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

Abstract

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.

Keywords

medial patellofemoral ligament reconstruction instability stiffness femoral fixation

Medial patellofemoral ligament (MPFL) reconstruction has gained popularity since the 1990s, and much evidence exists showing a low reoperation rate, a high rate of return to sport, and reduction of apprehension and instability recurrence.^9,37 Despite overall success with MPFL reconstruction, a complication rate of up to 26% has been reported.^29,40 Complications are in part associated with difficulty in consistently finding the appropriate femoral graft insertion point. Incorrect graft placement has been implicated in failure to correct patellar instability,^4,7,29,47,48 and an anteriorly placed graft has been identified as a risk factor for postoperative stiffness due to nonisometry.²⁹ Graft placement on the femoral side has been shown to be the most influential technical factor in creating an isometric graft.⁴⁶ The proximal-distal direction has the greatest sensitivity to changes in graft length,⁴³ with an anterior position causing the greatest graft length change at deeper flexion angles.³⁵ Thus, it has been suggested to avoid a graft position that is too far anterior and proximal.¹⁷

The femoral attachment of the MPFL is located transversely in a bony groove between the medial epicondyle and the adductor tubercle.²⁶ Nomura et al found that the MPFL courses from the medial patellar margin to the posteromedial capsule, with deep fibers anchored on the femur just distal to the adductor tubercle. This is known as the “Nomura point” and is located 9.5 mm proximal and 5.0 mm posterior to the center of the medial epicondyle.²⁶

The femoral insertion of the MPFL may be located intraoperatively utilizing either open or radiographic techniques. Schöttle et al³⁸ described the widely used radiographic landmarks for anatomic femoral attachment. The Schöttle point can be localized on a true lateral radiograph 1 mm anterior to the tangent of the posterior femoral cortex, 2.5 mm distal to a perpendicular line through the proximal-most aspect of the femoral condyle, and proximal to a perpendicular line traced through the most posterior aspect of the Blumensaat line.

There are several challenges with radiographic and open approaches. It can be difficult to obtain a true lateral radiograph of the knee while instrumenting (utilizing procedural tools, inserting grafts or implants to perform the MPFL reconstruction procedure), and recently, the accuracy of the Schöttle point to the native MPFL femoral attachment has been challenged.^36,53 An open approach may theoretically provide visual or palpable confirmation of the location of the MPFL origin. However, an open approach generally requires a larger dissection, and appropriate landmarks may still be difficult to see or palpate. To our knowledge, a clinical comparison of outcomes between open and fluoroscopic techniques has not been performed.

The purpose of this systematic review was to compare clinical outcomes, particularly recurrent instability and stiffness, using a fluoroscopic versus open technique to localize the site of femoral graft attachment. We hypothesized that there would be no difference in clinical outcomes and complication rates for fluoroscopic versus open localization techniques.

Methods

Literature Search and Study Selection

A systematic review of the literature focusing on fluoroscopic and open techniques for localizing the site of femoral fixation in patients undergoing MPFL reconstruction was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.²⁴ A search was performed using PubMed, Embase, and CINAHL to identify articles published between the inception of these databases and March 1, 2022. The search terms included (“medial patellofemoral” OR “MPFL”) AND “reconstruction” OR (“patellar instability” AND “surgery”).

Inclusion criteria were a minimum 2-year follow-up as well as complete reporting of patient-reported outcomes, range of motion, stability, success/failure, and/or complications (ie, recurrent instability, stiffness, infection, persistent pain). We excluded studies of patients with Marfan, Ehlers-Danlos, or other collagen disorders; revision surgeries; surgeries with concomitant procedures; synthetic MPFL reconstruction; MPFL repairs; no description of surgical technique; combined open and radiographic technique; data not stratified by type of treatment; no femoral fixation; and <2 years of follow-up. We also excluded case series (<10 patients), review articles, abstracts, and articles not published in the English language. Two authors (K.H., C.C.) independently screened the results of the literature search to identify articles that met the inclusion criteria, which were then reviewed by the senior authors to resolve any disagreement.

Level of Evidence and Quality Assessment

We used the Oxford Centre for Evidence-Based Medicine criteria²⁷ to determine the level of evidence for each study. The same two authors independently evaluated the methodological quality and risk of bias for each study with the Downs and Black study quality assessment tool.⁶ The maximum Downs and Black score, indicative of good methodological quality/low risk for bias, is 9 points for case series, 15 points for observational studies, and 32 points for randomized controlled trials.

