Anatomical transverse patella double tunnel reconstruction of medial patellofemoral ligament with a hamstring tendon autograft for recurrent patellar dislocation

Stiffness and Instability After MPFL Reconstruction Using a Fluoroscopic Versus Open Technique to Localize the Femoral Attachment Site: A Systematic Review and Meta-analysis

Background

Open and fluoroscopic techniques have been described for localization of the femoral attachment site in medial patellofemoral ligament (MPFL) reconstruction. No study to date has evaluated if one technique is superior to another in terms of complications.

Purpose

To review the literature comparing clinical outcomes of MPFL reconstruction using the fluoroscopic versus open technique to localize the site of femoral graft placement.

Study Design

Systematic review; Level of evidence, 4.

Methods

A systematic literature review was performed via PubMed, Embase, and CINAHL to identify articles published between the inception of these databases and March 1, 2022, in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. This search yielded 4183 publications for initial review. Studies with at least a 2-year follow-up and complete reporting of patient-reported outcomes, range of motion, recurrent instability, and/or complications (ie, stiffness, infection, persistent pain) were included. We excluded studies of patients with collagen disorders; revision surgeries; surgeries with concomitant procedures; synthetic MPFL reconstruction; MPFL repairs; combined open and radiographic technique; and case series that included <10 patients. A proportional meta-analysis was performed by calculating the pooled estimate of incidence with 95% CIs using a fixed-effects model with double arcsine transformation (Freeman-Tukey) for each type of surgical technique (fluoroscopic or open).

Results

A total of 29 studies met our inclusion criteria, of which 15 studies (566 patients) used the open technique and 14 studies (620 patients) used fluoroscopy. There were no significant differences between the open and fluoroscopic techniques in the incidence of postoperative apprehension (P = .4826), postoperative subjective instability (P = .1095), postoperative objective instability (P = .5583), reoperations (P = .7981), recurrent dislocation (P = .6690), or arthrofibrosis (P = .8118).

Conclusion

Both open and radiographic localization of the femoral graft position in MPFL reconstruction offer similar outcomes and rates of complications.

Comparison of Clinical and Radiological Results of Lateral Retinacular Release or Lateral Retinacular Lengthening Methods Combined With Medial Retinaculum Plication in Patellofemoral Instability

Introduction

In this study, we aimed to compare the clinical and radiological results of patients who underwent medial retinaculum plication (MRP) combined with lateral retinacular release (LRR) or lateral retinacular lengthening (LRL) with the diagnosis of patellofemoral (PF) instability.

Methods

In our study, we retrospectively analyzed 75 knees of 75 adult patients (43 females and 32 males) who underwent MRP+LRR or MRP+LRL due to PF instability without osseous pathologies. Patients were divided into two groups (MRP+LRR and MRP+LRL) according to the surgical method. The clinical and radiological results of the two groups were compared.

Results

MRP+LRL surgery was performed on 45 knees and MRP+LRR surgery on 30 knees. The mean age was 26.5 (18-43) years. There was no significant difference between the two groups in the change in patellar lateral shift (PLS) (p=0.429) and congruence angle (CA) (p=0.218) values. However, there was a significant difference between the two groups in the change in patellar tilt angle (PTA) (p=0.009) and lateral patellofemoral angle (LPFA) (p<0.001) values. The change in PTA and LPFA values was higher in the MRP+LRL group. There was no significant difference between the two groups in terms of pre-operative and post-operative Lysholm knee scoring scale (p=0.205, p=0.228), Kujala pain scale (p=0.393, p=0.596), and Tegner activity level scale values (p=0.121, p=0.899).

Conclusions

MRP+LRR or MRP+LRL provided successful results for correcting the instability in PF instability without osseous pathologies such as patella alta, tibial tubercle-trochlear groove (TT-TG) dysplasia, trochlea dysplasia, genu valgus, and tibial-femoral torsion. While PTA and LPFA values improved more with the MRP-LRL method, clinical results were similar in both methods.

Protocols of rehabilitation and return to sport, and clinical outcomes after medial patellofemoral ligament reconstruction with and without tibial tuberosity osteotomy: a systematic review

PURPOSE

No consensus exists on rehabilitation programmes after medial patellofemoral ligament reconstruction (MPFLR) with or without tibial tuberosity osteotomy (TTO). This systematic review examined the content and timeline of rehabilitation (weightbearing, range of motion [ROM] and exercise therapy) and return to sport (RTS), as well as patient-reported outcomes after MPFLR with or without TTO.

METHODS

The PubMed, Cochrane Library, Web of Sciences, CINAHL and SPORTDiscus databases were searched from inception to December 2021. Studies that reported postoperative rehabilitation programmes and patient-reported outcomes for patients aged ≥ 18 years who underwent MPFLR with or without concomitant TTO were included.

RESULTS

Eighty-five studies were included, 57 of which were case series and only one randomised controlled trial on rehabilitation programmes. Non-weightbearing was set within one week post-operatively in approximately 80% of weightbearing programmes for MPFLR without and with TTO. Joint immobilisation was set within one week post-operatively in 65.3% and 93.8% of programmes for MPFLR without and with TTO, respectively. Weightbearing and ROM (≤ 90°) restriction were within three weeks post-operatively for > 50% of the programmes. Quadriceps strengthening was the most cited exercise therapy (33 programmes), most often initiated within two weeks post-operatively. However, few other exercise programmes were cited (only nine programmes). RTS was mostly noted at six months post-operatively (35 programmes). The weighted mean Kujala score was 87.4 points.

CONCLUSION

Regardless of TTO addition to MPFLR, most studies restricted weightbearing and ROM only in the early post-operative period, with seemingly favourable clinical results. Limited information was available on post-operative exercise therapy.

Influence of the Fluoroscopy Setting towards the Patient When Identifying the MPFL Insertion Point

(1) The malposition of the femoral tunnel in medial patellofemoral ligament (MPFL) reconstruction can lead to length changes in the MPFL graft, and an increase in medial peak pressure in the patellofemoral joint. It is the cause of 36% of all MPFL revisions. According to Schöttle et al., the creation of the drill canal should be performed in a strictly lateral radiograph. In this study, it was hypothesized that positioning the image receptor to the knee during intraoperative fluoroscopy would lead to a relevant mispositioning of the femoral tunnel, despite an always adjusted true-lateral view. (2) A total of 10 distal femurs were created from 10 knee CT scans using a 3D printer. First, true-lateral fluoroscopies were taken from lateral to medial at a 25 cm (LM25) distance from the image receptor, then from medial to lateral at a 5 cm (ML5) distance. Using the method from Schöttle, the femoral origin of the MPFL was determined when the femur was positioned distally, proximally, superiorly, and inferiorly to the image receptor. (3) The comparison of the selected MPFL insertion points according to Schöttle et al. revealed that the initial determination of the point in the ML5 view resulted in a distal and posterior shift of the point by 5.3 mm ± 1.2 mm when the point was checked in the LM25 view. In the opposite case, when the MPFL insertion was initially determined in the LM25 view and then redetermined in the ML5 view, there was a shift of 4.8 mm ± 2.2 mm anteriorly and proximally. The further positioning of the femur (distal, proximal, superior, and inferior) showed no relevant influence. (4) For fluoroscopic identification of the femoral MPFL, according to Schöttle et al., attention should be paid to the position of the fluoroscopy in addition to a true-lateral view.

Lateral release associated with MPFL reconstruction in patients with acute patellar dislocation

Objective

Medial patellofemoral ligament (MPFL) injury occurs in the majority of the cases of acute patellar dislocation. The role of concomitant lateral retinaculum release with MPFL reconstruction is not clearly understood. Even though the lateral retinaculum plays a role in both medial and lateral patellofemoral joint stability in MPFL intact knees, studies have shown mixed clinical outcomes following its release during MPFL reconstruction surgery. Better understanding of the biomechanical effects of the release of the lateral retinaculum during MPFL reconstruction is warranted. We hypothesize that performing a lateral release concurrent with MPFL reconstruction will disrupt the patellofemoral joint biomechanics and result in lateral patellar instability.

Methods

A previously developed and validated finite element (FE) model of the patellofemoral joint was used to understand the effect of lateral retinaculum release following MPFL reconstruction. Contact pressure (CP), contact area (CA) and lateral patellar displacement were recorded. abstract.

Results

FE modeling and analysis demonstrated that lateral retinacular release following MPFL reconstruction with tibial tuberosity-tibial groove distance (TT-TG) of 12 mm resulted in a 39% decrease in CP, 44% decrease in CA and a 20% increase in lateral patellar displacement when compared to a knee with an intact MPFL. In addition, there was a 45% decrease in CP, 44% decrease in CA and a 21% increase in lateral displacement when compared to a knee that only had an MPFL reconstruction.

Conclusion

This FE-based analysis exhibits that concomitant lateral retinaculum release with MPFL reconstruction results in decreased PF CA, CP and increased lateral patellar displacement with increased knee flexion, which may increase the risk of patellar instability.

Comparing Nonoperative Treatment, MPFL Repair, and MPFL Reconstruction for Patients With Patellar Dislocation: A Systematic Review and Network Meta-analysis

Background:

Medial patellofemoral ligament (MPFL) reconstruction, MPFL repair, and nonoperative treatment are important treatments for patients with patellar dislocation. However, it is unclear which treatment leads to better outcomes.

Purpose:

To determine the efficacy and safety of the 3 treatments in the treatment of patellar dislocation and compare the effect of MPFL reconstruction with MPFL repair, MPFL reconstruction with nonoperative treatment, and MPFL repair with nonoperative treatment.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

The PubMed, Web of Science, Cochrane Library, Embase, CNKI (China National Knowledge Infrastructure), and Wanfang databases were searched from inception to December 2020. Included were clinical studies that described the efficacy and safety of 2 of the 3 treatments, studies directly comparing the clinical effects of the 2 operative techniques, or studies comparing the effects of reconstruction or repair with nonoperative treatment. Two reviewers independently extracted data and assessed the quality of the included studies with the Cochrane risk-of-bias tools. The outcomes evaluated were postoperative redislocation rate, revision rate, complications, and Kujala score. We used traditional direct pairwise meta-analysis as well as network meta-analysis for comprehensive efficacy of all 3 treatment measures.

