Femoral insertion osteotomy of the lateral collateral ligament for expanding lateral knee space in meniscus repair

Abstract

Objective

To evaluate the technical feasibility, short-term safety, and clinical outcomes of an incomplete osteotomy at the femoral insertion of the lateral collateral ligament (LCL) for expanding a tight lateral compartment during arthroscopic lateral meniscus repair.

Methods

A single-institution retrospective case series was conducted in patients with lateral meniscus tears and a tight lateral compartment who underwent LCL femoral insertion osteotomy between January 2020 and December 2022. Osteotomy was performed only when standard exposure maneuvers, including the figure-four position, portal adjustment, and gentle varus stress, failed to provide safe visualization and instrument access. The primary outcome was technical success, defined as adequate arthroscopic exposure and completion of the planned meniscal repair. Secondary outcomes included Lysholm score, International Knee Documentation Committee (IKDC) score, Visual Analog Scale (VAS) score for knee pain, osteotomy healing on computed tomography (CT), meniscal healing on magnetic resonance imaging (MRI), and complications.

Results

Twenty-five knees were included and followed for 12 months. Adequate exposure of the lateral meniscus and completion of meniscal repair were achieved in all cases. At 12 months, Lysholm, IKDC, and VAS scores improved significantly compared with preoperative values (all P < 0.001). CT at 3 months showed satisfactory osteotomy healing without displacement in all patients. MRI at 12 months demonstrated meniscal healing in 19 patients (76%); the 6 patients who did not meet MRI healing criteria were asymptomatic and did not require reoperation during follow-up. No infection, neurovascular complication, clinically apparent varus instability, loss of reduction, or serious complication was observed.

Conclusion

In selected patients with lateral meniscus tears and a tight lateral compartment, arthroscopic repair combined with incomplete osteotomy of the LCL femoral insertion may facilitate exposure and meniscal repair with satisfactory short-term functional recovery. Because this retrospective case series lacked a control group and objective quantification of joint-space widening, the findings should be confirmed in prospective comparative studies with longer follow-up.

Introduction

Meniscal tears of the knee joint are one of the most common orthopedic knee injuries, second only to anterior cruciate ligament (ACL) tears [1]. The annual incidence of meniscal tears is approximately 60 per 100,000 people [2, 3]. A 10-year follow-up study by Majewski et al. found that lateral meniscus injuries accounted for 8.2% of intra-articular knee injuries [1], and the incidence of lateral meniscus injuries has shown a continuous upward trend [4]. Arthroscopic repair of meniscal tears offers several advantages, including minimally invasive intervention, reduced hospital stay, and faster rehabilitation, making it the preferred treatment option for meniscal injuries [3]. Adequate exposure of intra-articular structures, a clear surgical field, and sufficient operating space are essential conditions for successful arthroscopic surgery [5]. However, in some patients with lateral meniscus injuries, a tight lateral joint space can result in poor visualization, inadequate assessment of meniscal injury, and difficulty in inserting arthroscopic instruments, thereby complicating the procedure.In certain cases, even placing the knee in a “figure-four” position does not provide a satisfactory surgical view due to the tight lateral knee joint space. Restricted maneuverability of arthroscopic instruments within the joint cavity makes the procedure more challenging, leading to suboptimal meniscal repair outcomes, decreased patient satisfaction, and an increased risk of iatrogenic cartilage injuries [6]. Therefore, identifying an effective method to expand the lateral knee joint space has become an urgent necessity.

The medial collateral ligament (MCL) is a broad, flat structure, and percutaneous pie-crusting release has been widely used to improve access to a tight medial compartment during arthroscopy [7–9]. In contrast, the LCL is a cord-like structure and an important restraint to varus stress; repeated puncture or uncontrolled release may increase the risk of structural injury and lateral instability [10–12]. We do not claim that osteotomy around the lateral femoral epicondyle is a completely new anatomical maneuver. Rather, the novelty of the present study is the application of a small incomplete osteotomy at the femoral insertion of the LCL specifically to obtain temporary expansion of a tight lateral compartment during arthroscopic lateral meniscus repair. The objective of this study was to evaluate the technical feasibility, short-term safety, osteotomy healing, meniscal healing, and clinical outcomes of this technique.