Data Extraction

Two reviewers (K.H., C.C.) independently extracted the following data from each article into a standardized database: study design, sample size, sex, age at surgery, length of follow-up, surgical technique (fluoroscopic or open), graft fixation method, graft origin, type of graft (autograft or allograft), and concomitant procedures. Postoperative data included apprehension, subjective instability, objective instability, recurrent dislocation, arthrofibrosis, and reoperation. Subjective instability was defined as a patient-perceived instability of the patellofemoral joint without documented dislocation. Objective instability was defined as patellar hypermobility on surgeon-performed postoperative physical examination.

Statistical Analysis

Study characteristics were tabulated and described. Since the majority of the studies were only single-arm studies, a traditional comparative meta-analysis could not be performed.⁵ Instead, 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). To include studies with zero incidences, a continuity correction was performed by adding 0.5 to the numerator and denominator of incidence.³⁴ Forest plots were made, and the pooled estimate of incidence was compared between surgical techniques by seeing if their 95% CIs overlapped. Additionally, a P value was calculated using methods described in the Cochrane handbook,¹⁶ which calculates the standard deviation from the confidence interval and uses a t test to compare means. Of note, this is an estimated P value since it was calculated using transformed values. Heterogeneity statistics (I ²) were calculated but are irrelevant to compare in proportional meta-analyses, as all studies were single-arm studies.²³ A P value <.05 was considered statistically significant, and all analyses were performed using JBI System for the Unified Management, Assessment and Review of Information.³¹

Results

The literature search identified 4183 unique articles. Of these, 240 articles were screened for eligibility and 29 met inclusion criteria (Figure 1).

Figure 1.

PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart for study inclusion. MPFL, medial patellofemoral ligament.

Study Characteristics

The characteristics of the included studies are shown in Table 1. Fifteen studies^§ (566 patients) used the open technique and 14 studies^∥ (620 patients) used fluoroscopy. There were 23 studies^¶ with level 4 evidence, 3 studies^18,32,41 with level 3 evidence, 2 studies^2,52 with level 2 evidence, and 1 study⁸ with level 1 evidence. Overall, the study quality was good, and most studies had a low risk for bias based on the total Downs and Black scores (Table 1). The minimum score indicative of good methodological quality/low risk of bias was 6 and higher for case series, 11 and higher for observational/cohorts, and 20 and higher for RCTs.