Results:

Twelve studies were included: 5 compared MPFL reconstruction with MPFL repair, 2 compared MPFL reconstruction with nonoperative treatment, and 5 compared MPFL repair with nonoperative treatment. The risk of bias was serious in 4, moderate in 4 and low in 4 articles. MPFL reconstruction led to significantly reduced redislocation and improved Kujala scores compared with MPFL repair and nonoperative treatment. MPFL repair led to reduced redislocation rates compared with nonoperative treatment but did not show an obvious benefit in primary dislocations. There was no significant difference among the 3 treatments in terms of revision rate and incidence of complications, although we found that treatment-related complications were least likely to occur in nonoperative treatment.

Conclusion:

The results of this review indicate that MPFL reconstruction decreases recurrent dislocation compared with MPFL repair or nonoperative treatment, but it has a higher possibility of complications. MPFL repair resulted in less postoperative redislocation than nonoperative treatment but did not show an obvious benefit in primary dislocation.

Prognostic factors for isolated medial patellofemoral ligament reconstruction: A systematic review

BACKGROUND

Evidence concerning the influence gender, age, and the time elapsed from the first dislocation to surgery in the outcomes of Medial Patella Femoral Ligament (MPFL) reconstruction are lacking. This systematic review was conducted to investigate whether patient characteristics have an influence in the clinical outcomes of MPFL reconstruction for patients with patellofemoral instability.

MATERIAL AND METHODS

This study followed the PRISMA guidelines. The main databases were accessed in February 2021. All the studies reporting outcomes of primary MPFL reconstruction in patients with recurrent patellofemoral instability were considered for inclusion. A multivariate analysis diagnostic tool was used to analyse the association between age, gender and time from injury to surgery and the surgical outcomes at last follow-up.

RESULTS

A total of 50 articles (2037 procedures) were included. The mean follow-up was 40.90 ± 24.8 months. The mean age was 23.6 ± 3.9 years. 64.3% (1309 of 2037 patients) were female. The mean time from injury to surgery was 64.5 ± 48.9 months. Women showed no statistically significant association with the Kujala score or complications. Older patients had a reduced risk to incur re-dislocations (P = 0.01) and revisions (P = 0.01). Longer time from injury to surgery was associated with greater risk to incur re-dislocations (P = 0.01), and with lower Kujala score (P < 0.0001). No other statistically significant association was evidenced.

CONCLUSION

The time span from the first patellar dislocation to the surgical reconstruction was a negative prognostic factor, while sex had no influence on surgical outcomes. The role of patients age on surgical outcomes remains unclear.

A computed tomography cadaveric study of the radiological anatomy of the patella: the size of the patella correlates with bone bridge between tunnels and R angles are introduced for safe tunnel drilling during MPFL reconstruction

PURPOSE

To measure the safe range of angles during tunnel drilling and map ideal patella tunnel placement with the use of preoperative computed tomography (CT) scan and compare results after medial patellofemoral ligament (MPFL) reconstruction using a hardware-free patellar fixation technique with two semi-patellar tunnels between a) a free-hand technique, and b) its modification with the use of an anterior cruciate ligament (ACL) tibia aiming device.

METHODS

CT scan was performed on 30 fresh-frozen cadaveric knees a) prior to any intervention and b) after MPFL reconstruction. For MPFL reconstruction, specimens were randomly allocated to 1) Group A, which consisted of knees operated with free-hand, hardware-free patellar fixation technique with two semi-patellar tunnels and 2) Group B, which consisted of knees operated on with a technique modification with the ACL tibia device.

PATELLAR MEASUREMENTS

L1 was the maximal patellar length. L2 was the minimum possible distance of placement for the upper tunnel from the proximal pole of the patella. The maximum bone bridge between tunnels was calculated as half of L1 minus the L2 distance (L1/2-L2). We also measured R1 and R2 angles at the proximal and distal tunnel that represent safe angles at the entry point during tunnel drilling (without breaching the anterior cortex or articular cartilage).

RESULTS

Preoperatively, mean L1 was 3.45 cm (range 3.05-4.52). Mean L2 was 0.62 cm (range 0.49-0.89). The mean maximum possible bone bridge between tunnels (L1/2-L2) was 1.1 cm (range 0.77-1.58). R1 was 6.05⁰ (range 4.78-7.44), R2 was 6.64⁰ (range 4.57-9.03), and their difference reached statistical significance (p = 0.03). Postoperatively, in group A, in 4 out of 15 patellas, multiple attempts were made during tunnel drilling in order to avoid anterior cortex or cartilage breaching. In group B, all tunnels were correctly drilled with the first attempt. Bone bridge between tunnels was significantly shorter postoperatively (0.93 cm, p < 0.01).

CONCLUSION

Small-size patellae correlate with short maximum bone bridge between tunnels, which makes anatomic, double-bundle, hardware-free patella fixation, with two semi-patellar tunnels MPFL reconstruction challenging. Furthermore, R angles create a narrow window to avoid intraoperative breaching, rendering the use of the ACL tibia device an extremely useful instrument.

LEVEL OF EVIDENCE

II.

Isolated medial patellofemoral ligament reconstruction for recurrent patellofemoral instability: analysis of outcomes and risk factors

Background

The medial patellofemoral ligament (MPFL) is always damaged after patellar dislocation. In selected patients, MPFL reconstruction is necessary to restore a correct patellar tracking. Despite the large number of different techniques reported to reconstruct the MPFL, there is no consensus concerning the optimal procedure, and debates is still ongoing. The present study analysed the results after isolated MPFL reconstruction in patients with patellofemoral instability. Furthermore, a subgroup analysis of patients presenting pathoanatomical risk factors was made.

Methods

In November 2020, the main electronic databases were accessed. All articles reporting the results of primary isolated MPFL reconstruction for recurrent patellofemoral instability were considered for inclusion. Only articles reporting a minimum 12-month follow-up were eligible.

Results

Data from a total of 1777 knees were collected. The mean age of the patients involved was 22.8 ± 3.4 years. The mean follow-up was 40.7 ± 25.8 months. Overall, the range of motion (+ 27.74; P < 0.0001) and all the other scores of interests improved at last follow-up: Kujala (+ 12.76; P = 0.0003), Lysholm (+ 15.69; P < 0.0001), Tegner score (+ 2.86; P = 0.006). Seventy-three of 1780 patients (4.1%) showed a positive apprehension test. Thirty of 1765 patients (1.7%) experienced re-dislocations, while 56 of 1778 patients (3.2%) showed persisting joint instability. Twenty-five of 1786 patients (1.4%) underwent revision surgeries.

Conclusion

Isolated MPFL reconstruction for recurrent patellofemoral instability provides reliable surgical outcomes. Patients with pathoanatomical predisposing factors reported worse surgical outcomes.

Lateral retinacular release combined with MPFL reconstruction for patellofemoral instability: a systematic review

INTRODUCTION

The role of the lateral retinaculum in patellofemoral instability is still debated. Lateral retinacular release (LRR), has been extensively performed in combination with different surgical procedures, including reconstruction of medio-patellofemoral ligament (MPFL). Despite controversial indications, the results from these studies seem promising. The present study conducts a systematic review about current biomechanical and clinical evidence concerning the role of LRR in combination with MPFL reconstruction. We performed a comprehensive literature research, comparing the outcomes of MPFL reconstruction with and without LRR.

MATERIALS AND METHODS

This systematic review was conducted according to the PRISMA guidelines. The literature search was performed in August 2020. All articles describing the outcome of isolated MPFL reconstruction alone or in combination with a LRR in patients with recurrent patellofemoral instability were considered for inclusion. Only articles reporting data on patients with a minimum of 12-month follow-up were included. Only articles reporting quantitative data under the outcomes of interest were included.

RESULTS

A total of 63 articles were eligible for this systematic review, including 2131 knees. The mean follow-up was 40.87 ± 24.1 months. All scores of interests improved in favour of the combined group: Kujala + 3.8% (P = 0.01), Lysholm + 4.2% (P = 0.004), Tegner + 0.8 points (P = 0.04), IKDC + 9.8% (P = 0.02). The ROM was comparable between the two groups (P = 0.4). Similarity was found in terms of positivity to the apprehension test (P = 0.05), rate of complications (P = 0.1), re-dislocations (P = 0.8), and revision surgeries (P = 0.1).

CONCLUSION

There is no evidence that adding a lateral release impacts positively on the outcome of MPFL reconstruction.

LEVEL OF EVIDENCE

IV, Systematic review.

Patellofemoral Contact Pressure for Medial Patellofemoral Ligament Reconstruction Using Suture Tape Varies With the Knee Flexion Angle: A Biomechanical Evaluation

PURPOSE

The purpose of this study was to evaluate the effect of the knee flexion angle during graft fixation on patellofemoral (PF) contact pressure in medial patellofemoral ligament (MPFL) reconstruction using polyester suture tape and knotless anchors.

METHODS

Nine human knees (mean age 74.9 ± 14.1 years) were used in this study. Polyester suture tape was fixed at the medial edge of the patella with two 3.5-mm knotless anchors, and then to the femur with a 4.75-mm knotless anchor at 4 different knee flexion angles (0°, 30°, 60°, and 90°). A pressure sensor was used to measure the maximum contact pressure (MCP) of the medial and lateral PF joints in the intact knee and in postreconstruction knees at each knee flexion angle (0°, 30°, 60°, and 90°). Each MCP was normalized to that of the intact knee. A statistical comparison was made between MCP in the intact and reconstructed knees.

RESULTS

The normalized MCP of the medial PF joint fixed at either 0° or 30° significantly increased at 60° of knee flexion (P = .036 and .042, respectively) and at 90° of knee flexion (P = .002 and .001, respectively). Conversely, the normalized MCP fixed at 60° and 90° remained at the same level as the intact knees at all angles of knee flexion. The normalized MCP of the lateral PF joint showed no significant difference at any fixation angle compared with intact knees.

CONCLUSION

To avoid excessive PF joint contact pressure after MPFL reconstruction, it may be best to fix polyester suture tape between 60° and 90° of knee flexion.

CLINICAL RELEVANCE

Fixation of the polyester suture tape with a knotless anchor for MPFL reconstruction should be at 60° to 90° of knee flexion to most closely restore PF joint contact pressures to that of the intact knee.

Isolated versus combined medial patellofemoral ligament reconstruction for lateral instability of the patella

INTRODUCTION

Medial patellofemoral ligament reconstruction (MPFLR) is regularly combined with a tibial tuberosity transfer (TTT) in cases of recurrent patellar instability with underlying structural deformity. However, these indications for a TTT have recently come into question. This study aimed to assess the traditional indications by comparing the outcomes of isolated and combined MPFLR for the treatment of recurrent lateral patellar dislocation.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies were those which reported the outcomes of either isolated or combined or both MPFLR. Studies were required to report at least one of the following: redislocation rate, revision due to instability, or the Kujala score.

