Role of Combined MPFL Reconstruction and Lateral Retinacular Release in Lateral Patellar Instability

By Muhammad Usama, Hafiz Umair Hussain, Faraz Ahmad Khan, Bilal Zaib, Abid Ullah, Muhammad Basharat

Affiliations

1. Department of Orthopaedics, Ghurki Trust Teaching Hospital, Lahore, Pakistan

doi: 10.29271/jcpsp.2025.06.730

ABSTRACT
Objective: To evaluate the efficacy of the combined medial patellofemoral ligament (MPFL) and reconstruction release in lateral patellar instability in terms of radiological and functional outcomes following the procedure.
Study Design: A retrospective observational study.
Place and Duration of the Study: Department of Orthopaedics, Ghurki Trust Teaching Hospital, Lahore, Pakistan, from January 2019 to January 2024.
Methodology: Forty-seven patients with lateral patellar instability that underwent MPFL reconstruction and lateral retinacular release were studied, and the average follow-up duration was 17.5 (12–26) months. The patellar tilt, lateral patellar, and congruence angles were determined. Globally accepted scoring systems—such as Kujala, Lyshom, and Nelitz scores—were computed and compared.
Results: Congruence angle improved from 18.7 ± 4.8 to a value of -4.9 ± 1.37 postoperatively. On the last follow-up, the lateral patellar angle had improved from 7.9 ± 3.9 to 6.1 ± 2 which was statistically significant (p <0.05) according to the paired samples t-test evaluation. Additionally, the patellar tilt angle improved, going from 27.6 ± 6.7 to 6.1 ± 0.9. In addition to the radiological improvement, an increase in each of the three measured scores indicated physiological improvement. The postoperative mean Lyshom score increased considerably from 43.82 ± 11.3 to 87.74 ± 8.85 (p <0.001). Likewise, the average Kujala score increased significantly from 45.42 ± 9.29 points to 89.42 ± 6.99 (p <0.001). Eighteen (38%) patients reported as being satisfied, four (9%) patients were partially satisfied, and only one (2%) patient was not satisfied.
Conclusion: Improvements in both radiological and functional outcomes occur with MPFL reconstruction and lateral retinacular release; nonetheless, further higher-level evidence-generating research on the topic is recommended.

Key Words: Lateral retinacular release, Medial patello-femoral ligament reconstruction, Patellar instability.

INTRODUCTION

Inadequate recognition and treatment of patellar instability can result in profound long-term implications. It is a prevalent and incapacitating disorder. The two types of patellofemoral instability—dislocation and subluxation—have significant recurrence rates. Patella dislocation or subluxation patients may have chronic knee discomfort, functional restrictions, and arthritic degeneration of the patellofemoral articulation, even in the absence of recurrent instability.^1-3 

In patients with normal patellar height and tibial tubercle- trochlear groove (TT-TG) distance, medial patello-femoral ligament (MPFL) reconstruction has been established as a standard surgical approach for treating recurrent patellar instability due to its critical role in limiting the lateral shift of the patella and the high incidence of avulsion of MPFL with primary patellar dislocation.

However there is debate regarding the necessity and the indications of MPFL reconstruction procedure, as well as lateral retinacular release (LRR).^4,5 Early in the course of therapy, conservative treatment is frequently used; nevertheless, symptomatic patellar instability may continue and need surgical intervention. The combined lateral retinacular release and reconstruction of the MPFL is one surgical strategy that has been established.² The impact of LRR in conjunction with MPFL reconstruction has been thoroughly examined in many studies.^3,4 Malatray et al. compared the results of individual MPFL reconstructions with MPFL reconstruction in conjunction with LRR in patients with persistent patellar instability in a randomised control experiment.⁶

Reconstruction of the MPFL, the principal soft tissue stabiliser of the patella, has become a standard procedure for surgical management of patellar instability. This MPFL reconstruction re-establishes the medial constraint of the patella. On the other hand, release of the lateral retinaculum treats excessive lateral patellar tilt and displacement. Thus, patients with lateral patellar instability benefit from a combined strategy of lateral retinacular release and MPFL reconstruction. When compared to each operation alone, this method may yield better results since it addresses the medial and lateral soft tissue abnormalities that lead to patellar instability.⁷ In patients with a Q-angle of less than 20° and TT-TG of less than 20 mm, it was found that, LRR in addition to MPFL reconstruction helps in improving the knee joint function. Moreover, there is reduction in pre- to post- operative Lysholm’s grade after the inclusion of lateral retinacular release.^8-11

The need for this study is based on the fact that management of lateral patellar instability is due to failure in both the static and dynamic stabilisers in the knee joint. MPFL plays a crucial role in preventing lateral patellar shift, and reconstruction of it is often performed. Continuing the lateral retinacular release is an attempt to enhance the flexibility around the patella in order to balance the forces that influence its movement. This study aimed to measure the efficacy of combined MPFL reconstruction and lateral retinacular release in lateral patellar instability in terms of radiological and functional outcomes following the procedure. These insights are likely to aid in ascertaining whether such a combination strategy presents significant advantages, thereby providing direction to the surgeons for enhancing the treatment recommendations to yield better postoperative results.