Table 1

Study Characteristics Stratified by Surgical Technique ^a

First Author (Year)	Study Design	LOE	Sample Size	Sex, M:F, n	Age at Surgery, y, mean ± SD	Length of Follow-up, mean (range)	Downs and Black Score ^b
Open Surgery Studies (n = 15)
Steiner (2006)⁴⁵	Case series	4	34	12:22	31 ± NR	66.5 mo (24-130 mo)	8
Gonçaives (2011)¹³	Case series	4	23	8:14	28.6 ± NR	26.2 mo (24-32 mo)	7
Han (2011)¹⁴	Case series	4	52 (59 knees)	19:33	24.3 ± NR	5.7 y (3.1-7.1 y)	7
Raghuveer (2012)³³	Case series	4	12 (15 knees)	4:8	29.2 ± NR	42 mo (24-60 mo)	5
Wang (2012)⁵⁰	Case series	4	21 (22 knees)	6:15	23 ± NR	37.5 mo (24-56 mo)	7
Li (2014)²⁰	Case series	4	65	28:37	29.4 ± 5.6	78.5 mo (NR)	8
Kita (2015)¹⁸	Case-control	3	42 (44 knees; 34 without PF instability, 10 with PF instability)	9:35	25.35 ± 8.7	3.2 y (2-9 y)	12
Ambrožič (2016)¹	Case series	4	29 (31 knees)	15:14	26.2 ± 6.4	6.4 y (4.2-8.5 y)	8
Niu (2017)²⁵	Case series	4	30	10:20	25.0 ± 6.9	55.1 mo (48-63 mo)	8
Tscholl (2018)⁴⁸	Case series	4	60 (63 knees)	11:49	23.7 ± 7.5	5.7 y (2y-NR)	8
Pandey (2019)²⁸	Case series	4	30	11:19	24.8 ± NR	42 mo (24-96 mo)	7
Fujii (2021)¹⁰	Case series	4	24 (27 knees)	6:18	Median: 23.9 ± 9.4	75 mo (36-129 mo)	8
Gao (2020)¹¹	Case series	4	66 (80 knees)	17:49	21.3 ± 7.8	66.1 mo (60-78 mo)	8
Marot (2021)²¹	Case-control	4	57 (29 quasi-anatomical technique; 28 anatomical MPFL reconstruction)	20:37	23.7 ± NR	NR (2-5 y)	12
Lee (2022)¹⁹	Case Series	4	21	Not Specified	25.1 ± NR	3.45 y (2-5 y)	8
Fluoroscopy Studies (n = 14)
Witoński (2013)⁵¹	Case series	4	10	NR	27.2 ± 8.1	43 mo (48-55 mo)	7
Song (2014)⁴⁴	Case series	4	20	10:10	Median: 21 ± NR	Median: 34.5 mo (24-50 mo)	8
Astur (2015)²	RCT	2	58 (30 graft Endobutton fixation; 28 graft fixation)	30:28	29.81 ± NR	NR (2-5 y)	11
Vavalle (2016)⁴⁹	Case series	4	16	9:7	22 ± NR	38 mo (28-48 mo)	7
Sim (2018)⁴²	Case series	4	11 (12 knees)	5:6	18.6 ± 4.4	Median: 28.8 mo (24-48 mo)	8
Peter (2019)³⁰	Case series	4	36 (38 knees)	17:19	25.1 ± 6.1	24 mo (NR)	9
Puzzitiello (2019)³²	Cohort study	3	51 (32 reconstruction; 19 imbrication and/or repair)	23:28	22.8 ± 9.25	59.7 mo (24-121 mo)	12
Blanke (2020)³	Case series	4	52	29:23	26 ± 4.2	NR (24-36 mo)	8
Mayer (2020)²²	Case series	4	128	42:62	21.9 ± 8.1	45.7 mos (41-52 mo)	7
Ye (2020)⁵²	Cohort study	2	65 (31 suture anchor fixation at patella; n = 34 transosseous suture anchor fixation)	28:37	28.53 ± 5.85	44.07 mo (NR)	11
Zhang (2020)⁵³	Case series	4	29	8:21	27.35 ± 5.81	37.52 mo (26-48 mo)	8
Shih (2022)⁴¹	Cohort Study	3	33	30:3	21.5 ± NR	43 mo (24-96 mo)	13
Giesler (2022)¹²	Case Series	4	31	14:17	22 ± 6	24 mo (NR)	9
Ercan (2021)⁸	RCT	1	80	38:42	17 ± NR	43.3 mo (24-74 mo)	24

^a F, female; LOE, level of evidence; M, male; MPFL, medial patellofemoral ligament; NR, not reported; PF, patellofemoral; RCT, randomized controlled trial.

^b The maximum possible Downs and Black score, indicative of good methodological quality/low risk for bias, is 9 points for case series, 15 points for observational studies, and 32 points for randomized controlled trials.

Suture anchor or transosseous suture^＃ were most commonly used for graft fixation to the patella, and an interference screw was most commonly used for femoral fixation. ^** Most studies used semitendinosus or gracilis hamstring autograft for MPFL reconstruction (Table 2).

