Non-absorbable surgical sutures versus autologous tendons in the reconstruction of medial patellofemoral ligaments: a randomised controlled trial protocol
Patellar dislocation refers to the lateral displacement of the patella from the femoral condylar glide groove. Adolescents are the predominant demographic affected, with an incidence rate ranging from approximately 5.8–77.8 per 100 000 individuals. Acute cases are typically associated with a history of twisting or falling, and lateral dislocations are the most frequent. In the absence of proper treatment, approximately 30%–60% of patients may progress to recurrent patellar dislocations, subluxations or functional instability secondary to pain. Recurrent patellar dislocations often necessitate surgical intervention due to joint pain, instability and potential damage to the patellofemoral joint cartilage. Surgical interventions for recurrent patellar dislocations encompass tibial tuberosity osteotomy, femoral trochleoplasty and soft tissue reconstructions, such as medial patellofemoral ligament reconstruction (MPFLR). Several studies have established that over 90% of patients with lateral patellar dislocations exhibit concurrent injury to the MPFL. Consequently, arthroscopic-assisted MPFLR has been widely recognised as the preferred method for treating acute or recurrent patellar dislocations, owing to its advantages of reduced surgical trauma, minimal vascular and nerve injury, and satisfactory postoperative outcomes. MPFLR can be achieved using autografts, allografts or artificial synthetic materials, with the autografts typically being the gracilis, semitendinosus and quadriceps tendons. Erickson et al reported that MPFLR using autologous tendons alone significantly improved outcome scores and had a low incidence of recurrent dislocation/instability, regardless of anatomical factors. In a study with an average follow-up of 12.3 years, Shatrov et al found that MPFLR using autologous gracilis tendon was an effective treatment for recurrent patellar dislocations, with only 30% of patients exhibiting radiographic evidence of patellofemoral arthritis (Iwano stage 1). Pedicled quadriceps tendons for MPFLR have also been demonstrated to enable children and adolescents to resume sports activities without recurrence of dislocation. Overall, the current evidence suggests that MPFLR using autologous tendons is effective and feasible, although with the potential for complications such as haematomas, pain, delayed recovery and infection at the tendon harvest site. Shah et al reported a complication rate of 26.1% in a systematic review of MPFLR, while Jackson et al found an overall complication rate of 0%–32.3% with MPFLR using autologous tendons, including wound issues, persistent pain, patellar fractures and failure. Walsh et al noted that gracilis, semitendinosus and quadriceps grafts have ultimate loads of 206.2 N, 102.8 N and 190.0–205.0 N, respectively, indicating the possibility of stress failure. As an alternative solution to these challenges, MPFLR using synthetic materials could be considered. Artificial synthetic materials can reduce the issues associated with tendon harvesting and meet the load-bearing requirements of autologous tendons. Since Ellera Gomes first used polyester ligaments for MPFLR in 1992, research on synthetic materials for MPFLR has been ongoing. Lee et al reported in a prospective study that the use of FiberTape (a braided jacket of polyester tape) for MPFLR was safe and effective, significantly improving postoperative outcome indicators, with no significant difference compared with the gracilis tendon. Subsequently, Sasaki et al used FiberTape and knotless SwiveLock anchors for MPFLR, with no recurrent patellar dislocations observed during the 2-year follow-up and significant functional score improvements. Tanos et al also reported that the use of polyethylene suture combined with medial retinaculum plication for the treatment of acute patellar dislocation in young and middle-aged patients was safe and effective, regardless of anatomical abnormalities. McNeilan et al , in a systematic review comparing autograft, allograft and artificial synthetic materials, found that MPFLR alone with any graft type provided significant symptom relief. Tanos et al , in a systematic review of synthetic materials for MPFLR, also found that synthetic materials significantly improved postoperative functional outcomes without reporting serious adverse events. While the use of synthetic materials for MPFLR is currently effective and feasible, there is a lack of high-quality studies comparing the clinical outcomes of synthetic materials with autologous tendons. This study hypothesises that there will be no significant difference in postoperative outcomes between MPFLR performed with FiberWire and autologous tendons, and the former may reduce postoperative knee pain in patients. 