METHODOLOGY

This retrospective descriptive case series study analysed patients with lateral patellar instability who underwent medial patellofemoral ligament (MPFL) reconstruction alongside LRR at the Department of Orthopaedics, Ghurki Trust Teaching Hospital, Lahore, Pakistan, over a period of five years, i.e., from January 2019 to January 2024. The data were retrieved by the Hospital Management Information System (HMIS) and the hospital’s own database associated with it. Ethical approval was obtained from the Ethics Committee of Ghurki Trust Teaching Hospital, Lahore, Pakistan, and informed consent was acquired from all participants. A positive preoperative patellar apprehension test, a preoperative MRI demonstrating an MPFL rupture, a history of two or more prior patellar dislocations with poor outcomes after conservative therapy, and the presence of unrelieved knee discomfort were the inclusion criteria for the research. In accordance with the study's criteria, patients were included in the study, provided their complete medical records were accessible. An open distal femur epiphysis, first patellar dislocation, injuries to the anterior and posterior cruciate ligaments, medial and lateral collateral ligaments, meniscus (grade II or higher tear) or knee cartilage (grade III or IV) injury were among the exclusion criteria. Patients with severe trochlear dysplasia (Dejour types B to D), high patella (Insall-Salati Ratio >1.2), femoral anteversion angle (FAA) ≥30°, tibial tubercle-trochlear groove (TT-TG) distance >20 mm, or knee joint infection were excluded as well. With a mean follow-up duration of more than 12 months, the final sample size included 47 patients.

In all patients, the authors employed a combined surgical technique of MPFL reconstruction and lateral retinacular release to address lateral patellar instability. Patients were positioned supine on the operating table with a tourniquet applied to the proximal thigh to ensure a bloodless surgical field. General or regional anaesthesia was administered based on the patient's condition and the surgeon's preference. A thorough examination under anaesthesia was conducted to confirm patellar instability and assess the range of motion. A longitudinal midline skin incision was made over the patella, extending from the proximal end of patella to just below the tibial tubercle. The subcutaneous tissue was dissected, and the extensor mechanism was exposed. Using an arthroscopic or open technique, the lateral retinacular release was performed. The lateral retinaculum was incised longitudinally to release tight lateral structures and alleviate lateral patellar tension, taking care to preserve the superior lateral genicular artery to prevent compromising the blood supply to the patella. A gracilis or semitendinosus tendon graft was harvested from the ipsilateral knee. The graft was prepared by removing muscle tissue and fashioning it to the desired length and diameter. Two small incisions were made, one at the medial aspect of the patella and another at the medial femoral epicondyle. Bone tunnels were created at the insertion sites using a drill. The tunnel at the patella was positioned at the superomedial border, and the femoral tunnel was placed at the anatomic insertion of the MPFL. The prepared tendon graft was passed through the bone tunnel at the patella and secured using an interference screw or suture anchor. The other end of the graft was then passed through the femoral tunnel and similarly secured (Figure 1).

The knee was taken through a range of motion to ensure appropriate graft tension and to confirm patellar tracking. Adjustments were made as necessary to achieve optimal tension without over-tightening the graft. Final fixation was done using interference screws or suture anchors at both the patellar and femoral insertion sites. The surgical incisions were irrigated and closed in layers. Subcutaneous tissue was approximated with absorbable sutures, and the skin was closed with non-absorbable sutures or staples. A sterile dressing was applied, and the knee was placed in a brace to maintain extension. Early range of motion exercises were initiated within the first week postoperatively to prevent stiffness. Weight-bearing was gradually increased as tolerated, with the use of crutches initially. A structured physical therapy programme was followed to restore strength and function. Regular follow-up visits were scheduled to monitor healing and assess the stability and function of the patella. Clinical outcome scores (e.g., Kujala, Lysholm) and radiographic evaluations  were  performed  to  document  improvements.

All the data were entered and analysed using SPSS version 26. Quantitative variables were presented in terms of measures of central tendencies (mean and standard deviations); whereas qualitative variables were presented in frequencies and percentages. After analysing the data for assumptions of paired samples t-test, including continuous normal distribution with homogeneity, the aforementioned test was applied. As readings from each individual were taken at two points in time and were independent of other subjects’ paired samples t-test was applied to compare pre- and post-operative results, taking a p-value less than 0.05 as significant.