RESULTS

We found no difference between isolated and combined MPFLR in terms of redislocation ( p = 0.48), revisions due to instability ( p = 0.36), positive apprehension tests ( p = 0.25), or the Kujala score ( p = 0.58). Combined reconstruction presented more complications compared to isolated procedures ( p = 0.05). Subgroup analysis revealed no significant difference between studies investigating isolated medial patellofemoral ligament reconstruction MPFLR performed in patients with normal tibial tuberosity-trochlear groove (TT-TG) distances only or in patients with both normal and elevated TT-TG distances.

CONCLUSIONS

According to the published data, there is no difference in outcomes between isolated and combined MPFLR. Underlying structural deformity did not demonstrate any significant effect on the success of the isolated MPFLR. Although there are definite indications for combined reconstruction, the current evidence suggests that our inclusion criteria may not be entirely correct. Further study is required to clarify and refine the true indications for combined MPFLR.

LEVEL OF EVIDENCE

III, meta-analysis of nonrandomized studies.

Selective bundle tensioning in double-bundle MPFL reconstruction to improve restoration of dynamic patellofemoral contact pressure

PURPOSE

To evaluate the optimal graft tension angles in a medial patellofemoral ligament (MPFL) reconstruction with selective bundle tensioning in order to restore patellofemoral contact pressure distributions closest to the native state.

METHODS

Twelve human cadaveric knee specimens were mounted with the femur on a custom-made fixation device allowing free range of motion in the knee joint for testing. Using a sensitive pressure film (Tekscan) patellofemoral contact pressure was measured in 15° intervals during a dynamic flexion movement from 0°-90° in the native state, in cut MPFL and after MPFL-reconstruction with a gracilis tendon. The graft was separated in two bundles and was fixed independently on the patella using two knotless anchors. Two groups were made with either the proximal or distal bundle fixed at the femur at a knee flexion angle of 30° and the corresponding other bundle subsequently fixed at the femur at 15°, 45°, 60°, 75° and 90° of knee flexion using extra-cortical fixation and controlled tension of 2N in both groups. The sequence of the flexion angles at the graft fixation was alternated. Pressure measurements were repeated after every fixation of the graft.

RESULTS

Cutting the MPFL resulted in significantly reduced patellofemoral contact pressure at all flexion angles. After MPFL reconstruction the patellofemoral contact pressure remained significantly reduced during dynamic knee flexion in all tested double-bundle combinations (p < 0.05) except for fixation of the proximal bundle in 30° and the distal bundle in 75°. Selective evaluation of lateral patellofemoral contact pressure, however, showed significant reduction in all tested double-bundle combinations (p < 0.05) from 15° to 90°. Evaluation of isolated medial patellofemoral pressure changes showed no significant difference in all tested combinations compared to the intact knee. Furthermore, evaluation of the isolated proximal and distal patellofemoral contact pressure also revealed a significantly reduced contact pressure in all tested double-bundle combinations (p < 0.05) except for fixation of the proximal bundle in 30° and the distal bundle in 75°.

CONCLUSION

According to this study, selective bundle tensioning in anatomic MPFL-reconstruction should be considered as an easy and more anatomic alternative to current popular techniques to restore patella kinematics and give clear recommendation about knee flexion angle and tension during fixation. Although tensioning two bundles separately may further improve clinical results. If performed, fixation of the graft is recommended under low tension (2N) with the proximal bundle at 30° and the distal bundle at 75° of knee flexion.

Graft choice for isolated MPFL reconstruction: gracilis versus semitendinosus

INTRODUCTION

After the first patellar dislocation, most patients report damage of the medio-patellofemoral ligament (MPFL) and surgical reconstruction is required. The purpose of this study is to systematically review current evidence and to clarify the role of the gracilis and semitendinosus tendons as graft for isolated MPFL reconstruction.

MATERIALS AND METHODS

The present systematic review was conducted according to the PRISMA guidelines. The literature search was conducted in October 2019. All clinical trials using the semitendinosus and/or gracilis tendon grafts for isolated MPFL reconstruction in patients with patellofemoral instability were considered for inclusion. Only articles reporting a minimum of 12-month follow-up were considered. The PEDro score was used for the methodological quality assessment.

RESULTS

Data from 1491 procedures were collected. The mean follow-up was 36.12 months. There was comparability among the patient baseline. All the scores of interests (Kujala, Tegner, Lysholm) and range of motion scored better in the semitendinosus group. Moreover, in favour of the semitendinosus group, a statistically significant reduction of the revision surgeries and re-dislocations were evidenced. Apprehension test and persistent instability sensation found any statistical correlations.

CONCLUSION

Isolated MPFL reconstruction through semitendinosus tendon graft performed better than the gracilis in selected patients suffering from recurrent patellofemoral instability.

Single- versus double-bundle patellar graft insertion for isolated MPFL reconstruction in patients with patellofemoral instability: a systematic review of the literature

INTRODUCTION

The MPFL reconstruction is performed either via a single-bundle (SB) or double-bundle (DB) procedure. The purpose of this study is to perform a systematic review comparing SB versus DB graft for recurrent patellofemoral instability, to summarize current evidence, and to clarify the role of both techniques. We focused on clinical scores, physical examination, complications, revision surgeries, and failures.

MATERIAL AND METHODS

In May of 2019 the main online databases were accessed. All the clinical studies treating isolated MPFL reconstruction for patellofemoral instability through a single and/or double-bundle graft were enrolled in the present systematic review. Only articles reporting primary isolated MPFL reconstruction, reporting a minimum of 12-months follow-up were considered for inclusion.

RESULTS

The scores of interest were in favour of the DB cohort: Kujala (+ 3.2, P = 0.03), Lysholm (+ 5.1, P = 0.001), Tegner (+ 0.3, P = 0.2), IKDC (+ 5.4, P = 0.01), VAS (+ 0.8, P = 0.3), ROM (+ 9.96, P = 0.04). In the DB graft, a reduction of overall complications (OR 0.59; P = 0.1), further surgeries (OR 0.64; P = 0.12) and re-dislocations (OR 0.61; P = 0.16) was observed. The SB group reported a reduction in the post-operative apprehension test (OR 2.42; P = 0.24).

CONCLUSION

Current study support the use of double-bundle tendon graft for isolated MPFL reconstruction in selected patients with recurrent patellofemoral instability.

Patellar fixation graft via suture anchors versus tunnel techniques during isolated MPFL reconstruction for recurrent patellofemoral instability: a systematic review of the literature

INTRODUCTION

There is still a lack of evidence concerning the patellar fixation of the medial patellofemoral ligament (MPFL) graft in selected patient with recurrent instability. The purpose of the present study was to investigate and compare clinical outcomes and further complications of isolated MPFL reconstruction via suture anchors versus tunnel techniques for recurrent patellofemoral instability.

MATERIALS AND METHODS

This systematic review of the literature was conducted according to the PRISMA guidelines. In September 2019, the main databases were accessed. All the clinical trials performing isolated MPFL reconstruction in patients with recurrent patellofemoral instability were included in the present study. Only articles fixing the MPFL graft through suture anchors and/ or patellar tunnel techniques were included in the analysis.

RESULTS

Data from 46 papers (1712 patients) were recorded. The mean follow-up was 40 ± 18 months. No differences were found in Kujala, Lysholm and Tegner score, International Knee Documentation Committee, visual analogic scale, range of motion and re-dislocation rate. The suture anchors fixation group detected reduced rate of apprehension test (OR: 0.6; p = 0.03), revision surgeries (OR: 0.4; p = 0.02) and anterior knee pain (OR: 0.05; p < 0.0001) and reduced not-classified complications (OR: 0.18; p < 0.0001).

CONCLUSION

Both the suture anchors and the bone-tunnels are a feasible option for isolated MPFL reconstruction in patients with recurrent patellofemoral instability. Patellar fixation via suture anchors evidenced a reduced rate of anterior knee pain, revision surgeries, apprehension test and an overall reduced complication compared to the bone-tunnel technique.

Medial patellofemoral ligament reconstruction using an autograft or allograft for patellar dislocation: a systematic review

Purposes

The purpose of this study is to review the use of an allograft or autograft in medial patellofemoral ligament (MPFL) reconstruction.

Materials and methods

Various electronic databases were searched for relevant articles published from January 2000 to September 2017 that evaluated clinical outcomes of MPFL reconstruction using an autograft or allograft. Data search, extraction, analysis, and quality assessments were performed based on Cochrane Collaboration guidelines.

Results

The study of 21 autografts and one allograft was included in this review. Although direct comparative studies were unavailable, the Kujala score and subjective results were reported in the majority of these studies. While the use of an autograft for MPFL reconstruction yielded satisfactory clinical outcomes with few perioperative complications, no new outcome has been drawn from the use of allografts.

Conclusions

Although many studies have shown favorable clinical results for MPFL reconstruction using an autograft, the clinical results of MPFL reconstruction using an allograft have not yet been sufficient to achieve meaningful clinical results due to low levels of evidence. Direct comparisons were not conducted because there were very few studies on allografts; thus, further research in this area should be performed in the future.

Electronic supplementary material

The online version of this article (10.1186/s43019-019-0008-0) contains supplementary material, which is available to authorized users.

Proof-of-concept prototype drill-guide for use in medial patello-femoral ligament (MPFL) reconstruction surgery

For surgical reconstruction of the medial patello-femoral ligament (MPFL) a variety of techniques are used for fixation of the graft to the medial border of the patella. The bone bridge or V-shaped tunnel technique utilises two tunnels drilled from the medial aspect of the patella that converge centrally creating a tunnel through which the graft is threaded. This technique has advantages: it avoids hardware (bone anchors) and their associated complications, creates a broad attachment of the ligament approximating normal anatomy and the tunnel does not breach the lateral cortex of the patella reducing the risk of patella fracture. In current practice the bony tunnels are created using freehand techniques. These rely on estimation of the patella centre by the surgeon and is subject to wide variation. Additionally this technique can be inefficient, inaccurate and time consuming. To address these disadvantages a new drill-guide device was developed. A prototype drill-guide was constructed using CAD and 3D printing methods. The device was designed to allow the surgeon to accurately and efficiently drill the required v-shaped bone tunnel. To assess the efficacy of the prototype drill guide, an experiment designed to assess a group of ten surgeons with an average of 4.2 years experience performing the task of creating a v-shaped bone tunnel using a free-hand technique and the drill-guide. To determine the accuracy of the tunnel placement, the angle between drill holes, distance from centre of the patella and the amount of over-drill were measured. Procedure duration was also compared. The results revealed that the prototype drill-guide created a more accurate bone bridge than the traditional free hand method. The root mean square error for the distance from centre was 0.50 mm vs 2.12 mm and the angle between tunnels was 2.6O vs 15.9O for the prototype and traditional methods respectively. There was a mean of 8.9 mm over-drill with the traditional method, which was negated when using the guide. Surgeons using the guide were approximately 25% faster than using the traditional free-hand technique. The prototype drill-guide improved the accuracy, reduced the variability, and reduced procedure duration compared to the traditional free-hand technique.

