks in patients undergoing primary MPFL reconstruction.

Failure Analysis in Patients With Patellar Redislocation After Primary Isolated Medial Patellofemoral Ligament Reconstruction.

Background:Reconstruction of the medial patellofemoral ligament (MPFL) has become a popular surgical procedure to address patellofemoral instability. As a consequence of the growing number of MPFL reconstructions performed, a higher rate of failures and revision procedures has been seen.Purpose:To perform a failure analysis in patients with patellar redislocation after primary isolated MPFL reconstruction.Study Design:Case series; Level of evidence, 4.Methods:Patients undergoing revision surgery for reinstability after primary isolated MPFL reconstruction were included. Clinical notes were reviewed to collect demographic data, information on the primary surgery, and the mechanism of patellar redislocation (traumatic vs nontraumatic). Preoperative imaging was analyzed regarding femoral tunnel position and the prevalence of anatomic risk factors (ARFs) associated with patellofemoral instability: trochlear dysplasia (types B through D), patella alta (Caton-Deschamps index >1.2, patellotrochlear index <0.28), lateralization of the tibial tuberosity (tibial tuberosity–trochlear groove distance >20 mm, tibial tuberosity–posterior cruciate ligament [TT-PCL] distance >24 mm), valgus malalignment (mechanical valgus axis >5°), and torsional deformity (internal femoral torsion >25°, external tibial torsion >35°). The prevalence of ARF was compared between patients with traumatic and nontraumatic redislocations and between patients with anatomic and nonanatomic femoral tunnel position.Results:A total of 26 patients (69% female) with a mean age of 25 ± 7 years were included. The cause of redislocation was traumatic in 31% and nontraumatic in 69%. Position of the femoral tunnel was considered nonanatomic in 50% of patients. Trochlear dysplasia was the most common ARF with a prevalence of 50%, followed by elevated TT-PCL distance (36%) and valgus malalignment (35%). The median number of ARFs per patient was 3 (range, 0-6), and 65% of patients had 2 or more ARFs. Patients with nontraumatic redislocations showed significantly more ARFs per patient, and the presence of 2 or more ARFs was significantly more common in this group. No significant difference was observed between patients with anatomic versus nonanatomic femoral tunnel position.Conclusion:Multiple anatomic risk factors and femoral tunnel malposition are commonly observed in patients with reinstability after primary MPFL reconstruction. Before revision surgery, a focused clinical examination and adequate imaging including radiographs, magnetic resonance imaging (MRI), standing full-leg radiographs, and torsional measurement with computed tomography or MRI are recommended to assess all relevant anatomic parameters to understand an individual patient’s risk profile. During revision surgery, care must be taken to ensure anatomic placement of the femoral tunnel through use of anatomic and/or radiographic landmarks.

Medial Patellofemoral Ligament Reconstruction Reduces Radiographic Measures of Patella Alta in Adults.

Background:Patellar height has long been considered a risk factor for patellofemoral instability. However, recent pediatric literature demonstrated a reduction in patellar height measurements following medial patellofemoral ligament (MPFL) reconstruction.Purpose:To assess the mean change in patellar height and the percentage of skeletally mature patients with patellar height ratios reduced to within-normal limits following MPFL reconstruction.Study Design:Case series; Level of evidence, 4.Methods:Adult patients undergoing primary MPFL reconstruction for recurrent lateral patellar instability between 2005 and 2013 were identified. Pre- and postoperative (within 1 year of surgery) lateral knee radiographs were assessed for patellar height indices, including Caton-Deschamps, Blackburne-Peel, and Insall-Salvati ratios. The change in patellar height and the number of patients reduced from abnormal to normal patellar height ratios following MPFL reconstruction were assessed.Results:Overall, 32 adult patients were included in the study, with a mean age of 25.7 years (range, 18-55 years). There were 21 women (66%) and 11 men (34%). Insall-Salvati, Blackburne-Peel, and Caton-Deschamps ratios all demonstrated significant reductions in patellar height between pre- and postoperative lateral knee radiographs (P < .001). All 3 indices showed a reduction in the number of patients meeting the criteria for patella alta following MPFL reconstruction. A total of 64% of patients had an abnormal preoperative Caton-Deschamps ratio reduced to within normal limits postoperatively.Conclusion:MPFL reconstruction provides a consistent reduction in patellar height measurements. The Caton-Deschamps ratio was reduced to the reference range following MPFL reconstruction in 64% of patients with preoperative patella alta. Surgeons treating patellofemoral instability should expect a reduction in patellar height after ligament reconstruction, which may affect the need for more invasive distalization procedures.