Materials and methods

Patient demographics

This retrospective case series was approved by the Ethics Committee of Fujian Medical University Union Hospital (Approval No. 2024KY097) and was conducted in accordance with the Declaration of Helsinki.The requirement for informed consent for study participation was waived by the Ethics Committee because of the retrospective design and use of de-identified clinical data; however, written informed consent for the surgical procedure was obtained before surgery from all patients.

Between January 2020 and December 2022, the records of patients who underwent arthroscopic treatment for lateral meniscus tears by a single senior surgeon were reviewed. The final cohort comprised all identified patients who underwent LCL femoral insertion osteotomy because adequate visualization and instrument access could not be achieved with standard exposure maneuvers. Because a prospective screening log of all lateral meniscus repairs was not created when this technique was introduced, the exact number of patients who underwent lateral meniscus repair without osteotomy could not be reliably reconstructed; this is acknowledged as a limitation of this retrospective study.

The inclusion criteria were as follows: (1) lateral meniscus tear requiring arthroscopic repair; (2) tight lateral compartment confirmed intraoperatively after standard attempts at exposure; (3) normal preoperative varus stability without high-grade LCL or posterolateral corner injury; and (4) a minimum 12-month clinical and imaging follow-up. The exclusion criteria were multiple ligament injuries, osteoarthritis, fracture around the knee, previous surgery involving the LCL femoral insertion, infection, inflammatory arthropathy, or incomplete follow-up data.

Preoperative evaluation included anteroposterior and lateral knee radiographs, varus stress radiographs, and MRI to assess meniscal tear pattern, ligament status, and degenerative change. Baseline Lysholm, IKDC, and VAS scores were recorded before surgery. The primary outcome was technical success, defined as sufficient lateral meniscus visualization and instrument maneuverability to complete the planned meniscal repair without conversion or intraoperative cartilage injury. Secondary outcomes included clinical scores, osteotomy healing, meniscal healing on MRI, and complications.

Surgical method

The patient was placed supine on the operating table. After routine disinfection and draping, standard anterolateral and anteromedial portals were created, and diagnostic arthroscopy of the affected knee was performed. Before deciding to perform osteotomy, stepwise standard maneuvers were attempted, including the figure-four position, portal adjustment, and gentle varus stress under arthroscopic visualization.

A tight lateral compartment was defined intraoperatively using a standardized functional criterion: after the above maneuvers, a meniscal probe or repair instrument could not be safely advanced to the body and posterior horn of the lateral meniscus or could not access the red-red/red-white zone without compressing the articular cartilage. A direct millimeter measurement of the lateral femorotibial gap was not recorded in this retrospective cohort; prospective studies should use a marked probe or ruler to quantify the intraoperative gap and the degree of joint-space widening.

The affected knee was flexed to 90 degrees, and the lateral femoral epicondyle corresponding to the femoral insertion of the LCL was palpated. A 3-cm longitudinal incision was made, and the soft tissue was dissected to expose the LCL femoral insertion. The osteotomy was designed to match the LCL femoral footprint, approximately 10 mm in the anteroposterior direction and 12 mm in the proximal-distal direction, based on reported anatomic dimensions10. An osteotome was used along the superior, anterior, and posterior margins of the insertion to create an incomplete osteotomy (Fig. 1). The Proximal cortical hinge was preserved during the osteotomy. A fixed osteotome depth was not used because the thickness of the lateral femoral condyle varies among patients; instead, the osteotome was advanced only until the fragment could be gently mobilized distally while maintaining a bony hinge.

Fig. 1.