Study purpose This study is a single-centre, prospective, single-blind, randomised controlled clinical trial. This study aimed to verify the safety, efficacy and medium-term prognosis of MPFLR using non-absorbable surgical sutures (FiberWire) in patients with patellar dislocation and to compare the relevant indicators with those of MPFLR using autologous semitendinosus tendons in order to provide guidance for joint surgeons and sports medicine practitioners in the selection of grafts for MPFLR. Participants and eligibility criteria The study will be conducted at Xiangya Hospital, Central South University, Changsha, China. Recruitment of study participants began on 15 March 2022, and the research deadline is 31 December 2024. 30 patients who planned to undergo MPFLR to treat a patellar dislocation will be enrolled in this study and allocated randomly in a 1:1 ratio to the non-absorbable surgical suture and autologous tendon groups. The patients and the investigators collecting the relevant outcome indicators, such as scales, will be blinded to the surgical procedure. Inclusion criteria Inclusion criteria included (1) at least two or more dislocations of the patella; (2) a positive clinical physical examination (eg, patellar tear test); (3) independent MPFLR proposed for patellar instability and (4) signed informed consent form ( ). Exclusion criteria Exclusion criteria incuded (1) fixed patellar dislocation and habitual patellar dislocation; (2) tibial tuberosity deviating more than 20 mm from the glide sulcus, severe high patella, abnormal glide development (Dejour’s types C and D), abnormalities of bony structures (such as abnormal lower limb force lines); (3) combined injuries to important ligaments, such as the anterior and posterior cruciate ligaments and the medial and lateral collateral ligaments of the knee and (4) known major musculoskeletal disorders or cognitive impairment. 

This study is a single-centre, prospective, single-blind, randomised controlled clinical trial. This study aimed to verify the safety, efficacy and medium-term prognosis of MPFLR using non-absorbable surgical sutures (FiberWire) in patients with patellar dislocation and to compare the relevant indicators with those of MPFLR using autologous semitendinosus tendons in order to provide guidance for joint surgeons and sports medicine practitioners in the selection of grafts for MPFLR. 

The study will be conducted at Xiangya Hospital, Central South University, Changsha, China. Recruitment of study participants began on 15 March 2022, and the research deadline is 31 December 2024. 30 patients who planned to undergo MPFLR to treat a patellar dislocation will be enrolled in this study and allocated randomly in a 1:1 ratio to the non-absorbable surgical suture and autologous tendon groups. The patients and the investigators collecting the relevant outcome indicators, such as scales, will be blinded to the surgical procedure. Inclusion criteria Inclusion criteria included (1) at least two or more dislocations of the patella; (2) a positive clinical physical examination (eg, patellar tear test); (3) independent MPFLR proposed for patellar instability and (4) signed informed consent form ( ). Exclusion criteria Exclusion criteria incuded (1) fixed patellar dislocation and habitual patellar dislocation; (2) tibial tuberosity deviating more than 20 mm from the glide sulcus, severe high patella, abnormal glide development (Dejour’s types C and D), abnormalities of bony structures (such as abnormal lower limb force lines); (3) combined injuries to important ligaments, such as the anterior and posterior cruciate ligaments and the medial and lateral collateral ligaments of the knee and (4) known major musculoskeletal disorders or cognitive impairment. 

Inclusion criteria included (1) at least two or more dislocations of the patella; (2) a positive clinical physical examination (eg, patellar tear test); (3) independent MPFLR proposed for patellar instability and (4) signed informed consent form ( ). 

Exclusion criteria incuded (1) fixed patellar dislocation and habitual patellar dislocation; (2) tibial tuberosity deviating more than 20 mm from the glide sulcus, severe high patella, abnormal glide development (Dejour’s types C and D), abnormalities of bony structures (such as abnormal lower limb force lines); (3) combined injuries to important ligaments, such as the anterior and posterior cruciate ligaments and the medial and lateral collateral ligaments of the knee and (4) known major musculoskeletal disorders or cognitive impairment. 