Table 2

Surgical Details Stratified by Surgical Technique ^a

First Author (Year)	Graft Fixation	Graft Origin	Type of Graft	Concomitant Procedures
Open Surgery Studies (n = 15)
Steiner (2006)⁴⁵	Suture fixation and lag screw for the bone block grafts	Adductor or bone-quad/bone-patellar tendon bone	Autograft	None reported
Gonçaives (2011)¹³	Interference screw	ST	Autograft	None reported
Han (2011)¹⁴	Interference screw	ST (n = 44), gracilis (n = 8)	Autograft	Chondral debridement, removal of loose bodies, lateral release
Raghuveer (2012)³³	Bone anchor (n = 4), bioresorbable screw (n = 11)	Gracilis (n = 4), ST (n = 8)	Autograft	Lateral release (n = 2)
Wang (2012)⁵⁰	Suture fixation to the patella and bioabsorbable interference screw	ST	Autograft	Lateral retinacular release
Li (2014)²⁰	Combination of bone-fascia suture tunnel and interference screw	TA	Allograft	None reported
Kita (2015)¹⁸	Endobutton on femur and patella	ST	Autograft	Loose body removed (n = 8)
Ambrožič (2016)¹	Biosuture anchors in the patella and absorbable interference screw	Gracilis	Autograft	None reported
Niu (2017)²⁵	Bioresorbable interference screw and suture fixation	ST	Autograft	None reported
Tscholl (2018)⁴⁸	Not specified	Gracilis	Autograft	None reported
Pandey (2019)²⁸	Bioresorbable interference screw	ST	Autograft	Loose body removal
Fujii (2021)¹⁰	Endobutton for patella and tenodesis screw/Endobutton for femur	ST	Autograft	None reported
Gao (2020)¹¹	Bioresorbable interference screw	Gracilis	Autograft	Loose body removal, chondroplasty, synovitis
Marot (2021)²¹	▪ Group A: quasi-anatomic suture fixation ▪ Group B: anatomic suture anchor fixation	▪ Group A: gracilis ▪ Group B: ST	Autograft	None reported
Lee (2022)¹⁹	Suture anchor in patella and interference screw on femur	ST and TA	Autograft or allograft	Lateral release
Fluoroscopy Studies (n = 14)
Witoński (2013)⁵¹	Titanium suture anchor	Patellar tendon	Autograft	None reported
Song (2014)⁴⁴	Suture anchor in patella and bioabsorbable screw	ST (n = 8), gracilis (n = 2)	Autograft	Lateral release (n = 3), Chondroplasty (n = 5)
Astur (2015)²	▪ Group 1: Endobutton and interference screw ▪ Group 2: patellar anchor and interference screw	Gracilis	Autograft	None reported
Vavalle (2016)⁴⁹	Suture anchors (+ transosseous sutures, n = 6)	Quad	Autograft	Lateral release
Sim (2018)⁴²	Suture anchors in the patella and button	ST	Autograft	Lateral release
Blanke (2019)³	Not specified	Gracilis	Autograft	Lateral release
Mayer (2020)²²	Interference screw	Gracilis	Autograft	None reported
Peter (2019)³⁰	Bioresorbable interference screw	Partial-thickness quad	Autograft	None reported
Puzzitiello (2019)³²	Biotenodesis screw in femur and suture anchors in patella	Hamstring and TA	Allograft (hamstring and TA) and autograft (hamstring)	31.3% of the reconstruction group received lateral release
Ye (2020)⁵²	▪ Group 1: transosseous sutures and bioabsorbable interference screw ▪ Group 2: suture anchors and bioabsorbable interference screw	Gracilis	Autograft	Lateral retinacular release (n = 8 in suture anchor, n = 9 in transosseous suture)
Zhang (2020)⁵³	Transosseous suture fixation with bioabsorbable interference screw	Gracilis	Autograft	Lateral release
Shih (2022)⁴¹	Suture anchors on the patella and interference screw on the femur	ST	Autograft	None reported
Giesler (2022)¹²	2 bioresorbable anchors at patella and interference screw at femur	Gracilis	Autograft	None reported
Ercan (2021)⁸	Transosseous suture fixation with bioabsorbable interference screw	ST	Autograft	None reported

^a Quad, quadriceps tendon; ST, semitendinosus; TA, tibialis anterior.

Results of Meta-analysis

The incidence rates of postoperative apprehension after fluoroscopic (3.1% [95% CI, 0.0%-9.1%]) and open (5.4% [95% CI, 2.6%-8.8%]) techniques were not significantly different (P = .4826) (Figure 2). In addition, there was no significant difference in the incidence of postoperative subjective instability for fluoroscopic (3.1% [95% CI, 1.3%-5.6%]) versus open (6.1% [95% CI, 3.3%-9.5%]) techniques (P = .1095) (Figure 3). The incidence of reoperation for the fluoroscopic (3.2% [95% CI, 1.3%-5.7%]) compared with the open (3.6% [95% CI, 1.8%-6.0%]) technique was not significantly different (P = .7981) (Figure 4).

Figure 2.

Forest plot illustrating the prevalence of postoperative apprehension for (A) intraoperative fluoroscopy versus (B) open surgery.

Figure 3.

