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To evaluate the recurrent dislocation risk and patient-reported outcomes of peroneus longus allograft tissue for medial patellofemoral ligament (MPFL) reconstruction.
Methods
Patients who underwent MPFL reconstruction with peroneus longus allograft at an academic center between 2008 and 2016 were identified. Record review and patient contact were used to identify any cases of recurrent patellar dislocation and collect patient-reported outcomes scores (Knee injury and Osteoarthritis Outcome Score [KOOS], Norwich Patellar Instability score, Marx activity scale). Patients with 1-year minimum follow-up were included. Outcomes were quantified and the proportion of patients reaching a previously defined patient acceptable symptom state (PASS) for patellar instability was determined.
Results
Sixty-one patients (42 female and 19 male) underwent MPFL reconstruction with peroneus longus allograft during the study period. Forty-six patients (76%) with 1-year minimum follow up were contacted at a mean of 3.5 years postoperative. The mean age at time of surgery was 22 ± 7.2 years. Patient-reported outcomes data were available in 34 patients. Mean KOOS subscale scores were as follows: Symptoms 83.2 ± 19.1, Pain 85.2 ± 17.6, Activities of Daily Living 89.9 ± 14.8, Sports 75 ± 26.2, and Quality of Life 72.6 ± 25.7. The mean Norwich Patellar Instability score was 14.9% ± 17.4%. The mean Marx activity score was 6.0 ± 5.2. No recurrent dislocations were noted during the study period. Sixty-three percent of patients who underwent isolated MPFL reconstruction met PASS thresholds in at least 4 of 5 KOOS subscales.
Conclusions
The use of a peroneus longus allograft in MPFL reconstruction in conjunction with other indicated procedures results in a low re-dislocation risk and a high proportion of patients meeting PASS criteria for patient-reported outcome scores 3 to 4 years postoperatively.
Level of Evidence
IV, case series.
Patellar dislocations are relatively common knee injuries,
The MPFL is the primary soft-tissue restraint to lateral patellar translation, and MPFL injuries decrease the force required to laterally dislocate the patella.
In patients with recurrent episodes of instability, surgical treatment is indicated to restore knee stability and function. In many patients with recurrent instability, isolated MPFL reconstruction has been shown to be an effective procedure in reducing recurrence risk and instability symptoms.
Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent lateral patellar dislocations: A systematic review and meta-analysis.
Graft choice in isolated medial patellofemoral ligament reconstruction: A systematic review with meta-analysis of rates of recurrent instability and patient-reported outcomes for autograft, allograft, and synthetic options.
Influence of graft source and configuration on revision rate and patient-reported outcomes after MPFL reconstruction: A systematic review and meta-analysis.
Systematic review of medial patellofemoral ligament reconstruction techniques: Comparison of patellar bone socket and cortical surface fixation techniques.
While the results of isolated MPFL reconstruction are generally good in appropriately selected patients, multiple grafts have been described, and there are limited data to suggest the superiority of any particular graft type.
Medial patellofemoral ligament reconstruction with allograft versus autograft tissue results in similar recurrent dislocation risk and patient-reported outcomes.
Graft choice in isolated medial patellofemoral ligament reconstruction: A systematic review with meta-analysis of rates of recurrent instability and patient-reported outcomes for autograft, allograft, and synthetic options.
Medial patellofemoral ligament reconstruction with allograft versus autograft tissue results in similar recurrent dislocation risk and patient-reported outcomes.
; however, most published series of allograft tissue use hamstring allograft tissue. Although other allograft options including peroneus longus have been described, published outcomes are lacking.
A recent biomechanical study demonstrated that and peroneus longus tendon exhibited noninferior initial biomechanical strength and stiffness characteristics compared with tibialis anterior allograft tendon.
Therefore, similar clinical outcomes after MPFL reconstruction using peroneus longus tendon are anticipated. An outcome study of this graft type is important to demonstrate that clinical results match the anticipated positive results. The purpose of this study is to evaluate the recurrent dislocation risk and patient-reported outcomes of peroneus longus allograft tissue for MPFL reconstruction. We hypothesized that MPFL reconstruction with peroneus longus allograft would result in a low recurrent dislocation risk and good patient-reported outcomes.