A total of 30 consecutive patients who meet the inclusion criteria will be randomised to the nonabsorbable surgical suture FiberWire group (trial group) or the autologous semitendinosus tendons (control group). Each subject will be followed up continuously for 1 year ( ). Surgical operations Following satisfactory anaesthesia, the patient is positioned supine and routinely disinfected and draped. A balloon tourniquet is applied with an air pressure of 45–50 kPa, and an anteromedial and anterolateral approach is initiated to the knee. Subsequently, the suprapatellar capsule, patellofemoral joint, medial sulcus, medial compartment, intercondylar fossa, lateral compartment and lateral intercondylar sulcus are sequentially explored. Any free cartilage masses are excised if encountered, and the cartilage injury is contoured using a plasma knife. Microscopic examination of the cartilage injury is then performed in its entirety using a planer and plasma knife. The lateral patellar support band is loosened with a planer and plasma knife until the lateral patellar tilt test is positive. Intraoperatively, the fixation position of the femoral graft was determined by the same physician using palpation. Trial group A 5 cm longitudinal incision is made on the anterior medial aspect of the patella, sequentially incising through the skin and subcutaneous tissue to expose the medial edge of the patella. Two 4.75 mm anchor staples with wires (Arthrex, AR-2324PSLC) are placed at the midpoint of the medial patellar edge and above it, and non-absorbable surgical sutures are secured to the medial edge of the patella. A 3 cm longitudinal incision is then created to expose the medial femoral condyle. The MPFL stop channel is created at the midpoint of the line between the tuberosity and the medial femoral condyle. The free end of the non-absorbable surgical suture (FiberWire, Arthrex, AR-7237-7/AR-7237-7T) is threaded into the femoral channel and tensioned appropriately. The knee is flexed to the correct angle, and a wire anchor nail (Arthrex, AR-2324PSLC) is employed to secure the wire to the femoral channel. On reconfirming that the graft maintains good tension and position and that the patella does not dislocate during knee flexion and extension, the wound is thoroughly irrigated with saline and aspirated, followed by layer-by-layer closure of the incision. This procedure is illustrated in . Control group A 2 cm straight incision is placed medially to the tibial tuberosity. Subsequently, the skin and subcutaneous tissues are incised, and the Sutlers’ tendon membrane is opened. The semitendinosus tendon stop is removed along with the periosteum, and the tendon is extracted using a tendon extractor. The tendon length is measured to approximately 20 cm, and the two ends are braided and set aside. A 5 cm longitudinal incision is made on the anterior medial aspect of the patella, followed by a sequential incision of the skin and subcutaneous tissue to expose the medial edge of the patella. Anchor nails with wires (Arthrex, AR-1920SF) are placed at the midpoint of the medial patellar edge and above it. The MPFL stop channel is created at the midpoint of the line between the tuberosity of the retractor muscle and the medial femoral condyle. The autologous semitendinosus tendon is secured to the medial edge of the patella, and the free end is threaded and guided into the femoral bone channel, where it is tensioned. The knee is flexed to the appropriate angle, and the tendon is secured to the femoral bone channel using absorbable screws (Smith & Nephew, BIORO-HA°, 7 mm×25 mm). After confirming that the tendon maintains good tension and proper positioning and that the patella does not dislocate during knee flexion and extension, the wound is thoroughly irrigated with saline and aspirated, followed by layer-by-layer closure of the incision. This procedure is depicted in . Patients in the trial group and control group will be followed up at five time points, namely, preoperatively and at 1 month, 3 months, 6 months and 12 months postoperatively, by completing the relevant scales and faithfully recording any adverse events during the observation period. shows an example template of recommended content for the study. Measurements Pain assessment The trial and control groups will be assessed at five time points, namely, preoperatively, 1 month, 3 months, 6 months and 1 year postoperatively, by the same researcher with a VAS score. Clinical assessment All the study subjects will complete the Kujala score, Lysholm score and IKDC score before surgery and at 1 month, 3 months, 6 