Intraoperative exposure and schematic illustration of the incomplete osteotomy at the femoral insertion of the lateral collateral ligament (LCL). The patient was placed supine and the knee was flexed to 90 degrees. A gross intraoperative image with the arrow indicating the LCL femoral insertion/osteotomy site. B schematic diagram showing the incomplete osteotomy and distal mobilization of the bone fragment

Under arthroscopic monitoring, the knee was again placed in the figure-four position and gentle varus stress was applied until the body and posterior horn of the lateral meniscus were satisfactorily visualized. The repair technique was selected according to the tear pattern and device trajectory. All-inside repair was preferred when the device could be safely positioned perpendicular or oblique to the tear, whereas an inside-out or dual-needle technique was used when wider suture capture or an alternative trajectory was required (Fig. 2).

Fig. 2.

Exposure and suturing of the lateral meniscus before and after osteotomy. A and B visualization of the lateral meniscus before osteotomy; the torn lateral meniscus was not adequately exposed. C exposure of the lateral meniscus after osteotomy, showing a longitudinal tear in the meniscal body and a radial tear in the posterior horn. D and E meniscus after suturing. F lateral knee joint space after reduction and fixation of the osteotomized bone fragment

At the end of the surgery, the osteotomized bone fragment was anatomically reduced with the knee in a valgus position. Two small transosseous tunnels were drilled through the fragment using 2.0-mm Kirschner wires. Two high-strength sutures were passed through the tunnels and tied on the medial cortex to compress and stabilize the fragment [12]. Reduction was checked by direct visualization and arthroscopy, and excessive tensioning was avoided to minimize the risk of fragment fracture or overconstraint [13].

Postoperative management

After surgery, a knee hinge brace was applied without restricting knee range of motion. Once anesthesia wore off, patients immediately began ankle pump exercises and quadriceps isometric contractions of the affected limb. For the first 2–3 weeks postoperatively, patients used crutches and avoided weight-bearing on the affected knee. From postoperative weeks 3–4, partial weight-bearing was allowed, and knee range of motion exercises were increased from 0° to 120°. Between 4 and 8 weeks postoperatively, patients gradually resumed walking, and normal sports activities were resumed after 6 months. Follow-up visits were conducted at 3, 6, and 12 months postoperatively, during which relevant data were recorded.

Clinical and imaging evaluation

Clinical outcomes were assessed using the Lysholm knee scoring scale, the IKDC score, and the VAS score for knee pain. Lateral stability was evaluated by varus stress testing during physical examination at follow-up. Postoperative varus stress radiographs were not routinely obtained in this retrospective cohort; therefore, subtle side-to-side laxity could not be objectively quantified and this limitation is addressed in the Discussion.

At 3 months postoperatively, CT with three-dimensional reconstruction was performed to assess osteotomy union, displacement, or malunion. At 12 months postoperatively, MRI was used to evaluate meniscal healing. According to the MRI assessment protocol proposed by Schwach et al. [14], postoperative changes were considered consistent with healing when the following criteria were met: the signal changed from a high-intensity fluid signal to a medium-intensity non-fluid signal on fat-saturated T2-weighted imaging; the postoperative tear gap was reduced to 1.5 mm or less; and the initial tear morphology changed with low-intensity bridging and high-intensity branching. Second-look arthroscopy was not routinely performed, and interobserver reliability for MRI interpretation was not assessed in this retrospective study.

Statistical analysis

Statistical analysis was performed using SPSS software version 26. Continuous variables were assessed for normality using the Shapiro-Wilk test. Lysholm and IKDC scores measured preoperatively and at 3, 6, and 12 months postoperatively were analyzed using repeated-measures ANOVA. Mauchly’s test was used to assess sphericity; if sphericity was violated, Greenhouse-Geisser correction was applied. Pairwise comparisons were adjusted using the Bonferroni method. VAS scores were analyzed using the Friedman test, followed by Bonferroni-adjusted Wilcoxon signed-rank tests for pairwise comparisons.