Methods
Patients and Follow-up
Following institutional review board approval (The Ohio State University; 2015H0446), a search of medical records using Current Procedural Terminology codes and operative report review was undertaken to identify patients who underwent MPFL reconstruction with a peroneus longus allograft by 2 sports medicine fellowship–trained orthopaedic surgeons (R.A.M. and D.C.F.) between January 2008, and December 2016. All patients who underwent MPFL reconstruction with peroneus longus allograft during this period were eligible for study inclusion.
Surgical Indications
Surgical management of patellar instability was offered to patients with recurrent lateral patellar instability. MPFL reconstruction was performed in all cases, with additional procedures performed at surgeon discretion following discussion with the patient. General indications for associated procedures were as follows. Lateral retinacular release or lengthening was performed in patients in whom the patellar could not be everted to the level of the horizon on physical examination under anesthesia. Tibial tubercle osteotomy (TTO) was considered in patients with patellar maltracking manifested as a large j-sign
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.
). Anteromedialization TTO was performed in such patients if the tibial tubercle–trochlear groove (TT-TG) distance was greater than 16 to 20 mm and distalization TTO was performed in the setting of patella alta with a Caton–Deschamps Index greater than 1.20 to 1.30.
Surgical Procedure and Rehabilitation
A diagnostic arthroscopy was performed in each case to identify and treat any intra-articular pathology. If indicated, TTO was then performed to anteromedialize and/or distalize the tubercle as dictated by patient anatomy. Any lateral-sided procedures such as lateral retinacular lengthening or release were then performed via an open approach based on intraoperative evaluation of patellar eversion.
MPFL reconstruction was then performed via an open approach. Following an incision over the medial patellar border, the interval just superficial to the capsular layer was identified and bluntly dissected to the adductor tubercle. A second incision was made over the adductor tubercle and a suture was passed through the resultant soft tissue tunnel for graft passage. Two anchors were placed on the medial patellar border with fluoroscopic guidance to ensure placement in the proximal half of the patella, and a shallow bone trough was created between the anchors. A femoral tunnel 7 mm in diameter was then placed anatomically on the saddle between the adductor tubercle and medial epicondyle following fluoroscopic confirmation that the location corresponded with Schottle’s point
(Fig 1) and confirmation of relative isometry. The tunnel was drilled proximally and anteriorly to a maximal depth without violating the opposite cortex. No patients with open physes that required adjustment of tunnel trajectory underwent MPFL reconstruction with peroneus longus grafts in this period. The peroneus longus allograft was prepared by trimming and whip-stitching the 2 free ends such that they could pass together through the 7-mm femoral tunnel. This generally resulted in a graft diameter of approximately 5 mm. The graft was attached to the patella in its center with the 2 previously placed anchors and the free ends were passed through the soft-tissue tunnel and docked into the femoral tunnel. Fixation was performed at 60 to 75° of knee flexion with an interference screw and no graft tension.
Fig 1Lateral fluoroscopic image demonstrating identification of the starting point of the MPFL femoral tunnel according to the technique of Shottle et al.
Postoperative rehabilitation varied depending on whether a concomitant TTO was performed. In the case of isolated MPFL reconstruction, immediate weight-bearing with crutches was allowed with progression to unassisted gait when quadriceps control and strength were sufficient that the patient could walk without a limp. Jogging was allowed at 3 months with return to sports between 4 and 6 months postoperatively. In the case of TTO, weight-bearing was limited for 4 to 6 weeks postoperatively with a hinged knee brace on and locked in extension while ambulating. Full weight-bearing was allowed at 4 to 6 weeks, and the brace was discontinued at 8 weeks. High-impact activities such as running were limited for 6 months postoperatively and until well healed osteotomy site was noted on plain films.