months and 1 year after surgery with the guidance of a professional researcher. The Kujala score is a scale that is used to assess patellofemoral pain and dysfunction, and studies have shown that the Chinese translation of the Kujala score is very reliable. The Lysholm score is commonly used to assess knee function and surgical outcomes before and after arthroscopic surgery, but an Italian study has shown that it is equally valid and reliable for assessing the outcome of patellofemoral surgery. The IKDC score, known as the International Knee Documentation Committee Subjective Knee Evaluation Form, is used for patients with a variety of knee conditions, such as various ligament injuries (including MPFLR), meniscal injuries and patellofemoral joint pain. All three of these scores are widely used in the preoperative and postoperative evaluation of knee function in patients with patellar dislocation. Reliability of the Kujala scale, Lysholm scale and IKDC scale was assessed using Cronbach’s alpha, with reliability coefficients greater than 0.7 indicating high internal consistency. Imaging assessment All the study subjects will receive MRI examinations at two time points, namely, preoperatively and 12 months postoperatively, and their patellar tilt angles and tibial tuberosity-trochlear groove distance will be measured to determine whether there are abnormalities in the postoperative patellar position in the trial and control groups. Quality of life assessment All the subjects in the trial and control groups will complete the 12-Item Short Form Survey (SF-12) quality of life scale before and 1 month, 3 months, 6 months and 1 year after surgery with the guidance of a professional researcher. The SF-12 scale is one of the most commonly used questionnaires in the world for epidemiological characterisation studies. Statistical analysis The investigators appointed professional staff from the Department of Joint Surgery, Xiangya Hospital, Central South University, to be responsible for data collection after careful study and training on various rating scales and imaging-specific index measurements. The collected data will be analysed using SPSS V.22.0 statistical software. Categorical data are presented as absolute numbers, ratios or percentages. Continuous data are reported as the mean, mean±SD and range. The normality of the measurement variables is assessed using quantile-quantile plots and the Shapiro-Wilk test. Comparisons of normally distributed measurement outcomes between the trial groups and control groups are performed using an independent samples t-test; if the normality assumption is not met, the Mann-Whitney U test is used. Intragroup comparisons of variables before and after surgery are performed using the paired t-test and/or the paired χ 2 test. The significance level is set at α=0.05. Sample size calculation Sample size and test efficacy will be estimated using the Kujala score as the primary endpoint. The results of previous studies in which autologous tendons were used for anterior cruciate ligament reconstruction were used to define the control group, and the Kujala score increased from 56.7±17.7 (2×SD) preoperatively to 86.8±14.4 (2×SD) postoperatively. Based on a widely cited Canadian study, we defined the minimum clinically significant difference as half the SD. Using the results of a previous anterior cruciate ligament reconstruction-related study, we determined σ=7.2% in the treatment cohort, thus yielding a clinically detectable difference of 10 points. Using a 1:1 inclusion ratio, a beta coefficient of 0.2, and an alpha coefficient of 0.05, the sample size was calculated using a web-based calculator ( www.openepi.com ), requiring a total of 30 patients—15 subjects each in the trial and control groups. Patient and public involvement Patients and/or the public were not involved in the study design, conduct, reporting or dissemination plans. Analysis of safety indicators The safety evaluation will be conducted using a safety-set analysis dataset. Adverse events will be coded according to the internationally recognised Medical Dictionary for Regulatory Activities term set classification. The types of adverse events, their frequency, severity and their relationship with different grafts will be summarised for each group. A comprehensive list of adverse events will be provided, with specific notes for participants who discontinued the trial due to adverse events and those who experienced serious adverse events. The χ 2 test will be used to compare the proportions of patients who developed complications between treatment groups. 