Middle-to long-term outcome after medial patellofemoral ligament reconstruction with Insall's proximal realignment for patellar instability

Background

Recently, medial patellofemoral ligament (MPFL) reconstruction has become a common, widely used procedure to treat patellar instability. However, few reports exist on the long-term outcome after MPFL reconstruction. We elucidated the middle- to long-term outcome after MPFL reconstruction with Insall’s proximal realignment. Methods: From 1999 to 2012, 42 knees of 32 patients who underwent MPFL reconstruction with Insall’s proximal realignment were reviewed with a minimum follow-up of five years. Patients who could visit our office and receive some designated examinations were included in this study. The re-dislocation rate and patellar apprehension sign postoperatively were evaluated. The Kujala score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were calculated. We assessed the images using plane x-ray and magnetic resonance imaging (MRI). The tilting angle (TA), congruence angle (CA), and lateral shift ratio (LSR) on the plane x-ray were measured pre- and postoperatively and at final follow-up. Using MRI, osteochondral lesions at the patellofemoral joint were evaluated.

Results

A total of 20 knees of 15 patients (two male, 13 female) who could visit our office were studied. The follow-up rate was 47.6%. The mean age at operation was 19.9 (11–41) years and mean follow-up was 123 (60–215) months. One knee (5.5%) had a history of postoperative subluxation, and five (25%) had a positive apprehension sign. The mean Kujala score significantly improved from 65.5 to 86.1 points (P < 0.05). The mean KOOS (symptom, pain, activities of daily living [ADL], sports, quality of life [QOL]) was 74.4, 92.4, 97.3, 84.1, and 73.2 points, respectively, at final follow-up. On the plane x-ray, patellofemoral alignment was improved postoperatively, and this improvement was maintained at final follow-up. On MRI, in five of 20 cases, the patellofemoral osteoarthritic change was observed at final follow-up. However, in four of these five knees with severe osteochondral lesions, osteochondral fixation or transplantation surgery had been performed. Only one of the remaining 15 knees had a patellofemoral osteoarthritic change observed at final follow-up.

Conclusion

Middle- to long-term outcome after MPFL reconstruction with Insall’s proximal realignment at our institution was evaluated, and good clinical results were observed. Most patients who did not have a severe cartilage lesion preoperatively did not develop osteoarthritic change.

Patellar Redislocation Rates and Clinical Outcomes After Medial Patellofemoral Ligament Reconstruction: Suture Anchor Versus Double Transpatellar Tunnel Fixation

BACKGROUND

Few studies to date have compared clinical outcomes in patients who have undergone medial patellofemoral ligament (MPFL) reconstruction using the suture anchor and double transpatellar tunnel fixation methods. This meta-analysis therefore compared the clinical results, including the patellar redislocation rate and improvement in functional scores, of suture anchor and double transpatellar tunnel fixation.

HYPOTHESIS

The recurrence rate and improvement in functional outcomes after surgery would be similar using the suture anchor and double transpatellar tunnel fixation methods.

STUDY DESIGN

Meta-analysis.

METHODS

Studies evaluating MPFL reconstruction using either the suture anchor or double transpatellar tunnel technique for patellar site fixation were included if they reported the patellar redislocation rate after surgery and/or validated patient-reported outcomes such as the Kujala and Lysholm scores.

RESULTS

Twenty-one studies were included in this meta-analysis. The mean patellar redislocation rates were similar using the suture anchor (3.2% [95% CI, 1.6%-6.2%]) and double transpatellar tunnel (3.4% [95% CI, 2.1%-5.4%]) techniques ( P = .879). The mean improvement in the Kujala score from before to after MPFL reconstruction was greater using the suture anchor (37.2 [95% CI, 31.1-43.4]) method than the double transpatellar tunnel method (28.7 [95% CI, 21.2-36.1]) ( P = .018). However, the mean improvement in the Lysholm score did not differ significantly using the 2 techniques.

CONCLUSION

The patellar redislocation rate did not differ significantly in patients who underwent MPFL reconstruction using the suture anchor and double transpatellar tunnel fixation methods. The suture anchor fixation method, however, resulted in a greater degree of improvement in patient-reported outcomes.

Single- and double-bundle medial patellofemoral ligament reconstruction procedures result in similar recurrent dislocation rates and improvements in knee function: a systematic review

PURPOSE

To evaluate medial patellofemoral ligament (MPFL) reconstruction using hamstring tendon autografts using single-bundle (SB) and double-bundle (DB) techniques, and compare the clinical outcomes including the Kujala score, postoperative apprehension, recurrent subluxation or dislocation, and complications.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched for relevant literature using the terms ''medial patellofemoral ligament'' and ''MPFL''. The pooled mean values of improvement in the Kujala score were calculated by random effects meta-analysis. Unweighted estimates for the rates of postoperative apprehension, recurrent subluxation or dislocation, and complications were determined by dividing the total number of occurrences by the total number of knees.

RESULTS

Thirty-one articles were included, involving 1063 patients (1116 knees). Two hundred and forty-four patients (254 knees) underwent SB reconstruction, while 819 patients (862 knees) underwent DB reconstruction. The pooled mean values of Kujala score improvement were similar in the SB group (30.1; 95% CI 26.6-33.6) and DB group (30.7; 95% CI 27.7-33.7). The SB group had a significantly greater rate of postoperative apprehension (7.9%) than the DB group (4.1%; P = 0.014). There were no significant differences between the two groups in the rates of recurrent subluxation or dislocation (1.2 and 1.6%) and complications (10.6 and 7.7%).

CONCLUSION

With variability in patient populations and surgical techniques, the DB procedure for isolated MPFL reconstruction demonstrates similar outcomes to the SB technique regarding improvement of knee function, recurrent subluxation or dislocation, and complications. The SB technique may have a greater risk of postoperative apprehension, whereas the DB technique may cause more stiffness.

LEVEL OF EVIDENCE

IV.

External focus training for reacquisition of knee function in a Down syndrome patient after surgery for recurrent patellar dislocation: a case report

[Purpose] This case study describes the reacquisition of knee joint function in a patient with Down syndrome after surgery for patellar dislocation using external focus training. [Participant and Methods] The patient was a female aged 24 years with Down syndrome and a low Intelligence Quotient, who suffered from right patellar dislocation. The range of motion in the right knee while walking was 2 to 23 degrees at 3 weeks after surgery. A compensatory gait while walking was confirmed, with her right leg fixed in extension. Her range of motion while lying was 0 to 155 degrees. A task in which the patient reached and touched a ball was performed with the lower extremities while lying down, according to simple instructions from a therapist. Instructions were given using a simple directive phrase. The intervention started with a single-joint exercise and progressed to a multi-joint exercise. [Results] The range of motion was 0 to 68 degrees at 9 weeks after surgery. Her compensatory gait disappeared and she was able to walk more than 2 km. [Conclusion] Even though the patient's low cognitive function made it difficult for her to complete some tasks, training based on external focus enabled her to acquire adequate knee joint function. External focus training was found to be effective for a patient with a low Intelligence Quotient.

Anatomic double-bundle medial patellofemoral ligament reconstruction with aperture fixation using an adjustable-length loop device: a 2-year follow-up study

Background

To assess the clinical availability of an adjustable-length loop device for use in the double-bundle technique with aperture fixation at the patella and femur during anatomic double-bundle medial patellofemoral ligament reconstruction (DB-MPFLR) for recurrent patellar dislocation.

Methods

We retrospectively investigated 11 patients (12 knees) with recurrent patellar dislocation who underwent anatomic DB-MPFLR with an ipsilateral semitendinosus tendon autograft. The graft was folded in half, and its central portion was hanged using the adjustable-length loop device. Both free ends of the graft were fixed at the proximal and distal ends of the medial edge of the patella by using suture anchors, and the hanged graft loop was pulled into the femoral tunnel while maintaining equal tension on both bundles. Manual traction of the suture loops was applied to fix the graft appropriately in full range of motion (ROM) of the knee joint under arthroscopic guidance. Clinical outcomes such as re-dislocation, ROM, clinical scores (Kujala score, Lysholm score, and visual analogue scale score for anterior knee pain), and complications were assessed preoperatively and at 2 years postoperatively. Radiographic parameters indicating patellar position, including congruence angle and lateral patellofemoral angle, were measured at 4 different angles of knee flexion (30°, 45°, 60°, and 90°).

Results

At 4 different flexion angles of the knee joint, the preoperative congruence angle decreased significantly and the lateral patellofemoral angle increased significantly at the final follow-up (P <  0.001). Notably, the improvements in these angles were maintained with no significant differences at the 4 different flexion angles. None of the patients experienced subluxation or re-dislocation after surgery. The patellar instability symptoms improved, as confirmed on the basis of radiographic and other clinical outcomes.

Conclusion

New DB technique with aperture fixation at the patella and femur by using an adjustable-length loop device offers high stability with full ROM of the knee joint, can be considered as a feasible procedure and technique for recurrent patellar dislocation.

Return-to-Play Guidelines After Medial Patellofemoral Ligament Surgery for Recurrent Patellar Instability: A Systematic Review

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction and repair continue to gain acceptance as viable treatment options for recurrent patellar instability in patients who wish to return to sports after surgery. Return-to-play guidelines with objective or subjective criteria for athletes after MPFL surgery, however, have not been uniformly defined.

PURPOSE

To determine whether a concise and objective protocol exists that may help athletes return to their sport more safely after MPFL surgery.

STUDY DESIGN

Systematic review.

METHODS

The clinical evidence for return to play after MPFL reconstruction was evaluated through a systematic review of the literature. Studies that measured outcomes for isolated MPFL surgery with greater than a 12-month follow-up were included in our study. We analyzed each study for a return-to-play timeline, rehabilitation protocol, and any measurements used to determine a safe return to play after surgery.