Data Collection
Chart review was completed and demographic, surgical, and follow-up data were extracted including patient age, sex, body mass index, radiographic parameters, associated surgical procedures, and any subsequent patellar instability or patellofemoral surgery. Radiographic measures included the Caton–Deschamps Index
These measurements were performed by a single sports medicine fellowship–trained orthopaedic surgeon (R.A.M.) based on the published methods previously.
Patients were subsequently contacted by mail and/or telephone and asked about recurrent patellar dislocation episodes and surgery. Patients also were asked to complete outcome scores including the Knee Injury and Osteoarthritis Outcome Score (KOOS),
Summary statistics were calculated. These included mean and standard deviations for normally distributed, continuous variables and proportions for categorical variables. Patient acceptable symptoms state (PASS) criteria are established to identify the score above which patients with a given condition are satisfied with their symptoms. The PASS is specific to each outcome score as well as to individual patient populations. A recently published study developed PASS thresholds for each KOOS subscale for patients 1 year following isolated MPFL reconstruction.
The minimal clinically important difference, substantial clinical benefit, and patient-acceptable symptomatic state after medial patellofemoral ligament reconstruction.
The minimal clinically important difference, substantial clinical benefit, and patient-acceptable symptomatic state after medial patellofemoral ligament reconstruction.
All calculations were performed using Microsoft Excel (Redmond, WA).
Results
A total of 63 knees in 61 patients were treated for recurrent patellar instability with a primary MPFL reconstruction during the study period. The study population was young and majority female (Table 1). The population included 30 knees (47%) with patella alta, 12 knees (21%) with a TT-TG distance greater than 20 mm, and 45 knees (71%) with trochlear dysplasia (Table 1). Concomitant procedures included 1 partial medial meniscectomy, 19 partial lateral meniscectomies, 1 lateral meniscus repair, 16 tibial tubercle osteotomies, 10 lateral retinacular lengthenings, 12 lateral retinacular releases, one lateral retinacular repair, 18 loose body removals, 16 microfractures, and 23 chondroplasties.
Table 1Demographics
Sex
Male
19 (31%)
Female
42 (69%)
Age, y
22.0 ± 7.2
BMI
27.8 ± 732
Caton–Deschamps Index
1.20 ± 0.15
TT-TG distance, mm
17.1 ± 4.3
Trochlear dysplasia
None
18 (29%)
Dejour A
38 (60%)
Dejour B
7 (11%)
Dejour C or C
0 (0%)
BMI, body mass index; TT-TG, tibial tubercle–trochlear groove.
Of the 61 patients (63 MPFL reconstructions) eligible for study inclusion, 46 patients (48 reconstructions) with minimum 12-month follow-up (76%) were available for follow-up at a mean of 3.5 years (range 1.0-6.7 years) postoperative. During the follow-up period, no episodes of recurrent patellar dislocation were noted, but subjective postoperative patellar subluxation was reported by 12 patients (25%).
Patient-reported outcomes data were available in 34 patients (36 MPFL reconstructions; 57%) at a mean of 4.1 years (range 1.2-6.7 years) following surgery. The mean Norwich Patellar Instability score was 14.9% ± 17.4%. The mean KOOS subscales were Symptoms: 83.2 ± 19.1, Pain: 85.2 ± 17.6, Activities of Daily Living: 89.9 ± 14.8, Sport/Recreation Function: 75 ± 26.2, and Knee-Related Quality of Life: 72.6 ± 25.7. The mean Marx activity score was 6.0 ± 5.2 (Table 2).