Following satisfactory anaesthesia, the patient is positioned supine and routinely disinfected and draped. A balloon tourniquet is applied with an air pressure of 45–50 kPa, and an anteromedial and anterolateral approach is initiated to the knee. Subsequently, the suprapatellar capsule, patellofemoral joint, medial sulcus, medial compartment, intercondylar fossa, lateral compartment and lateral intercondylar sulcus are sequentially explored. Any free cartilage masses are excised if encountered, and the cartilage injury is contoured using a plasma knife. Microscopic examination of the cartilage injury is then performed in its entirety using a planer and plasma knife. The lateral patellar support band is loosened with a planer and plasma knife until the lateral patellar tilt test is positive. Intraoperatively, the fixation position of the femoral graft was determined by the same physician using palpation. Trial group A 5 cm longitudinal incision is made on the anterior medial aspect of the patella, sequentially incising through the skin and subcutaneous tissue to expose the medial edge of the patella. Two 4.75 mm anchor staples with wires (Arthrex, AR-2324PSLC) are placed at the midpoint of the medial patellar edge and above it, and non-absorbable surgical sutures are secured to the medial edge of the patella. A 3 cm longitudinal incision is then created to expose the medial femoral condyle. The MPFL stop channel is created at the midpoint of the line between the tuberosity and the medial femoral condyle. The free end of the non-absorbable surgical suture (FiberWire, Arthrex, AR-7237-7/AR-7237-7T) is threaded into the femoral channel and tensioned appropriately. The knee is flexed to the correct angle, and a wire anchor nail (Arthrex, AR-2324PSLC) is employed to secure the wire to the femoral channel. On reconfirming that the graft maintains good tension and position and that the patella does not dislocate during knee flexion and extension, the wound is thoroughly irrigated with saline and aspirated, followed by layer-by-layer closure of the incision. This procedure is illustrated in . Control group A 2 cm straight incision is placed medially to the tibial tuberosity. Subsequently, the skin and subcutaneous tissues are incised, and the Sutlers’ tendon membrane is opened. The semitendinosus tendon stop is removed along with the periosteum, and the tendon is extracted using a tendon extractor. The tendon length is measured to approximately 20 cm, and the two ends are braided and set aside. A 5 cm longitudinal incision is made on the anterior medial aspect of the patella, followed by a sequential incision of the skin and subcutaneous tissue to expose the medial edge of the patella. Anchor nails with wires (Arthrex, AR-1920SF) are placed at the midpoint of the medial patellar edge and above it. The MPFL stop channel is created at the midpoint of the line between the tuberosity of the retractor muscle and the medial femoral condyle. The autologous semitendinosus tendon is secured to the medial edge of the patella, and the free end is threaded and guided into the femoral bone channel, where it is tensioned. The knee is flexed to the appropriate angle, and the tendon is secured to the femoral bone channel using absorbable screws (Smith & Nephew, BIORO-HA°, 7 mm×25 mm). After confirming that the tendon maintains good tension and proper positioning and that the patella does not dislocate during knee flexion and extension, the wound is thoroughly irrigated with saline and aspirated, followed by layer-by-layer closure of the incision. This procedure is depicted in . Patients in the trial group and control group will be followed up at five time points, namely, preoperatively and at 1 month, 3 months, 6 months and 12 months postoperatively, by completing the relevant scales and faithfully recording any adverse events during the observation period. shows an example template of recommended content for the study. 