RESULTS

Fifty-three studies met the inclusion criteria, with a total of 1756 patients and 1838 knees. The most commonly cited rehabilitation guidelines included weightbearing restrictions and range of motion restrictions in 90.6% and 84.9% of studies, respectively. Thirty-five of 53 studies (66.0%) included an expected timeline for either return to play or return to full activity. Ten of 53 studies (18.9%) in our analysis included either objective or subjective criteria to determine return to activity within their rehabilitation protocol.

CONCLUSION

Most studies in our analysis utilized time-based criteria for determining return to play after MPFL surgery, while only a minority utilized objective or subjective patient-centric criteria. Further investigation is needed to determine safe and effective guidelines for return to play after MPFL reconstruction and repair.

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

PURPOSE

To determine whether graft selection or patient age affects the following after isolated medial patellofemoral ligament (MPFL) reconstruction: (1) rates of recurrent instability, (2) rates of postoperative complications (other than instability), and (3) subjective symptom improvement.

METHODS

A systematic search identified studies reporting outcomes for isolated MPFL reconstruction. Rates of recurrent instability, subjective Kujala knee function scores, and complications were tabulated. Symptom improvement was defined as change in Kujala score (preoperative evaluation to final follow-up).

RESULTS

Forty-five studies were included with 27 documented cases of recurrent instability among 1,504 patients (1.8%); instability rates ranged from 0% to 20.0% overall; among autograft in adults, 0% to 11.1% (1.4%, 18/1,260); among autograft in adolescents, 0% to 20% (10.0%, 8/80); among allograft, 0% (0/65 cases); and among synthetic, 0% to 3.3% (1.3%, 1/76). Among autograft choices in adults, rates of recurrent instability were low; recurrence with gracilis ranged from 0% to 11.1% (0.9%, 1/116); with semitendinosus, 0% to 6.3% (0.6%, 4/676); with quad or patellar tendon, 0% (0/65); and with adductor tendon, 5.6% to 8.3% (6.7%, 2/30). Complication rates ranged from 0% to 34.4%. All included studies reported significant improvement in Kujala scores after surgery (P < .01). There was significant heterogeneity in effect size and evidence of reporting bias among small studies, precluding reliable pooled analysis of treatment effect.

CONCLUSIONS

Autograft is not superior to allograft or synthetic grafts for isolated reconstruction of the MPFL, and rates of recurrent instability are generally low. Isolated MPFL reconstruction can provide significant symptom relief regardless of graft selection, although there is a bias toward reporting better than expected results among smaller studies. Pediatric patients and patients treated with adductor tendon autograft have higher recurrent instability rates. While caution should be used in making definitive recommendations secondary to the small number of allograft and synthetic studies, selection of graft type based on surgeon preference, comfort, and prior experience remains appropriate.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I to IV studies.

Medial Patellofemoral Ligament Reconstruction: Impact of Knee Flexion Angle During Graft Fixation on Dynamic Patellofemoral Contact Pressure-A Biomechanical Study

PURPOSE

Objective evaluation of the optimal graft tension angle to fully restore patellofemoral contact pressure in reconstruction of the medial patellofemoral ligament (MPFL) in comparison to the native knee.

METHODS

Twelve cadaveric knee specimens were fixed in a custom-made fixation device. A sensitive pressure film (Tekscan) was fixed in the patellofemoral joint, and patellofemoral contact pressure was assessed during a dynamic flexion movement from 0° to 90°. The MPFL was cut and measurements were repeated. Reconstruction of the MPFL was performed with the gracilis tendon subsequently fixed in the femur at 15°, 30°, 45°, 60°, 75°, and 90° of knee flexion under controlled tension (2 N). The sequence of the flexion angles was alternated. Pressure measurements were repeated after every fixation of the graft.

RESULTS

No significant differences were seen in the overall patellofemoral contact pressure compared to the native knee (P > .05). However, medial patellofemoral pressure showed a significant increased patellofemoral contact pressure after MPFL reconstruction at a knee flexion angle during graft fixation of 15° (P = .027), 45° (P = .050, P = .044), and 75° (P = .039). Moreover, proximal/distal patellofemoral contact pressure revealed a significantly reduced contact pressure at 15° (P = .003), 30° (P = .009), 45° (P = .025), 75° (P = .021), and 90° (P = .022) of flexion distal after MPFL reconstruction compared with the intact knee. Lateral patellofemoral contact pressure was significantly reduced in all performed reconstructions (P < .05).

CONCLUSIONS

The flexion angle during graft fixation for MPFL reconstruction did not have a significant impact on the overall patellofemoral contact pressure. However, selective medial, proximal, distal, and lateral patellofemoral contact pressure was significantly altered for all reconstructions. Fixation of the MPFL graft at 60° of flexion was able to most closely restore patellofemoral contact pressure compared with the intact knee.

CLINICAL RELEVANCE

Based on the findings of the present study, fixation of the graft in anatomic reconstruction of the MPFL should be considered in 60° of flexion under low tension (2 N) to most closely restore patellofemoral contact pressure compared with the native knee.

Effect of Transosseous Tunnels on Patella Fracture Risk After Medial Patellofemoral Ligament Reconstruction: A Cadaveric Study

PURPOSE

To determine whether (1) tunnels that breach the anterior cortex of the patella result in increased fracture risk and (2) transosseous tunnels drilled across the patella significantly reduce the tensile force needed to fracture the patella.

METHODS

Twenty-six fresh-frozen cadaveric human patellas were randomized to 1 of 3 groups: a control group with unmodified patellas, a group with 2 transverse tunnels (TT) that did not breach the anterior cortex, and a group with 2 TT that breached the anterior cortex of the patella (PA). Patellas were connected in series to a load cell via freeze clamp attachments to the quadriceps and patellar tendons. Pull was fixed at 45° with the patella set in the trochlear groove of a synthetic femur. Patellas were loaded cyclically, then to failure.

RESULTS

Twenty-six patellas were tested (mean age = 71.4 years; range = 37-95, standard deviation [STD] = 11.5 years). PA patellas were more likely to fracture through the tunnel than TT patellas (100% vs 25%, P = .033). Control, TT, and PA groups failed at 1,915 N (STD = 508 N), 1,901 N (STD = 884 N), and 1,640 N (STD = 625 N), respectively. There was no statistically significant difference in overall load to failure between control and TT (P = .969), control and PA (P = .321), and TT and PA (P = .488) groups.

CONCLUSIONS

Transosseous patellar tunnels for medial patellofemoral ligament reconstruction that breached the anterior cortex were more likely to fracture during longitudinal load than those that did not breach the anterior cortex. However, we found no statistically significant difference in the tensile load to failure between native patellas and patellas with either type of transosseous tunnel.

CLINICAL RELEVANCE

The results of this study show that breaching the anterior cortex during transosseous drilling increases the risk of a patellar fracture occurring through the transosseous tunnel.

Anthropometric and Skeletal Parameters Predict 2-Strand Semitendinosus Tendon Size in Double-Bundle Anterior Cruciate Ligament Reconstruction

Background:

Few studies have examined whether skeletal parameters predict hamstring graft size during anterior cruciate ligament reconstruction (ACLR).

Purpose/Hypothesis:

The purpose of this study was to examine whether preoperative anthropometric and radiographic skeletal parameters could predict hamstring graft size during ACLR. We hypothesized that both anthropometric and skeletal parameters can be used to predict graft size in our double-bundle procedure and that the use of skeletal parameters will improve the accuracy of graft size prediction.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 200 patients were recruited and underwent double-bundle ACLR using a semitendinosus (ST) graft. The harvested tendon was measured to determine graft length (GL) and then split at its midpoint. The graft diameters of the anteromedial (GD_AM) and posterolateral bundles (GD_PL) were measured at the femoral aspect of the 2-stranded graft. The mean diameters of both bundles were included in the analysis. On the coronal radiograph, femorotibial angle (FTA), femoral interepicondylar distance (IED), and tibial plateau width (coronal tibial width [CTW]) were measured. Blumensaat line length (BLL) and the lateral tibial width (LTW) were measured on the lateral radiograph. A linear regression analysis was conducted using graft size as the dependent variable and age, sex, height, weight, Tegner activity score, and skeletal parameters as the independent variables.

Results:

Mean GL was 258.9 ± 21.9 mm, GD_AM was 5.9 ± 0.5 mm, and GD_PL was 5.7 ± 0.6 mm. Single regression analysis showed that GL was significantly predicted by sex, height, weight, Tegner activity score, IED, CTW, BLL, and LTW (R² range, 0.033-0.342). GD was predicted by sex, height, weight, IED, CTW, BLL, and LTW (R² range, 0.094-0.207). Stepwise multiple linear regression analysis significantly confirmed sex, height, and age as the variables to comprehensively predict GL (R² = 0.384). With regard to GD, stepwise multiple regression confirmed height and IED as significant variables (R² = 0.224).

Conclusion:

Both preoperative anthropometric and radiographic parameters on plain radiographs were able to predict harvested GL and 2-strand GD. Multivariate regression slightly improved the prediction of graft dimensions compared with univariate regression.

Influence of graft source and configuration on revision rate and patient-reported outcomes after MPFL reconstruction: a systematic review and meta-analysis

PURPOSE

The purpose of this systematic review and meta-analysis was to determine the influence of graft source (allograft vs. autograft) and configuration (single-limbed vs. double-limbed) on failure rate and disease-specific patient-reported outcome (Kujala score) after medial patellofemoral ligament (MPFL) reconstruction for patellar instability.

METHODS

A systematic review of PubMed, Scopus, and the Cochrane Library was performed. A total of 31 studies met inclusion/exclusion criteria and were used to extract cohorts of patients who underwent ligament reconstruction with various allograft, autograft, single-limbed, and double-limbed constructs. Failure rates and postoperative improvements in Kujala scores were compared between cohorts using inverse-variance weighting in a random-effects analysis model and appropriate comparative statistical analyses (Chi-squared and independent samples t tests).

RESULTS

A total of 1065 MPFL reconstructions were identified in 31 studies. Autograft reconstructions were associated with greater postoperative improvements in Kujala scores when compared to allograft (32.2 vs. 22.5, p < 0.001), but there was no difference in recurrent instability (5.7 vs. 6.7 %, p = 0.74). Double-limbed reconstructions were associated with both improved postoperative Kujala scores (37.8 vs. 31.6, p < 0.001) and lower failure rate (10.6 vs. 5.5 %, p = 0.030).