Forest plot illustrating the prevalence of postoperative subjective instability for (A) intraoperative fluoroscopy versus (B) open surgery.

Figure 4.

Forest plot illustrating the prevalence of reoperation for (A) intraoperative fluoroscopy versus (B) open surgery.

There was no significant difference in the incidence of postoperative objective instability after the fluoroscopic (1.4% [95% CI, 0.1%-3.7%]) versus the open (2.5% [95% CI, 0.1%-7.1%]) technique (P = .5583) (Figure 5). The incidence rates of recurrent dislocation after fluoroscopic (1.4% [95% CI, 0.4%-2.8%]) and open (1.8% [95% CI, 0.6%-3.4%]) techniques were not significantly different (P = .6690) (Figure 6). Last, there was no significant difference in the incidence of arthrofibrosis for the fluoroscopic (1.7% [95% CI, 0.1%-4.6%]) compared with the open (1.3% [95% CI, 0.0%-4.7%]) technique (P = .8118) (Figure 7).

Figure 5.

Forest plot illustrating the prevalence of postoperative objective instability for (A) intraoperative fluoroscopy versus (B) open surgery. F-T.

Figure 6.

Forest plot illustrating the prevalence of recurrent dislocation for (A) intraoperative fluoroscopy versus (B) open surgery.

Figure 7.

Forest plot illustrating the prevalence of arthrofibrosis for (A) intraoperative fluoroscopy versus (B) open surgery.

Discussion

Our proportional meta-analysis comparing the pooled incidence of complications revealed no significant differences in postoperative outcomes when comparing open and radiographic techniques to localize femoral tunnel position during MPFL reconstruction. The incidence rates of postoperative apprehension (fluoroscopic, 3.1%; open, 5.4%), subjective instability (fluoroscopic, 3.1%; open, 6.1%), reoperation (fluoroscopic, 3.2%; open, 3.6%), objective instability (fluoroscopic, 1.4%; open, 2.5%), recurrent dislocation (fluoroscopic, 1.4%; open 1.8%), and arthrofibrosis (fluoroscopic, 1.7%; open, 1.3%) were not statistically different. Reoperations were reported for 11 of 317 patients in the fluoroscopy group and 19 of 400 in the open technique group. Reoperations were required for removal of symptomatic hardware, arthrofibrosis, redislocation, graft failure, patellar fracture, postoperative hematoma, and suture granuloma.^††

Complications after MPFL reconstruction may be due to several different anatomical or surgical factors. One potential source of complications may be poor femoral tunnel placement.^4,29,40 Some studies have evaluated how accurate surgeons are at determining the location of femoral fixation.^48,54 Additionally, the accuracy of the radiographic technique utilizing the Schöttle point has recently been called into question. Sanchis-Alfonso et al³⁵ showed that the native attachment of the MPFL may be up to 4.1 mm from the radiographic point as identified. Furthermore, the margin of error for localizing the Schöttle point on a lateral radiograph is quite small. Five degrees of rotational error corresponds to malpositions of 7.5, 9.2, and 8.1 mm in the anteroposterior, posteroanterior, and cephalad orientations, respectively.⁵⁴ By comparison, the open technique has demonstrated a broad range of accuracy, from 65% to 92.3%.^15,39 Despite these findings, our data suggest that the outcomes and complication profile are similar for both techniques.

Limitations

Our study has several limitations inherent to being a proportional meta-analysis, including the lack of comparative arms within studies, publication bias, small study effect, and the quality and heterogeneity of the studies included. Most of the studies included had a low level of evidence. Variabilities in patient number, sex ratio, age at time of surgery, and length of follow-up can also be seen. Another limitation in this study is the variation in technique and implant choice. However, we did find that most studies used suture anchor or transosseous suture for patellar fixation, and more than two-thirds used interference screw femoral fixation (24/29 studies). It also should be noted that failure of fixation is a rare complication and was not reported in any of the included studies, making it unlikely that implant differences were an important factor. Finally, the largest limitation may be that the primary purpose of the included studies was to report results rather than complications, which could have caused underreporting of stiffness, in particular.

Conclusion

The study findings suggest that both open and radiographic localization of femoral graft position in MPFL reconstruction offer similar outcomes. We found no significant differences in the rates of postoperative apprehension, postoperative subjective instability, postoperative objective instability, reoperations, recurrent dislocation, or arthrofibrosis when comparing open and fluoroscopic techniques. Surgeons can choose either technique and expect similar results.