Table 2Postoperative Patient-Reported Outcomes
Overall
Isolated MPFLR N = 25
MPFLR + TTO N = 11
Significance
KOOS Symptoms
83.2 ± 19.1
84.3 ± 17.5
80.3 ± 23.5
P = .57
KOOS Pain
85.2 ± 17.6
84.8 ± 16.4
85.5 ± 21.4
P =.91
KOOS ADL
89.9 ± 14.8
90.1 ± 14.6
88.5 ± 15.9
P =.75
KOOS Sport
75.0 ± 26.2
77.3 ± 28.2
70.9 ± 23.6
P =.52
KOOS QoL
72.6 ± 25.7
76.6 ± 24.9
63.6 ± 27.5
P =.20
Norwich Patellar Instability Score
14.9% ± 17.4%
13.3% ± 16.6%
16.9% ± 20.0%
P =.56
Marx Activity Score
6.0 ± 5.2
7.1 ± 5.4
3.7 ± 4.4
P =.076
ADL, Activities of Daily Living; KOOS, Knee injury and Osteoarthritis Outcome Score; MPFLR, medial patellofemoral ligament reconstruction; QoL, Quality of Life; TTO, tibial tubercle osteotomy.
Using established PASS thresholds, we found that the percentage of patients who underwent isolated MPFL reconstruction who achieved the PASS threshold for each KOOS subscale was 71% for Symptoms, 63% for Pain, 38% for Activities of Daily Living , 67% for Sport/Recreation Function, and 83% for Quality of Life (Table 3). Sixty-three percent of patients who underwent isolated MPFL reconstruction met PASS thresholds in at least 4 of 5 KOOS subscales.
Table 3KOOS Subscales and Percentage of Patients Meeting PASS After Isolated MPFLR
Mean ± SD
PASS Threshold
Percentage Meeting PASS
KOOS Symptoms
84.3 ± 17.5
80.4
71%
KOOS Pain
84.8 ± 16.4
84.7
63%
KOOS ADL
90.1 ± 14.6
99.3
38%
KOOS Sport
77.3 ± 28.2
57.5
67%
KOOS QoL
76.6 ± 24.9
53.1
83%
ADL, Activities of Daily Living; KOOS, Knee injury and Osteoarthritis Outcome Score; MPFLR, medial patellofemoral ligament reconstruction; PASS, patient acceptable symptom state; QoL, Quality of Life; SD, standard deviation.
The primary finding of this study is that MPFL reconstruction with peroneus longus allograft in conjunction with other indicated procedures results in a low dislocation risk and a high proportion of patients meeting PASS criteria for patient-reported outcome scores in patients with recurrent patellar instability. Previous work has demonstrated allograft to be a viable alternative to autograft tissue for MPFL reconstruction. In a recent systematic review comparing outcomes of autograft and allograft MPFL reconstruction, Hendawi et al.
found that in a pediatric population the autograft group had longer operative times, greater risk of graft failure, and lower patient-reported outcomes. Other recent work in adults found no increased risk of recurrent instability or poorer patient-reported outcomes with allograft tissue.
Medial patellofemoral ligament reconstruction with allograft versus autograft tissue results in similar recurrent dislocation risk and patient-reported outcomes.
Allograft use avoids graft-site morbidity and preserves autograft tissue for potential future intra-articular procedures where such grafts have been shown to be superior.
The results of the current study compare favorably to previously published series. A recent study by Mulliez et al.
evaluated the outcomes of gracilis autograft MPFL reconstruction with TTO added as indicated in a similar population to the current study. The reported KOOS Pain, Activities of Daily Living, and Symptom subscales range from 75 to 83 and KOOS Sport and knee–related Quality of Life subscales of 55 and 58, respectively. In a similar study using an algorithmic approach to the addition of TTO to MPFL reconstruction with semitendinosus allograft, Dragoo et al.
reported KOOS Pain, Activities of Daily Living, and Symptom subscales ranging from 65 to 80 and KOOS Sport and knee-related Quality of Life subscales of 49 and 46, respectively. The outcomes of the current study compare favorably with these results. The very low risk of recurrent patellar dislocation (0%) compares favorably with the 1% to 2% failure risk of both isolated MPFL reconstructions and several published series in which a tibial tubercle osteotomy was performed in addition to MPFL reconstruction.
Medial patellofemoral ligament reconstruction combined with distal realignment for recurrent dislocations of the patella: 5-year results of a randomized controlled trial.