CONCLUSION

MPFL reconstructions should be performed using double-limbed graft configurations. While autograft tendon may be associated with higher patient-reported outcomes in the absence of associated connective tissue disorders or ligamentous laxity, patient factors and allograft processing techniques should be carefully considered when selecting an MPFL graft source, as revision rates were no different between graft sources.

LEVEL OF EVIDENCE

IV.

Medial patellofemoral ligament reconstruction using a bone groove and a suture anchor at patellar: a safe and firm fixation technique and 3-year follow-up study

Background

Graft fixation is critical to the restoration of the medial patella of femoral ligament function and long-term success. Numerous fixations at the patella have been described, while the complications including patellar fractures, violation of the posterior patella and delay of tendon-to-bone healing remain significant challenges. Here, we describe a safe and firm fixation at the patellar for medial patellofemoral ligament (MPFL) reconstruction and explore the safety angle of drilling the suture anchor at different morphology of the patellar. Moreover, we evaluate the results at a 3-year follow-up.

Methods

Combined bone groove and suture anchor fixation at the patella was performed on 26 patients (16 females, 10 males; mean age 26.3 ± 4.7 years) diagnosed with recurrent patellar dislocation. The drilling direction of the suture anchor referred to the safety angle according to the Wiberg type classification. The safety angle was defined as the angle between the drill tunnel and a line that connected the medial and lateral margins of the patella and was established following computed tomography assessment of 117 patients who were diagnosed with patellar dislocation in our hospital according to the Wiberg type classification (I:29, II:65, III:23). X-ray, Lysholm, Kujala and Tegner scores were obtained preoperatively and at the time of final follow-up.

Results

There were no patellar complications, including fracture and redislocation. Average congruence, patella tilt angles and lateral patella angle were significantly changed (P < 0.01). The Lysholm, Kujala and Tegner scores were significantly increased (P < 0.01). The safe angles of male and female patients according to the patellar Wiberg type classification were less than 45.32 ± 1.76 and 41.20 ± 1.33, 69.74 ± 1.38 and 63.66 ± 1.45 and 84.11 ± 1.67 and 80.26 ± 1.73, respectively.

Conclusions

We achieved encouraging results with this fixation at the patellar. When drilling from Wiberg type I to type III patellar, the suture anchor should be more vertical. When fixing the patellar of female patients, the drilling suture anchor should be more sloping.

Reconstruction of the medial patellofemoral ligament by means of the anatomical double-bundle technique using metal anchors

Objective

To evaluate double-bundle reconstruction of the medial patellofemoral ligament (MPFL) using a graft from the semitendinosus tendon and fixation with metal anchors over the medium term.

Methods

This was a prospective cross-sectional study. After approval from the research ethics committee, 31 patients with patellofemoral instability who underwent MPFL reconstruction by means of the anatomical double-bundle technique, with fixation using metal anchors, were analyzed between May 2010 and January 2015. To evaluate the effectiveness of the MPFL reconstruction surgery, the Kujala scale and the Tegner–Lysholm score were assessed before the procedure and one year afterwards, along with clinical data such as pain levels, range of motion and J sign. The data were tabulated in the Excel^® software and were analyzed using the SPSS Statistics^® software, version 21. The statistical analysis was performed using the Wilcoxon T test and the McNemar test.

Results

The mean preoperative score from the Kujala test was 45.64 ± 1.24 and the postoperative score was 94.03 ± 0.79 (p < 0.001). The preoperative Tegner–Lysholm score was 40.51 ± 1.61 and the postoperative score was 91.64 ± 0.79 (p < 0.001). The preoperative range of motion was 125.96 ± 2.11 and the postoperative range was 138.38 ± 1.49 (p < 0.05).

Conclusion

MPFL reconstruction by means of the anatomical double-bundle technique is easily reproducible, without episodes of recurrence, with satisfactory results regarding restoration of stability and function of the patellofemoral joint.

"Basket weave technique" for medial patellofemoral ligament reconstruction: Clinical outcome of a prospective study

BACKGROUND

Bone tunneling and implants with rigid fixations for medial patellofemoral ligament (MPFL) reconstruction are known to compromise results and are avoidable, especially in skeletally immature subjects. This study was to assess if these deficiencies were overcome with the technique devised by the author which avoids implants and bone tunnels. Results were assessed for complication rate and outcome.

MATERIALS AND METHODS

Fifty six knees of recurrent lateral patellar dislocation were treated in the past 49 months by MPFL reconstruction. Thirty nine were female and 17 male knees. The mean age was 20.6 years (range 9-48 years). Mean followup was 26 months. Five knees had previously failed stabilization procedures. Thirty one cases had Dejours Type A or B and 12 had Type C trochlear dysplasia. Arthroscopy was performed for associated injuries and loose bodies. Seven knees required loose body removal. Five knees underwent lateral retinacular release. Four knees had tibial tuberosity transfer. One knee had an associated anterior cruciate ligament reconstruction. An anatomical MPFL reconstruction was performed using hamstring autograft without the need for intraoperative fluoroscopy. Only soft tissue fixation was necessary with this newly devised technique and suturing. A rapid rehabilitation protocol was implemented with monthly followup until normalcy and 6 monthly thereafter.

RESULTS

All achieved full range of motion and normal mediolateral stability. There was no recurrence of dislocation. No major surgery related complications. One patella fracture at 8 months was due to a fall developed terminal restriction of flexion. Those in sports could return to their sporting activities (Tegner 1-9). Cases with osteochondral fractures had occasional pain that subsided in 1 year. Mean Kujala score improved from 64.3 to 99.69 with KOOS score near normal in all.

CONCLUSION

This new method of MPFL reconstruction gives excellent results. It avoids complications related to bone tunneling and implants. It is a safe, effective, reliable and reproducible technique.

The triangle zone as a femoral attachment location in medial patellofemoral ligament reconstruction: An in vivo three-dimensional analysis using an open MRI scanner

BACKGROUND

The exact isometric points for medial patellofemoral ligament (MPFL) fixation during MPFL reconstruction remain a matter of debate.

PURPOSE

The aim of this study was to characterize the functional length changes of various patellar and femoral fixation sites using in vivo three-dimensional (3D) movement patterns and to determine the ideal fixation sites at which the graft remains largely isometric.

METHODS

Twelve right knees of healthy volunteers were examined at early flexion angles (0°, 10°, 20°, 30°, 40°, 50°, and 60°) with a horizontal-type open magnetic resonance scanner, and 3D models were reconstructed using the marching cubes algorithm. Six points on the femoral condyle and three points on the medial aspect of the patella were simulated. The matching points represented the MPFL, which crossed the bony obstacle. The MPFL length changes were analyzed at various flexion degrees.

RESULTS

The lengths from the dome of Blumensaat's line (G), the point 10mm inferior to the adductor tubercle (H), to the midpoint between the adductor tubercle and the medial epicondyle (I) were more isometric than other points. The lengths between the dome of Blumensaat's line and the superior pole of the patella changes significantly between 20° and 60° of flexion (p=0.040).

CONCLUSIONS

The femoral fixation site may be more accurately located during MPFL reconstruction at the G, H, and I points to restore the native biomechanical function of the MPFL. The dome of Blumensaat's line should be avoided during MPFL reconstruction with the superficial quad technique.

CLINICAL RELEVANCE

A triangular region composed of the dome of Blumensaat's line, 10mm inferior to the adductor tubercle, and the midpoint between the adductor tubercle and medial epicondyle is recommended as the femoral fixation site.

The double-pulley technique for anatomical double-bundled medial patellofemoral ligament reconstruction

INTRODUCTION

Majority of the current medial patellofemoral ligament (MPFL) reconstruction techniques vary with respect to methods of fixation on the patella. In an effort to maximise the area of patellar footprint coverage and minimise the complication of patellar fracture, we developed a procedure that implemented the double-pulley suture anchors technique.

DESIGN

Prospective case series.

SETTING

A primary medical centre in Kaohsiung, Taiwan.

PATIENTS AND METHODS

Eighteen consecutive patients (18 knees) who met the inclusion criteria underwent the aforementioned operation between January 2010 and March 2012. Patients were evaluated using functional scores (Kujala and Tegner-Lysholm scores), apprehension test, and radiographic examination (congruence angle and patellar tilting angle) preoperatively and at the follow-up.

RESULTS

The mean follow-up was 35 months. A firm endpoint to lateral patellar translation was noted in all patients at the last follow-up with a mean lateral translation quadrant of 1.5 (improved from 3.5 preoperatively, p<0.001). Both clinical and radiographic assessment improved significantly (p<0.001); the mean Kujala score improved from 55.3±6.8 preoperatively to 95.2±3.5 at the last follow-up; TegnerLysholm from 43.6±8.1 to 93.6±6.8; the mean congruence angle improved from 20.6°±2.1° preoperatively to -5.2°±2.4° at the last follow-up; and the patellar tilting angle from 23.8°±2.3° to 9.6°±1.3°.

CONCLUSION

The double-pulley patellar fixation technique, by having a result that is comparable with those of other studies that used aperture fixation techniques, can be a promising surgical option for anatomically reconstructing the medial petellofemoral ligament.

Widespread Implementation of Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability Maintains Functional Outcomes at Midterm to Long-Term Follow-up While Decreasing Complication Rates: A Systematic Review

PURPOSE

Our primary purpose was to evaluate whether complications have increased or functional outcomes have changed as medial patellofemoral ligament (MPFL) reconstruction has been adopted by more surgeons at more institutions over recent years. Our secondary purpose was to further define the complication profile of MPFL reconstruction.

METHODS

A systematic review of the literature was performed on January 12, 2014, using the keywords "medial patellofemoral ligament reconstruction," "patellar instability reconstruction," "patellofemoral ligament reconstruction," and "MPFL." Articles meeting our inclusion criteria were reviewed. Outcome measures, functional failures, complications, graft choice, and surgical technique were recorded and analyzed.

RESULTS

Thirty-four articles met our exclusion and inclusion criteria and were reviewed. Nineteen articles were "new" additions to the literature, whereas 15 had previously been reported on in prior analyses ("old"). The 19 new articles reported a statistically significant decrease in functional failure rates, from 9.55% in older studies to 4.77% in more recent studies (P < .001). The major complication rate dropped from 2.01% to 0.46% in the newer studies (P = .005), and the minor complication rate decreased from 6.53% to 4.00% (P = .06). Postoperative Kujala scores did not show a statistically significant change between newer and older publications (89.0 [SD, 3.7] and 89.4 [SD, 4.9], respectively; P = .55). Comparing results by fixation type, as well as by graft choice, showed no statistically significant differences in terms of outcomes or complication profile.