Footnotes

Notes

Final revision submitted September 30, 2022; accepted October 21, 2022.

One or more of the authors has declared the following potential conflict of interest or source of funding: K.H. has received grant support from Arthrex; education payments from Arthrex, Smith & Nephew, and Rock Med; and hospitality payments from Zimmer Biomet. C.C. has received grant support from Arthrex and education payments from Arthrex and Smith & Nephew. B.J.L. has received education payments from Prodigy Surgical. L.B. has received royalties from Zimmer Biomet and hospitality payments from Arthrex and Prodigy Surgical. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

References

Ambrožič

Novak

. The influence of medial patellofemoral ligament reconstruction on clinical results and sports activity level. Phys Sportsmed. 2016;44(2):133–140.

Astur

Gouveia

Borges

JHS

, et al. Medial patellofemoral ligament reconstruction: a longitudinal study comparison of 2 techniques with 2 and 5-years follow-up. Open Orthop J. 2015;9(1):198–203.

Blanke

Watermann

Haenle

Feitenhansl

Camathias

Vogt

. Isolated medial patellofemoral ligament reconstruction can be an effective procedure in patellofemoral instability with risk factors. J Knee Surg. 2020;33(10):992–997.

Bollier

Fulkerson

Cosgarea

Tanaka

. Technical failure of medial patellofemoral ligament reconstruction. Arthroscopy. 2011;27(8):1153–1159.

Conn

Ruppar

Phillips

Chase

. Using meta-analyses for comparative effectiveness research. Nurs Outlook. 2012;60(4):182–190.

Downs

Black

. The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health. 1998;52(6):377–384.

Elias

Cosgarea

. Technical errors during medial patellofemoral ligament reconstruction could overload medial patellofemoral cartilage: a computational analysis. Am J Sports Med. 2006;34(9):1478–1485.

Ercan

Akmese

Ulusoy

. Single-tunnel and double-tunnel medial patellofemoral ligament reconstructions have similar clinical, radiological and functional results. Knee Surg Sports Traumatol Arthrosc. 2021;29(6):1904–1912.

Erickson

Mascarenhas

Sayegh

, et al. Does operative treatment of first-time patellar dislocations lead to increased patellofemoral stability? A systematic review of overlapping meta-analyses. Arthroscopy. 2015;31(6):1207–1215.

10.

Fujii

Nakagawa

Arai

, et al. Clinical outcomes after medial patellofemoral ligament reconstruction: an analysis of changes in the patellofemoral joint alignment. Int Orthop. 2021;45(5):1215–1222.

11.

Gao

Liu

. Treatment of patellar dislocation with arthroscopic medial patellofemoral ligament reconstruction using gracilis tendon autograft and modified double-patellar tunnel technique: minimum 5-year patient-reported outcomes. J Orthop Surg Res. 2020;15(1):25.

12.

Giesler

Baumann

Weidlich

, et al. Patellar instability MRI measurements are associated with knee joint degeneration after reconstruction of the medial patellofemoral ligament. Skeletal Radiol. 2022;51(3):535–547.

13.

Gonçaives

MBJ

de Carvalho Júnior

Soares

LFM

Gonçaives

Dos Santos

Pereira

. Medial patellofemoral ligament reconstruction to treat recurrent patellar dislocation. Rev Bras Ortop. 2011;46(2):160–164.

14.

Han

Xia

Yun

. Anatomical transverse patella double tunnel reconstruction of medial patellofemoral ligament with a hamstring tendon autograft for recurrent patellar dislocation. Arch Orthop Trauma Surg. 2011;131(3):343–351.

15.

Hiemstra

O’Brien

Lafave

Kerslake

. Accuracy and learning curve of femoral tunnel placement in medial patellofemoral ligament reconstruction. J Knee Surg. 2017;30(09):879–886.

16.

Higgins

JPT

Deeks

, eds. Chapter 6: choosing effect measures and computing estimates of effect. In: Higgins

JPT

Thomas

Chandler

, et al. eds. Cochrane Handbook for Systematic Reviews of Interventions. Version 6.3. 2022. Accessed December 28, 2022. https://training.cochrane.org/handbook/

17.