Table I: Demographic profile of patients (n = 47).

Variables	n	(%)	Mean ± SD (Range)
Male	25	53.2
Female	22	46.8
Age (years)			26.98 ± 6.30 (17-38)
Follow-up period (months)			17.70 ± 4.33 (12-26)

Table II: Preoperative and postoperative clinical and radiological parameters.

Variables	Preoperative Mean (SD)	Postoperative Mean (SD)	*p-value
Kujala score	45.42 ± 9.29	89.42 ± 6.99	<0.001
Lysholm score	43.82 ± 11.53	87.74 ± 8.85	<0.001
Congruence angle	18.7 ± 4.8	-4.9 ± 0.7	0.024
Lateral patellar angle	7.9 ± 3.9	6.1 ± 2	0.047
Patellar tilt angle	27.6 ± 6.7	6.1 ± 0.9	0.042
*Paired sample t-test was used.

RESULTS

The study included a total of 47 patients. Demographic breakdown revealed a slight male predominance, with 25 (53.2%) males and 22 (46.8%) females. The mean age of the patients was 26.98 ± 6.30 years, indicating a relatively young cohort (age range: 17-38 years). The average follow-up period for these patients was 17.70 ± 4.33 months, ranging from 12 to 26 months (Table I).

The comparison of preoperative and postoperative clinical scores and radiological parameters demonstrated significant improvements following the combined surgical procedure. There was a significant increase in functional Kujala score pre- and postoperatively (45.42 ± 9.29) and (89.42 ± 6.99, p <0.001), respectively. Similarly, the Lysholm score, which evaluates knee stability and symptoms, improved markedly from a preoperative mean of 43.89 ± 11.53 to a postoperative mean of 87.74 ± 8.85, also with a p-value of <0.001 (Table II).

Radiologically, the congruence angle improved significantly from a preoperative mean of 18.7 ± 4.8 degrees to a postoperative mean of -4.9 ± 1.37 degrees, with a p-value of 0.024 indicating a correction toward normal patellar alignment. The lateral patellar angle, indicative of patellar tilt, improved from a preoperative mean of 7.9 ± 3.9 degrees to a postoperative mean of 6.1 ± 2.7 degrees, with a p-value of 0.047, showing a significant reduction in patellar tilt. Additionally, the patellar tilt angle itself showed a substantial decrease from preoperative to postoperative with a p-value of 0.042, signifying a significant correction of the patellar tilt.

Patient satisfaction, as assessed by the Nelitz criteria, revealed that a majority of the patients were pleased with the outcomes of the procedure. Specifically, 24 (51%) patients reported being very satisfied with their knee function, noting a substantial improvement compared to their preoperative status. Eighteen (38%) patients reported being satisfied, indicating improved knee function without episodes of subluxation. Four (9%) patients were partially satisfied, experiencing improved knee function but still feeling apprehensive. Only 1 (2%) patient reported being not satisfied, experiencing no improvement and continued episodes of patellar subluxation.

Figure 1: MPFL fixation: (A) Schottle’s point: Radiographic marked site of femoral tunnel placement. (B) Drilling of the aforementioned tunnel and placement of a guide wire. (C) Passage of a graft and femoral fixation. (D-E) Fixation at the patella with the use of the two strands.

This high level of satisfaction underscores the perceived effectiveness of the combined MPFL reconstruction and lateral retinacular release procedure from the patient's perspective.

DISCUSSION

There is an ongoing discussion on the efficacy of lateral retinacular release (LRR) in conjunction with MPFL reconstruction in the management of lateral patellar instability. While some trials have yielded encouraging results, others have not been able to show a clear clinical improvement when compared to isolated MPFL reconstruction.^12-14

Migliorini et al. conducted a systematic study that examined the available biomechanical and clinical data pertaining to the role of LRR in conjunction with MPFL reconstruction. A total of 2,131 knees from 63 papers were included in the study, with a mean follow-up of 40.87 ± 24.1 months. When comparing MPFL reconstruction alone to the combined MPFL reconstruction and LRR group, the authors discovered that all patient-reported outcome measures (PROMs) improved, with statistically significant differences in Kujala (+3.8%, p = 0.01) and Lysholm (+4.2%, p = 0.004) in the combined MPFL reconstruction and LRR group.⁹ This study’s results are consistent with this research. As in this study, significant improvement was observed in clinical and radiological outcomes. In comparable research, Wenhao et al. found that all 50 patients (52 knees) who underwent MPFL reconstruction alongside LRR had substantial improvement in the Lysholm score (48.17 ± 9.52 to 91.88 ± 5.07) and Kujala score (51.40 ± 14.39 to 92.23 ± 4.74).¹⁰