Further, the results of this study are generally positive in term of the proportion of patients who met the PASS threshold in the majority of KOOS subscales for this study. The purpose of PASS is to define a threshold in which a patient-reported outcome corresponds to an acceptable state regarding knee satisfaction postoperatively. In each KOOS subscale except for Activities of Daily Living, at least 63% of patients exceed the PASS threshold.
Previous studies have compared the failure load and stiffness of the native MPFL with other graft options, including peroneus longus, semitendinosus, gracilis, and tibialis anterior. Duchman et al.
demonstrated greater lateral restraining force at increased displacement in MPFL reconstruction compared with the intact MPFL due to a much greater failure load and stiffness of the tibialis anterior allograft used in the study compared with the native MPFL. Previous work has shown greater failure load and stiffness of both semitendinosus and gracilis tendon grafts
showed that the average failure load of the anterior half of peroneus longus tendon was similar to semitendinosus and superior to gracilis tendons. These demonstrate that all available grafts likely have sufficient strength for MPFL reconstruction. The good outcomes of peroneus longus in the current study suggest that the graft is not overly stiff as to cause over constraint.
Limitations
There are several limitations of the current study. One major limitation is that although 75% of patients were available for assessment of recurrent dislocation risk at a minimum of 1-year postoperatively, only 57% of eligible patients completed patient-reported outcome scores. This loss to follow-up may introduce selection bias into the collected data. Some outcomes data were collected by phone, which in some cases has been shown to potentially alter responses as compared to independent form completion.
The data were collected by an investigator who was not the surgeon to minimize this potential bias. Further, the study population and procedures performed and rehabilitation were quite heterogeneous. Although this heterogeneity complicates comparison of these outcomes with previous published work, it also makes these data broadly generalizable. Similarly, although all grafts were frozen and not terminally irradiated, specific graft details including size and donor age are not available in this cohort, limiting the ability to evaluate impacts of these factors on outcomes. These data demonstrate the effectiveness of peroneus long allograft in treating a large spectrum of patellofemoral instability pathology via MPFL reconstruction—with or without tibial tubercle osteotomy. Further, the study lacks a control group. Comparisons to MPFL reconstructions performed using other grafts in other populations do provide some context for the outcomes presented in this study, but potential differences in patient populations and surgical technique limit these comparisons. Finally, preoperative outcome scores are lacking in this cohort. Their absence limits the analysis to postoperative findings and precludes assessment of improvement over time as well as calculation of the proportion of patients who achieved minimum clinically important differences in terms of improvements of the outcome scores with surgery. Calculation of the proportion of patients achieving PASS mitigates but does not eliminate this limitation.
Conclusions
The use of a peroneus longus allograft in MPFL reconstruction in conjunction with other indicated procedures results in a low redislocation risk and a high proportion of patients meeting PASS criteria for patient-reported outcome scores 3 to 4 years postoperatively.
Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent lateral patellar dislocations: A systematic review and meta-analysis.
Graft choice in isolated medial patellofemoral ligament reconstruction: A systematic review with meta-analysis of rates of recurrent instability and patient-reported outcomes for autograft, allograft, and synthetic options.
Influence of graft source and configuration on revision rate and patient-reported outcomes after MPFL reconstruction: A systematic review and meta-analysis.
Systematic review of medial patellofemoral ligament reconstruction techniques: Comparison of patellar bone socket and cortical surface fixation techniques.
Medial patellofemoral ligament reconstruction with allograft versus autograft tissue results in similar recurrent dislocation risk and patient-reported outcomes.
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.
The minimal clinically important difference, substantial clinical benefit, and patient-acceptable symptomatic state after medial patellofemoral ligament reconstruction.
Medial patellofemoral ligament reconstruction combined with distal realignment for recurrent dislocations of the patella: 5-year results of a randomized controlled trial.
The authors report the following potential conflicts of interest or sources of funding: D.C.F. reports personal fees from DePuy Mitek, Smith & Nephew, Vericel, Ceterix, Conmed, Histogenics, and Zimmer, outside the submitted work. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
Investigation performed at the Sports Medicine Research Institute, The Ohio State University, Columbus, Ohio, U.S.A.
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