Kernkamp

Wang

, et al. The medial patellofemoral ligament is a dynamic and anisometric structure: an in vivo study on length changes and isometry. Am J Sports Med. 2019;47(7):1645–1653.

18.

Kita

Tanaka

Toritsuka

, et al. Factors affecting the outcomes of double-bundle medial patellofemoral ligament reconstruction for recurrent patellar dislocations evaluated by multivariate analysis. Am J Sports Med. 2015;43(12):2988–2996.

19.

Lee

Jaffar

MSA

Choi

Kim

Lee

. Effect of isolated medial patellofemoral ligament reconstruction in patellofemoral instability regardless of predisposing factors. J Knee Surg. 2022;35(3):299–307.

20.

Wei

Wang

Gao

Shen

. A simple technique for reconstruction of medial patellofemoral ligament with bone-fascia tunnel fixation at the medial margin of the patella: a 6-year-minimum follow-up study. J Orthop Surg Res. 2014;9(1):66.

21.

Marot

Sanchis-Alfonso

Perelli

, et al. Isolated reconstruction of medial patellofemoral ligament with an elastic femoral fixation leads to excellent clinical results. Knee Surg Sports Traumatol Arthrosc. 2021;29(3):800–805.

22.

Mayer

Schuster

Schlumberger

, et al. Midterm results after implant-free patellar fixation technique for medial patellofemoral ligament reconstruction. J Knee Surg. 2020;33(11):1140–1146.

23.

Migliavaca

Stein

Colpani

; et al. Prevalence Estimates Reviews-Systematic Review Methodology Group (PERSyst). Meta-analysis of prevalence: I ² statistic and how to deal with heterogeneity. Res Synth Methods. 2022;13(3):363–367.

24.

Moher

Liberati

Tetzlaff

Altman

; PRISMA Group. Preferred Reporting Items for Systematic Reviews and Meta-Analyses: the PRISMA statement. PLoS Med. 2009;6(7):e1000097.

25.

Niu

Duan

Liu

Wang

. Medial patellofemoral ligament reconstruction with semi-patellar tunnel fixation: surgical technique and mid-term follow-up. Med Sci Monit. 2017;23:5870–5875.

26.

Nomura

Inoue

Osada

. Anatomical analysis of the medial patellofemoral ligament of the knee, especially the femoral attachment. Knee Surg Sports Traumatol Arthrosc. 2005;13(7):510–515.

27.

OCEBM Levels of Evidence Working Group. The Oxford 2011 Levels of Evidence. Oxford Centre for Evidence-Based Medicine. 2011. Accessed December 28, 2022. http://www.cebm.net/index.aspx?o=5653

28.

Pandey

Mannava

Zakhar

Mody

Acharya

. Accuracy of Schottle’s point location by palpation and its role in clinical outcome after medial patellofemoral ligament reconstruction. J Arthrosc Jt Surg. 2019;6(2):117–122.

29.

Parikh

Nathan

Wall

Eismann

. Complications of medial patellofemoral ligament reconstruction in young patients. Am J Sports Med. 2013;41(5):1030–1038.

30.

Peter

Hoser

Runer

Abermann

Wierer

Fink

. Medial patellofemoral ligament (MPFL) reconstruction using quadriceps tendon autograft provides good clinical, functional and patient-reported outcome measurements (PROM): a 2-year prospective study. Knee Surg Sports Traumatol Arthrosc. 2019;27(8):2426–2432.

31.

Piper

System for the Unified Management, Assessment, and Review of Information (SUMARI). J Med Libr Assoc. 2019;107(4):634–636.

32.

Puzzitiello

Waterman

Agarwalla

, et al. Primary medial patellofemoral ligament repair versus reconstruction: rates and risk factors for instability recurrence in a young, active patient population. Arthroscopy. 2019;35(10):2909–2915.

33.

Raghuveer

Mishra

. Reconstruction of medial patellofemoral ligament for chronic patellar instability. Indian J Orthop. 2012;46(4):447–454.

34.

Ross

Distributions of sampling statistics. In:Introduction to Probability and Statistics for Engineers and Scientists. 5th ed. Academic Press; 2014:218–219.

35.