On the other hand, Bedi et al.'s finite element analysis research looked at how lateral release affects patellar stability following an MPFL reconstruction. Researchers found that lateral release decreased the force needed to move the patella 1 cm laterally by 7-11%.¹⁵ A more recent study by Waters et al. was unable to show a significant difference in failure rates or functional outcome between MPFL reconstruction surgery performed alone and in conjunction with LRR.^4,16

The investigation conducted by Rhatomy et al. revealed that eight individuals exhibited a noteworthy improvement in their clinical results following minimally invasive MPFL reconstruction with LRR.¹⁷ The Lysholm score increased with (p= 0.011), from 64.37 ± 8.23 to 90.87 ± 3.23 and the Kujala score rose to 88.37 ± 4.34 (p < 0.001) from 60.87 ± 7.94. A systematic review concluded that Kujala score from 12 case series revealed a mean of 87.7 (95% CI: 85.15-90.39) after MPFL reconstruction.¹⁸ Using synthetic grafts, Nomura et al. showed an increase in Kujala score from 63.2 to 94.2 in their surgical cohort.¹⁹ A study conducted in the same city as the current study also concluded that MPFL reconstruction resulted in significant clinical improvement as judged by international knee documentation criteria (IKDC).²⁰

In the current study, the congruence angle improved significantly from a preoperative mean of 18.7 ± 4.8 degrees to a postoperative mean of -4.9 ± 1.37 degrees, with a p-value of 0.024 indicating a correction towards normal patellar alignment. The lateral patellar angle, indicative of patellar tilt, improved from a preoperative mean of 7.9 ± 3.9 degrees to a postoperative mean of 6.1 ± 2.7 degrees, with a p-value of 0.047, showing a significant reduction in patellar tilt. Additionally, the patellar tilt angle itself showed a substantial decrease from preoperative to postoperative with a p-value of 0.042, signifying a significant correction of the patellar tilt. These findings are in concordance with those of Li et al. Li et al. inferred that the congruence angle improved significantly from 19.2 ± 6.3° before surgery to −6.0 ± 0.5° at the last follow-up. The lateral patellar angle also showed significant improvement, changing from −6.9 ± 3.5° before surgery to 5.1 ± 2.4° at the last follow-up. Similarly, the patellar tilt angle saw a notable improvement, moving from 24.5 ± 5.2° before surgery to 12.3 ± 1.9° at the final follow-up.²¹

There are several noteworthy strengths of the study. It starts with extensive data gathering and analysis of radiological and functional results, yielding a solid assessment of the surgical process. The results are given more credibility, and cross- study comparisons are made easier by the utilisation of widely accepted scoring systems such as Kujala, Lysholm, and Nelitz. Further evidence of the combination procedures’ effectiveness comes from the study's statistically significant increase in clinical ratings and radiological markers. An essential source of information on the surgery's medium-term effects is the 17.5-month longitudinal follow-up phase. From the patients' point of view, the surgery was safe and success-ful, as evidenced by the high levels of patient satisfaction and lack of significant problems.

However, the following limitations were noted in the study. The study had a retrospective design, which increases the risk of selection and recall bias. Relatively smaller sample size and lack of a control (comparison) group in which only MPFL reconstruction was done, limit the generalisation of this study’s results. Moreover, the study has the limitation of being conducted in a single centre. Further multicentric research needs to be carried out (especially randomised control trials) to compare the outcomes of patients treated with both procedures, MPFL and LRR vs. those treated only with MPFL reconstruction to provide more robust data. Moreover, subsequent biomechanical analysis of the proposed combined procedure can reveal more information on the physiological effects of the operation, complementing the clinical evidence. Concentrating on these aspects will assist in improving and defining the management of lateral patellar instability more effectively.

CONCLUSION

The study shows a significant improvement in the stability is linked to the combination of MPFL reconstruction and lateral release. Improvements in both radiological and functional outcomes are linked to the technique; nonetheless, further research on the topic of higher-level evidence-generating study designs is recommended.

ETHICAL APPROVAL:
Ethical approval was obtained from the Ethics Committee of Ghurki Trust Teaching Hospital, Lahore, Pakistan.

PATIENTS’ CONSENT:
A written consent was obtained from all the patients included in the study.

COMPETING INTEREST:
The authors declared no conflict of interest.

AUTHORS’ CONTRIBUTION:
MU, HUH: Jointly proposed the study, analysed the data and prepared the final draft.
FAK, BZ, AU, MB: Contributed to the data design and interpretation of the study, alongside preparation and critical review of the final draft
All authors approved the final version of the manuscript to be published.

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