A 5 cm longitudinal incision is made on the anterior medial aspect of the patella, sequentially incising through the skin and subcutaneous tissue to expose the medial edge of the patella. Two 4.75 mm anchor staples with wires (Arthrex, AR-2324PSLC) are placed at the midpoint of the medial patellar edge and above it, and non-absorbable surgical sutures are secured to the medial edge of the patella. A 3 cm longitudinal incision is then created to expose the medial femoral condyle. The MPFL stop channel is created at the midpoint of the line between the tuberosity and the medial femoral condyle. The free end of the non-absorbable surgical suture (FiberWire, Arthrex, AR-7237-7/AR-7237-7T) is threaded into the femoral channel and tensioned appropriately. The knee is flexed to the correct angle, and a wire anchor nail (Arthrex, AR-2324PSLC) is employed to secure the wire to the femoral channel. On reconfirming that the graft maintains good tension and position and that the patella does not dislocate during knee flexion and extension, the wound is thoroughly irrigated with saline and aspirated, followed by layer-by-layer closure of the incision. This procedure is illustrated in . 

A 2 cm straight incision is placed medially to the tibial tuberosity. Subsequently, the skin and subcutaneous tissues are incised, and the Sutlers’ tendon membrane is opened. The semitendinosus tendon stop is removed along with the periosteum, and the tendon is extracted using a tendon extractor. The tendon length is measured to approximately 20 cm, and the two ends are braided and set aside. A 5 cm longitudinal incision is made on the anterior medial aspect of the patella, followed by a sequential incision of the skin and subcutaneous tissue to expose the medial edge of the patella. Anchor nails with wires (Arthrex, AR-1920SF) are placed at the midpoint of the medial patellar edge and above it. The MPFL stop channel is created at the midpoint of the line between the tuberosity of the retractor muscle and the medial femoral condyle. The autologous semitendinosus tendon is secured to the medial edge of the patella, and the free end is threaded and guided into the femoral bone channel, where it is tensioned. The knee is flexed to the appropriate angle, and the tendon is secured to the femoral bone channel using absorbable screws (Smith & Nephew, BIORO-HA°, 7 mm×25 mm). After confirming that the tendon maintains good tension and proper positioning and that the patella does not dislocate during knee flexion and extension, the wound is thoroughly irrigated with saline and aspirated, followed by layer-by-layer closure of the incision. This procedure is depicted in . Patients in the trial group and control group will be followed up at five time points, namely, preoperatively and at 1 month, 3 months, 6 months and 12 months postoperatively, by completing the relevant scales and faithfully recording any adverse events during the observation period. shows an example template of recommended content for the study. 

Pain assessment The trial and control groups will be assessed at five time points, namely, preoperatively, 1 month, 3 months, 6 months and 1 year postoperatively, by the same researcher with a VAS score. Clinical assessment All the study subjects will complete the Kujala score, Lysholm score and IKDC score before surgery and at 1 month, 3 months, 6 months and 1 year after surgery with the guidance of a professional researcher. The Kujala score is a scale that is used to assess patellofemoral pain and dysfunction, and studies have shown that the Chinese translation of the Kujala score is very reliable. The Lysholm score is commonly used to assess knee function and surgical outcomes before and after arthroscopic surgery, but an Italian study has shown that it is equally valid and reliable for assessing the outcome of patellofemoral surgery. The IKDC score, known as the International Knee Documentation Committee Subjective Knee Evaluation Form, is used for patients with a variety of knee conditions, such as various ligament injuries (including MPFLR), meniscal injuries and patellofemoral joint pain. All three of these scores are widely used in the preoperative and postoperative evaluation of knee function in patients with patellar dislocation. Reliability of the Kujala scale, Lysholm scale and IKDC scale was assessed using Cronbach’s alpha, with reliability coefficients greater than 0.7 indicating high internal consistency. Imaging assessment All the study subjects will receive MRI examinations at two time points, namely, preoperatively and 12 months postoperatively, and their patellar tilt angles and tibial tuberosity-trochlear groove distance will be measured to determine whether there are abnormalities in the postoperative patellar position in the trial and control groups. Quality of life assessment All the subjects in the trial and control groups will complete the 12-Item Short Form Survey (SF-12) quality of life scale before and 1 month, 3 months, 6 months and 1 year after surgery with the guidance of a professional researcher. The SF-12 scale is one of the most commonly used questionnaires in the world for epidemiological characterisation studies. 

The trial and control groups will be assessed at five time points, namely, preoperatively, 1 month, 3 months, 6 months and 1 year postoperatively, by the same researcher with a VAS score. 

All the study subjects will complete the Kujala score, Lysholm score and IKDC score before surgery and at 1 month, 3 months, 6 months and 1 year after surgery with the guidance of a professional researcher. The Kujala score is a scale that is used to assess patellofemoral pain and dysfunction, and studies have shown that the Chinese translation of the Kujala score is very reliable. The Lysholm score is commonly used to assess knee function and surgical outcomes before and after arthroscopic surgery, but an Italian study has shown that it is equally valid and reliable for assessing the outcome of patellofemoral surgery. The IKDC score, known as the International Knee Documentation Committee Subjective Knee Evaluation Form, is used for patients with a variety of knee conditions, such as various ligament injuries (including MPFLR), meniscal injuries and patellofemoral joint pain. All three of these scores are widely used in the preoperative and postoperative evaluation of knee function in patients with patellar dislocation. Reliability of the Kujala scale, Lysholm scale and IKDC scale was assessed using Cronbach’s alpha, with reliability coefficients greater than 0.7 indicating high internal consistency. 

All the study subjects will receive MRI examinations at two time points, namely, preoperatively and 12 months postoperatively, and their patellar tilt angles and tibial tuberosity-trochlear groove distance will be measured to determine whether there are abnormalities in the postoperative patellar position in the trial and control groups. 