Sanchis-Alfonso

Ramirez-Fuentes

Montesinos-Berry

Domenech

Martí-Bonmatí

. Femoral insertion site of the graft used to replace the medial patellofemoral ligament influences the ligament dynamic changes during knee flexion and the clinical outcome. Knee Surg Sports Traumatol Arthrosc. 2017;25(8):2433–2441.

36.

Sanchis-Alfonso

Ramírez-Fuentes

Montesinos-Berry

Elía

Martí-Bonmatí

. Radiographic location does not ensure a precise anatomic location of the femoral fixation site in medial patellofemoral ligament reconstruction. Orthop J Sports Med. 2017;5(11):2325967117739252.

37.

Schneider

Grawe

Magnussen

, et al. Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent lateral patellar dislocations: a systematic review and meta-analysis. Am J Sports Med. 2016;44(11):2993–3005.

38.

Schöttle

Schmeling

Rosentstiel

Weiler

. Radiographic landmarks for femoral tunnel placement in medial patellofemoral ligament reconstruction. Am J Sports Med. 2007;35(5):801–804.

39.

Servien

Fritsch

Lustig

, et al. In vivo positioning analysis of medial patellofemoral ligament reconstruction. Am J Sports Med. 2011;39(1):134–139.

40.

Shah

Howard

Flanigan

Brophy

Carey

Lattermann

. A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med. 2012;40(8):1916–1923.

41.

Shih

SSW

Kuo

Lee

DYH

. MPFL reconstruction corrects patella alta: a cohort study. Eur J Orthop Surg Traumatol. 2022;32(5):883–889.

42.

Sim

Lim

Lee

. Anatomic double-bundle medial patellofemoral ligament reconstruction with aperture fixation using an adjustable-length loop device: a 2-year follow-up study. BMC Musculoskelet Disord. 2018;19(1):346.

43.

Smirk

Morris

. The anatomy and reconstruction of the medial patellofemoral ligament. Knee. 2003;10(3):221–227.

44.

Song

Kim

Chang

Shin

Kim

Seo

. Anatomic medial patellofemoral ligament reconstruction using patellar suture anchor fixation for recurrent patellar instability. Knee Surg Sports Traumatol Arthrosc. 2014;22(10):2431–2437.

45.

Steiner

Torga-Spak

Teitge

. Medial patellofemoral ligament reconstruction in patients with lateral patellar instability and trochlear dysplasia. Am J Sports Med. 2006;34(8):1254–1261.

46.

Stephen

Kittl

Williams

, et al. Effect of medial patellofemoral ligament reconstruction method on patellofemoral contact pressures and kinematics. Am J Sports Med. 2016;44(5):1186–1194.

47.

Tanaka

Bollier

Andrish

Fulkerson

Cosgarea

. Complications of medial patellofemoral ligament reconstruction: common technical errors and factors for success: AAOS exhibit selection. J Bone Joint Surg Am. 2012;94(12):e87.

48.

Tscholl

Ernstbrunner

Pedrazzoli

Fucentese

. The relationship of femoral tunnel positioning in medial patellofemoral ligament reconstruction on clinical outcome and postoperative complications. Arthroscopy. 2018;34(8):2410–2416.

49.

Vavalle

Capozzi

. Isolated reconstruction of the medial patellofemoral ligament with autologous quadriceps tendon. J Orthop Traumatol. 2016;17(2):155–162.

50.

Wang

Liu

, et al. Reconstruction of the medial patellofemoral ligament with a suture-tie technique of patellar side fixation. Chin Med J (Engl). 2012;125(11):1884–1888.

51.

Witoński

Kęska

Synder

Sibiński

. An isolated medial patellofemoral ligament reconstruction with patellar tendon autograft. Biomed Res Int. 2013;2013:637678.

52.

Zhang

Liang

. Clinical outcomes after medial patellofemoral ligament reconstruction using transosseous sutures versus suture anchors: a prospective nonrandomized controlled trial. Orthop J Sports Med. 2020;8(5):2325967120917112.

53.

Zhang

Liang

. Clinical outcomes after medial patellofemoral ligament reconstruction with suture fixation of the gracilis tendon via transosseous tunnels. Orthop J Sports Med. 2020;8(2):2325967119900373.

54.

Ziegler

Fulkerson

Edgar

. Radiographic reference points are inaccurate with and without a true lateral radiograph: the importance of anatomy in medial patellofemoral ligament reconstruction. Am J Sports Med. 2016;44(1):133–142.