CONCLUSIONS

With nearly twice the number of medical centers performing reconstruction of the MPFL and outcomes reported on nearly double the number of patients in recent years, functional outcomes remain favorable as complication and failure profiles are improving. Furthermore, despite a wide array of fixation techniques, as well as multiple options for graft constructs, there are no statistically or clinically significant differences in functional outcomes over time. This finding highlights the efficacy and adoptability of MPFL reconstruction for the treatment of recurrent patellar instability.

LEVEL OF EVIDENCE

Level IV, systematic review of mixed-level studies.

Length change behavior of virtual medial patellofemoral ligament fibers during in vivo knee flexion

BACKGROUND

In vivo length change behavior of native medial patellofemoral ligament (MPFL) fibers throughout the range of knee motion has not been reported in vivo.

PURPOSE

To measure the length changes of various fibers of the MPFL and to determine their length change patterns during in vivo passive knee flexion.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The right knees of 11 living subjects were scanned with a high-resolution computed tomography scanner at 0°, 30°, 60°, 90°, and 120° of knee flexion, and 3-dimensional (3D) models were constructed using customized software. Five patellar points were determined: 20% (point 20), 30% (point 30), 40% (point 40), 50% (point 50), and 60% (point 60) from the superior pole of the patella. The Schöttle femoral point (point F) was marked on a translucent 3D model of a true lateral view. Five virtual fibers connecting these points on the 3D knee model were created, and the lengths of various fibers were digitally measured.

RESULTS

The average length changes were 9.1±2.5 mm in F20, 9.1±2.5 mm in F30, 8.1±2.6 mm in F40, 6.9±2.4 mm in F50, and 6.9±1.7 mm in F60. There were significant differences in length changes of these 5 fibers (P<.001). The lengths of 2 superior fibers (F20 and F30) increased as the knee flexed from 0° to 30° and decreased as the knee flexed over 30°. The lengths of a middle fiber (F40) and an inferior fiber (F50) increased from 0° to 30°, reached a plateau from 30° to 60°, and then decreased from 60° to 120°. F60 showed an increase from 0° to 30°, and then a plateau pattern from 30° to 90°, followed by a decrease during further flexion.

CONCLUSION

Superior fibers exhibited their maximum lengths at low flexion angles, and inferior fibers exhibited their maximum lengths at midflexion angles. The MPFL is a complex of functionally various fibers with some taut and others slack over the whole range of knee motion.

CLINICAL RELEVANCE

The results for lengths and length change patterns of various MPFL fibers are expected to serve as a theoretical background for anatomic double-bundle MPFL reconstruction.

MPFL reconstruction using a quadriceps tendon graft: part 1: biomechanical properties of quadriceps tendon MPFL reconstruction in comparison to the Intact MPFL. A human cadaveric study

BACKGROUND

The aim of this study was to analyze the structural properties of the original MPFL and to compare it to a MPFL-reconstruction-technique using a strip of quadriceps tendon.

METHODS

In 13 human cadaver knees the MPFLs were dissected protecting their insertion at the patellar border. The MPFL was loaded to failure after preconditioning with 10 cycles in a uniaxial testing machine evaluating stiffness, yield load and maximum load to failure. In the second part Quadriceps-MPFL-reconstruction was performed and tested in a uniaxial testing machine. Following preconditioning, the constructs were cyclically loaded 1000 times between 5 and 50 N measuring the maximum elongation. After cyclic testing, the constructs have been loaded to failure measuring stiffness, yield load and maximum load. For statistical analysis a repeated measures (RM) one-way ANOVA for multiple comparisons was used. The significance was set at P<0.05.

RESULTS

During the load to failure tests of the original MPFL the following results were measured: stiffness 29.4 N/mm (+9.8), yield load 167.8 N (+80) and maximum load to failure 190.7 N (+82.8). The results in the QT-technique group were as follows: maximum elongation after 1000 cycles 2.1 mm (+0.8), stiffness 33.6 N/mm (+6.8), yield load 147.1 N (+65.1) and maximum load to failure 205 N (+77.8). There were no significant differences in all tested parameters.

CONCLUSIONS

In a human cadaveric model using a strip of quadriceps-tendon 10 mm wide and 3mm deep, the biomechanical properties match those of the original MPFL when tested as a reconstruction.

CLINICAL RELEVANCE

The tested QT-technique shows sufficient primary stability with comparable biomechanical parameters to the intact MPFL.

The horizontal Y-shaped graft with respective graft tension angles in anatomical two-bundle medial patellofemoral ligament reconstruction

PURPOSE

Various techniques for medial patellofemoral ligament (MPFL) reconstruction have been described with two bundles of graft tensioned simultaneously. The present study was to introduce an anatomical reconstruction procedure using a horizontal Y-shaped graft with respective graft tension angles and report the preliminary results.

METHODS

A surgical technique for MPFL reconstruction using a horizontal Y-shaped semitendinosus tendon autograft with two bundles tensioned at 0° and 30° of knee flexion was described in detail. The patellar stability was evaluated with the apprehension test and an axial computed tomography (CT) scan at 30° of knee flexion. The knee function was evaluated using the Lysholm and Kujala scores.

RESULTS

No recurrent dislocation or subluxation was reported for 45 patients at a mean of 33.7-month follow-up. On CT images, congruence angle, patellar tilt angle, lateral patellar angle and lateral displacement were restored to the normal range. At the last follow-up, the mean Lysholm score improved from 51.8±6.2 to 91.7±4.1 and mean Kujala score was from 53.4±5.3 to 90.9±6.6 (P<0.01).

CONCLUSIONS

The present anatomical MPFL reconstruction technique with a horizontal Y-shaped two-bundle graft tensioned at respective knee flexion angles could not only recreate the fan-shape of MPFL but also mimic the function bundles of native ligament. Clinical follow-up confirms the good restoration of the patellar stability and significant improvement of knee function without special complications.

LEVEL OF EVIDENCE

Therapeutic, Level IV.

Anatomic medial patellofemoral ligament reconstruction using patellar suture anchor fixation for recurrent patellar instability

PURPOSE

The purpose of this study was to prospectively evaluate clinical and radiographic outcomes following anatomic medial patellofemoral ligament (MPFL) reconstruction using patellar suture anchor fixation for recurrent patellar instability.

METHODS

Twenty patients (20 knees) were enrolled in this study. The median age was 21 years, and the median follow-up was 34.5 months. Reconstruction was performed using a hamstring autograft fixed with two suture anchors at native patellar site of the MPFL. No patient had undergone additional medial tibial tuberosity transfer. Clinical scores (Kujala, Lysholm, and Tegner score) and apprehension test were completed preoperatively and at the follow-up. Preoperative and follow-up radiographic assessments included modified Insall-Salvati ratio, congruence angle, and lateral patellofemoral angle.

RESULTS

The preoperative Kujala and Lysholm scores were 52.6±12.4 and 49.2±10.7, and at follow-up visits, corresponding values were 90.9±4.5 (p<0.001) and 90.9±5.2 (p<0.001). Tegner score increased from 3.0 (range 1-4) to 5.0 (range 4-7) (p<0.001). The apprehension test was positive in all patients preoperatively, but only positive in one patient at follow-up. All radiographic assessments were significantly improved; modified Insall-Salvati index (from 1.75 to 1.65) (p=0.002), congruence angle (from 6.3° to -7.0°) (p<0.001), and lateral patellofemoral angle (from 2.1° to 4.9°) (p=0.008). No patient experienced a patellar fracture or redislocation.

CONCLUSION

These results are comparable to those of bone tunnel techniques reported in the literature. This study shows that anatomic MPFL reconstruction using two suture anchors is a reliable treatment option.

LEVEL OF EVIDENCE

Case series with no comparison group, Level IV.

Medial Patellofemoral Ligament Reconstruction for Patellar Dislocation: A Systematic Review

Background:

With improved understanding of the biomechanical importance of the medial patellofemoral ligament (MPFL), its reconstruction for patellar dislocation has become increasingly popular. The aim of this systematic review was to critically determine the effectiveness of MPFL reconstruction for patellar dislocation.

Hypothesis:

MPFL reconstruction for patellar dislocation leads to a low redislocation rate with improved Kujala scores.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A literature search was performed using Embase and Medline (Ovid) databases. Inclusion criteria included first-time and recurrent patellar dislocation, subluxation, or persistent instability with a minimum follow-up of 12 months and documentation of postoperative redislocation rate or Kujala score. The studies were systematically appraised, and a meta-analysis was performed.

Results:

Twenty-two studies were included: 2 randomized controlled trials, 3 parallel case series, and 17 case series. There were a total of 655 knees in the review, with an age range at time of surgery from 11 to 52 years. The pooled postoperative redislocation rate from all 17 case series showed a mean of 2.44%. The pooled preoperative Kujala scores from 12 case series showed a mean of 51.6 (95% CI, 46.71-56.49). The pooled postoperative Kujala scores from 16 case series showed a mean of 87.77 (95% CI, 85.15-90.39).

Conclusion:

Although the studies were of low quality, the meta-analysis of 17 case series shows that MPFL reconstruction for recurrent patellar dislocation results in a significant improvement in Kujala scores, a low redislocation rate, and acceptable complication rate. Randomized trials would be needed to draw influences on the superiority of MPFL reconstruction compared with other treatments.

Simultaneous medial and lateral patellofemoral ligament reconstruction for combined medial and lateral patellar subluxation

Medial patellar subluxation (MPS) is a disabling, often iatrogenic patellar instability due to previous lateral release for patellar instability. Lateral release destabilizes the patella on the lateral side, worsening the initial lateral instability and causing MPS. MPS is poorly recognized and may range from subluxation to true dislocation. This report describes a technique developed in response to episodes of medial and lateral patellar subluxation after failed lateral release for patellar instability. The technique uses a graft that extends from the medial patellofemoral ligament origin through the quadriceps tendon to the lateral epicondyle, thereby reconstructing both the medial and lateral patellofemoral ligaments, as well as providing simultaneous stability to both the medial and lateral sides of the patella.