All the subjects in the trial and control groups will complete the 12-Item Short Form Survey (SF-12) quality of life scale before and 1 month, 3 months, 6 months and 1 year after surgery with the guidance of a professional researcher. The SF-12 scale is one of the most commonly used questionnaires in the world for epidemiological characterisation studies. 

The investigators appointed professional staff from the Department of Joint Surgery, Xiangya Hospital, Central South University, to be responsible for data collection after careful study and training on various rating scales and imaging-specific index measurements. The collected data will be analysed using SPSS V.22.0 statistical software. Categorical data are presented as absolute numbers, ratios or percentages. Continuous data are reported as the mean, mean±SD and range. The normality of the measurement variables is assessed using quantile-quantile plots and the Shapiro-Wilk test. Comparisons of normally distributed measurement outcomes between the trial groups and control groups are performed using an independent samples t-test; if the normality assumption is not met, the Mann-Whitney U test is used. Intragroup comparisons of variables before and after surgery are performed using the paired t-test and/or the paired χ 2 test. The significance level is set at α=0.05. 

Sample size and test efficacy will be estimated using the Kujala score as the primary endpoint. The results of previous studies in which autologous tendons were used for anterior cruciate ligament reconstruction were used to define the control group, and the Kujala score increased from 56.7±17.7 (2×SD) preoperatively to 86.8±14.4 (2×SD) postoperatively. Based on a widely cited Canadian study, we defined the minimum clinically significant difference as half the SD. Using the results of a previous anterior cruciate ligament reconstruction-related study, we determined σ=7.2% in the treatment cohort, thus yielding a clinically detectable difference of 10 points. Using a 1:1 inclusion ratio, a beta coefficient of 0.2, and an alpha coefficient of 0.05, the sample size was calculated using a web-based calculator ( www.openepi.com ), requiring a total of 30 patients—15 subjects each in the trial and control groups. 

Patients and/or the public were not involved in the study design, conduct, reporting or dissemination plans. 

The safety evaluation will be conducted using a safety-set analysis dataset. Adverse events will be coded according to the internationally recognised Medical Dictionary for Regulatory Activities term set classification. The types of adverse events, their frequency, severity and their relationship with different grafts will be summarised for each group. A comprehensive list of adverse events will be provided, with specific notes for participants who discontinued the trial due to adverse events and those who experienced serious adverse events. The χ 2 test will be used to compare the proportions of patients who developed complications between treatment groups. 

The present study is a single-blind, randomised controlled trial designed to examine the clinical outcomes of MPFLR using artificial synthetic materials (FiberWire) versus autologous semitendinosus tendons. A 1-year follow-up period was employed to compare the subjective and objective outcomes between the FiberWire and semitendinosus tendon groups. This study hypothesises that MPFLR with FiberWire will not yield a significant difference in postoperative outcomes compared with the use of semitendinosus tendons and that FiberWire may mitigate postoperative knee pain in patients. The use of artificial synthetic materials in MPFLR has a history of nearly three decades. Ellera Gomes initiated the use of polyester ligaments for MPFLR, with an average follow-up of 39 months, demonstrating significant improvement in symptoms in 83% of patients. The synthetic materials have since evolved from polyester to ultra-high molecular weight substances such as FiberTape and FiberWire, which are composed of ultra-high molecular weight polyethylene, polyester and nylon. Commercial products like Poly-Tape PT20 (Neoligaments, Leeds, UK), Leeds-Keio (Neoligaments, Leeds, UK) and FiberTape (Arthrex, Florida, USA) are available, and sizes can be customised to suit individual needs. A range of case series studies employing artificial synthetic materials have demonstrated significant improvements in clinical symptoms without the occurrence of severe complications. Furthermore, there are comparative studies between artificial synthetic materials and autologous tendons. Lee et al reported that the functional knee scores achieved with FiberTape for MPFLR were not significantly different from those with gracilis tendon, and no serious complications were noted. Milinkovic et al found that the clinical outcomes of MPFLR with FiberTape, in conjunction with lateral patellar instability (LPI) correction procedure, were comparable to those with quadriceps tendon, with clinical improvements exceeding the minimum clinically important difference. At the final follow-up, 2 years postprocedure, there was no significant difference in patellofemoral joint pain and functional improvement between the two groups, and no serious complications were reported. Noteworthily, Lee et al ’s investigation, which involved the use of FiberTape for MPFLR in patients devoid of anatomical risk factors for LPI, yielded outcomes that were commensurate with those achieved through autograft reconstruction. Conversely, Milinkovic et al implemented FiberTape for MPFLR concurrently with tibial tuberosity osteotomy, trochleoplasty or distal femoral osteotomy to rectify the anatomical factors contributing to LPI, yet still achieved comparable results. It must be acknowledged that these two studies do not provide strong evidence that artificial synthetic materials can produce results similar to those of autografts in MPFLR. Several factors contribute to the observed outcomes, including the diversity of artificial synthetic materials in terms of their types and specifications, the variability in the selection of autologous tendons, and the implementation of either a single-bundle or double-bundle technique for MPFLR. Moreover, patellar dislocation is frequently encountered in paediatric and adolescent patients with open growth plates, underscoring the importance of method selection that is meticulously tailored to the individual patient’s circumstances. In conclusion, the potential utility of artificial synthetic materials in MPFLR is substantial, although lacking robust clinical evidence to support their routine application. Therefore, in this randomised controlled trial, we will prospectively compare the short-term clinical outcomes of MPFLR using artificial synthetic materials versus autologous tendons to elucidate the clinical value of artificial synthetic materials in MPFLR. Ethics and dissemination The trial was approved by the Medical Ethics Committee of Xiangya Hospital of Central South University on 26 October 2021 (ethics number: 202110478) and registered in the China Clinical Trials Registry on 15 March 2022 (registration number: ChiCTR2200057574). All the study participants will be fully informed about the study and sign an informed consent form before enrolment. Patients are permitted to withdraw from the study at their discretion at any point during the trial, without facing discrimination or any form of retribution. Their medical treatment and rights will remain unaffected. The investigator is responsible for voluntarily withdrawing the subject from the clinical trial under the following circumstances: (1) if the subject experiences a significant decline in knee function and continued participation would be detrimental to their treatment without proper management; (2) if the subject demonstrates poor compliance and is unable to adhere to the clinical trial protocol regarding study interventions, regular reviews and follow-up; (3) if the subject experiences serious adverse events related to the study intervention and (4) in the event of other circumstances that may pose an increased risk to the subject or compromise the reliability of the study outcomes. Any serious adverse events must be reported to the study director and ethics committee within 12 hours. It is crucial to note that all data collected up to the point of withdrawal will be retained as part of the trial data for subsequent statistical analysis and will not be disregarded or discarded. All investigators will keep the study results confidential until after the data are made public and will release no data related to the database without approval from the principal investigator. We will publish our findings and data in peer-reviewed journals and present them at national and international conferences. 

The trial was approved by the Medical Ethics Committee of Xiangya Hospital of Central South University on 26 October 2021 (ethics number: 202110478) and registered in the China Clinical Trials Registry on 15 March 2022 (registration number: ChiCTR2200057574). All the study participants will be fully informed about the study and sign an informed consent form before enrolment. Patients are permitted to withdraw from the study at their discretion at any point during the trial, without facing discrimination or any form of retribution. Their medical treatment and rights will remain unaffected. The investigator is responsible for voluntarily withdrawing the subject from the clinical trial under the following circumstances: (1) if the subject experiences a significant decline in knee function and continued participation would be detrimental to their treatment without proper management; (2) if the subject demonstrates poor compliance and is unable to adhere to the clinical trial protocol regarding study interventions, regular reviews and follow-up; (3) if the subject experiences serious adverse events related to the study intervention and (4) in the event of other circumstances that may pose an increased risk to the subject or compromise the reliability of the study outcomes. Any serious adverse events must be reported to the study director and ethics committee within 12 hours. It is crucial to note that all data collected up to the point of withdrawal will be retained as part of the trial data for subsequent statistical analysis and will not be disregarded or discarded. All investigators will keep the study results confidential until after the data are made public and will release no data related to the database without approval from the principal investigator. We will publish our findings and data in peer-reviewed journals and present them at national and international conferences. 

10.1136/bmjopen-2024-084187 online supplemental file 1 