An isolated medial patellofemoral ligament reconstruction with patellar tendon autograft

The aim of the study was to evaluate the results of the medial patellofemoral ligament reconstruction with a medial strip of patellar tendon autograft after a minimum 2-year followup. Ten patients (10 knees) were operated on by one surgeon, according to the modified technique, described by Camanho, without any bone plug at free graft end. The mean age of the patients was 27.2 years (ranging from 18 to 42 years). The mean follow-up period was 3 years and 7 months. All patients were reviewed prospectively. At the last follow-up visit, all the patients demonstrated a significant improvement in terms of patellofemoral joint stability, all aspects of the KOOS questionnaire, and Kujala et al.'s score (59.7 points preoperatively and 84.4 points at the last followup). No patient revealed recurrent dislocation. The SF-36 score revealed a significant improvement in bodily pain, general health, physical role functioning, social role functioning, and physical functioning domains. The described MPFL reconstruction with the use of the medial 1/3rd of patella tendon is an effective procedure that gives satisfactorily patellofemoral joint functions, improves the quality of life, and provides much pain relief. It is relatively simple, surgically not extensive, and economically cost-effective procedure.

Double-bundle medial patellofemoral ligament reconstruction with hamstring tendon autograft and mediolateral patellar tunnel fixation: a meta-analysis of outcomes and complications

Medial patellofemoral ligament (MPFL) reconstruction is used to treat patellar instability and recurrent patellar dislocation. Anatomical studies have found the MPFL to be a double-bundle structure. We carried out a meta-analysis of studies reporting outcomes of patellofemoral reconstruction using hamstring tendon autograft in a double-bundle configuration and patellar fixation via mediolateral patellar tunnels. A literature search was undertaken with no language restriction in various databases from their year of inception to July 2012. The primary outcome examined was the post-operative Kujala score. We identified 320 MPFL reconstructions in nine relevant articles. The combined mean post-operative Kujala score was 92.02 (standard error (se) 1.4, p = 0.001) using a fixed effects model and 89.45 (se 37.9, p = 0.02) using random effect modelling. The reported rate of complications with MPFL reconstruction was 12.5% (40 of 320) with stiffness of the knee being the most common. High-quality evidence in assessing double-bundle MPFL reconstruction is lacking. The current literature consists of a mixture of prospective and retrospective case series. High-quality randomised trials evaluating this procedure are still awaited.

Anatomical two-bundle medial patellofemoral ligament reconstruction with hardware-free patellar graft fixation: technical note and preliminary results

PURPOSE

Various techniques for reconstruction of the medial patellofemoral ligament (MPFL) have been developed. In this article, a modified technique for anatomical two-bundle MPFL reconstruction with hardware-free patellar graft fixation is described and the preliminary results of this technique are presented.

METHODS

A modified surgical technique for MPFL reconstruction with a gracilis tendon autograft and hardware-free patellar graft fixation using two short oblique bone tunnels is described in detail. Complications and preliminary results of this procedure were assessed in 19 patients at a mean follow-up of 16 ± 3 months using the Kujala score, Tegner scale, and Insall score.

RESULTS

No postoperative patellar dislocation or subluxation was reported. Eighty-nine per cent of the patients were either satisfied or very satisfied with the overall outcome. The mean Kujala score was 92 ± 7 (range 69-100), and the median Tegner scale was 5 (range 3-7). According to the Insall score, the results of 18 patients (95%) were rated as good or excellent. Postoperative complications occurred in 3 patients (16%), with two of them persisting only temporary.

CONCLUSIONS

The described technique for anatomical two-bundle MPFL reconstruction is a safe and effective surgical procedure for the treatment of lateral patellar instability, with several methodical advantages compared to similar techniques. Further evaluation in a larger patient cohort with a longer follow-up is necessary to confirm these short-term results.

LEVEL OF EVIDENCE

IV.

Are the tubular grafts in the femoral tunnel in an anatomical or isometric position in the reconstruction of medial patellofemoral ligament?

PURPOSE

The purpose of this study was to evaluate the biomechanical results from the in vitro reconstruction of medial patellofemoral ligament (MPFL) using a navigation-assisted technique on a cadaveric model and its effects on patellar stability and kinematics. The authors investigated the hypothesis that patellar kinematics after reconstruction with a tubular graft are not optimal when compared with the original fan-shaped MPFL.

METHODS

In six fresh-frozen cadaveric knees, lateral loads (25 N) were applied on the patella at 0°, 30°, 60° and 90° of knee flexion in three different MPFL states: intact, cut and reconstructed. The arrangement allowed positional measurements of patellar motion to be tracked in six degrees of freedom. Medial to lateral patellar translation and patellar tilt were recorded. The kinematics after a technique of MPFL reconstruction, performed with a gracilis tendon in a blind femoral tunnel guided by navigation, were compared against kinematics recorded in the MPFL intact state. A temporary fixation of adequate tension to engage the lateral patellar facet in extension was applied to the MPFL and, after graft cycling, the final fixation was done at 70° knee flexion with an interference screw.

RESULTS

There was a comparable medial to lateral patellar translation and tilting of the patella in the MPFL-intact and the MPFL-reconstructed state. Static patellar translation in the MPFL-reconstructed state, with and without the application of load, was comparable to patellar translation in the MPFL-intact state. The dynamic patellofemoral shift kinematics recorded an under-constraint in early flexion and over-constraint in late flexion, while an opposite effect was recorded in patellar tilt. However, these differences were not statistically significant.

CONCLUSION

The study confirmed the major role of the MPFL in case of medial loading between 0° and 60°, by focusing on the importance of kinematically identifying the proper femoral point for fixation. While the study demonstrates the importance of kinematic determination of the proper femoral point of fixation, as the anatomical insertion remains difficult to identify. Even in dissected cadavers, the authors recorded a slightly anterior placement than native MPFL. After reconstruction, patellar stability in terms of lateral translation and tilt was similar to the intact MPFL, but patellar kinematics were not optimal with the use of a smaller and tubular graft than the native wider and fan-shaped MPFL.

Comparison of 2 different techniques for anatomic reconstruction of the medial patellofemoral ligament: a prospective randomized study

BACKGROUND

The comparative clinical outcome of anatomic reconstruction of the medial patellofemoral ligament (MPFL) between the Y-graft technique and C-graft technique for chronic patellar instability is unknown.

HYPOTHESIS

Anatomic reconstruction of the MPFL with a Y-graft technique (a Y-shaped graft: femoral fixation first with separate tensioning of the 2 bundles) would yield better clinical results than a C-graft procedure (a C-shaped graft: patellar fixation first with simultaneous tensioning of both bundles) for chronic patellar instability.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Ninety patients with symptomatic chronic patellar dislocations or instability were randomly divided into 2 groups to undergo double-bundle MPFL reconstruction either with the Y-graft technique or C-graft technique. Follow-ups were performed at 3, 6, 12, and 24 months postoperatively. The patellar stability was evaluated with the apprehension test at follow-up. The patellofemoral morphological characteristics were evaluated on axial computed tomography (CT) scans at 30° of knee flexion, and knee function was evaluated using the Lysholm and Kujala scores preoperatively and at 24 months postoperatively.

RESULTS

Forty patients in the Y-graft group and 42 patients in the C-graft group were followed for 24 months. No recurrent dislocation or subluxation was reported in either group. On CT scans, congruence angle, patellar tilt angle, lateral patellar angle, and lateral displacement were restored to the normal range. The mean postoperative Lysholm scores for the Y-graft group and C-graft group were 92.3 ± 3.9 and 88.4 ± 6.8, respectively (P = .001). The mean postoperative Kujala scores were 95.9 ± 4.7 and 91.3 ± 9.7 for the Y-graft group and C-graft group, respectively (P = .001), with a good or excellent rate of 97.5% in the Y-graft group compared with 83.3% in the C-graft group (P = .031).

CONCLUSION

With no patellar redislocations reported, the Y-graft technique for the double-bundle anatomic MPFL reconstruction achieved statistically better knee function than the C-graft procedure at a minimum 2-year follow-up. However, the increase was less than the minimal clinically important difference, and further research is required to demonstrate its meaningful clinical improvement.

Medial patellofemoral ligament reconstruction: the superficial quad technique

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is a routine procedure for patellar instability. The majority of the techniques require hardware fixation or a bony procedure at the patella. However, most of the complications described in the literature can be attributed to patellar fixation. The "superficial quad technique" uses the superficial slip of the quadriceps tendon as the graft material, which provides a better anatomic match to the native MPFL.

HYPOTHESIS

The superficial quad technique provides anatomic patellar fixation without a bony procedure and without patellar complications.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The study included 32 patients (10 male, 22 female; mean age, 25 years) who underwent MPFL reconstruction using the superficial quad technique and who were followed for a mean duration of 38 months. Objective assessment was performed and Kujala scores were obtained preoperatively and at the time of final follow-up.

RESULTS

There were no patellar complications, including redislocation, in the present study. The mean Kujala score improved to 91.25 (range, 73-100) from a preoperative score of 49.31 (range, 23-62).

CONCLUSION

The results were comparable with those of other studies in the literature that used hamstring grafts, but without associated patellar complications. The superficial quad technique uses graft material that is a better anatomic match to the native MPFL. It provides anatomic patellar fixation without a bony procedure.

Medial patellofemoral ligament reconstruction: fixation strength of 5 different techniques for graft fixation at the patella

PURPOSE

To compare the structural properties of 5 different fixation strategies for a free tendon graft at the patella in medial patellofemoral ligament (MPFL) reconstruction under cyclic loading and load to failure testing.

METHODS

We used porcine patella and flexor tendons. We tested the following fixation techniques: 3.5-mm titanium anchor, transosseous 1-mm braided polyester suture, interference screw fixation, medial bone bridge, and transpatellar tunnels. We preconditioned each graft between 5 and 20 Nm before cyclic loading with 100 Nm for 1,000 cycles was started, and then performed load to failure testing. We recorded maximum load, stiffness, and elongation.

RESULTS

In the bone bridge group, 60% of all specimens failed during cyclic testing. Fixation by transosseous sutures showed significantly less stiffness compared with all other techniques (P < .05). The bone bridge technique showed significantly lower load to failure compared with all other techniques (P < .05). Differences between the other groups were not significant.

CONCLUSIONS

Fixation of a free tendon graft by transosseous sutures provides similar load to failure and elongation but less stiffness compared with fixation by anchors, interference screws, or transverse tunnels. Load to failure for the bone bridge technique was significantly lower than that for all other techniques. Furthermore, this fixation technique had a lower load to failure than that of the native MPFL.

CLINICAL RELEVANCE

Fixation of soft tissue grafts at the patella by 1-mm braided polyester suture provides adequate fixation strength without implants in the patella, which might cause soft tissue irritation. Further studies will have to show if the lesser stiffness of this technique causes problems in the clinical setting or if this laxity might even be an advantage because it makes this reconstruction more forgiving concerning overtensioning the graft. Significantly lower load to failure of the bone bridge technique should be considered in postoperative treatment.