Results

After applying the inclusion and exclusion criteria, 25 knees were included in the final cohort. The tear patterns included 11 radial tears of the posterior horn or body of the lateral meniscus, 7 longitudinal tears, 6 horizontal tears, and 2 posterior root tears. All patients completed 12 months of follow-up. The primary technical endpoint was achieved in all cases: after LCL femoral insertion osteotomy, the lateral meniscus could be adequately visualized and the planned repair could be completed. Surgical incisions achieved Grade A healing in all patients, and no infection, neurovascular complication, or intraoperative cartilage injury attributable to limited space was recorded.

At 3 months postoperatively, CT showed satisfactory healing of the osteotomy at the lateral femoral condyle in all 25 patients, without displacement, fracture, or malunion (Fig. 3). At 12 months, MRI indicated lateral meniscus healing in 19 patients, corresponding to a healing rate of 76%. The remaining 6 patients did not meet the predefined MRI healing criteria, but they were asymptomatic, had negative varus stress tests on physical examination, and did not require reoperation during the 12-month follow-up. No clinically apparent varus instability was observed.

Fig. 3.

Three-dimensional CT reconstruction at 3 months after surgery. The arrow indicates healing of the osteotomized bone fragment without displacement

Lysholm scores differed significantly among the preoperative and postoperative time points (P < 0.001). Bonferroni-adjusted pairwise comparisons showed no significant difference between 3 and 6 months postoperatively (P = 0.709), whereas the differences between 3 and 12 months (P = 0.010) and between 6 and 12 months (P < 0.001) were statistically significant.

IKDC scores differed significantly among the preoperative and postoperative time points (P < 0.001). Bonferroni-adjusted comparisons demonstrated significant improvements between 3 and 6 months, 3 and 12 months, and 6 and 12 months postoperatively (all P < 0.001).

VAS scores also differed significantly across the four time points (P < 0.001 by Friedman test). The comparison between 3 and 6 months postoperatively was not statistically significant (P = 0.499), whereas the differences between 3 and 12 months and between 6 and 12 months were significant after Bonferroni adjustment (both P < 0.001) (Table 1).

Table 1.

Preoperative and Postoperative Clinical Efficacy Scores of 25 Patients Included in the Study

Clinical Score	Number of Cases	Preoperative (x̄±s, points)	Postoperative 3 Months (x̄±s, points)	Postoperative 6 Months (x̄±s, points)	Postoperative 12 Months (x̄±s, points)	F Value	P Value
Lysholm	25	65.76 ± 2.73	93.24 ± 0.49	93.36 ± 0.47	94.36 ± 0.58	43.71	< 0.001
IKDC	25	50.07 ± 5.77	61.98 ± 4.50	91.20 ± 3.40	94.18 ± 3.50	648.95	< 0.001
VAS Score	25	5.24 ± 1.17	*2.28 ± 0.61	*2.16 ± 0.47	1.56 ± 0.65	△-4.36	< 0.001

*The VAS scores at postoperative 3 months and 6 months showed no significant statistical difference (P = 0.499), △ indicates the Z-value

Discussion

The principal finding of this study was that a small incomplete osteotomy at the femoral insertion of the LCL allowed adequate arthroscopic visualization and instrument access in selected patients with lateral meniscus tears and a tight lateral compartment. Osteotomy union was observed on 3-month CT, and no clinically apparent varus instability or serious complication was observed during 12 months of follow-up. Nevertheless, because this was a retrospective case series without a control group, the functional improvement and MRI healing rate cannot be attributed solely to the osteotomy itself.

Standard strategies for limited lateral compartment access include the figure-four position, portal adjustment, and gentle varus stress. In the medial compartment, MCL pie-crusting has been used because the MCL is broad and flat [7, 8]. These findings cannot be directly transferred to the lateral side because the LCL is thinner, cord-like, and biomechanically important for resisting varus stress [10–12]. For this reason, uncontrolled needle release of the LCL may be less forgiving than medial pie-crusting. The technique described here was used only after standard arthroscopic maneuvers failed to provide safe access.

Other lateral soft-tissue structures, including the iliotibial band, may contribute to lateral compartment tightness. We did not perform ITB pie-crusting in this cohort because the target of the procedure was the LCL femoral insertion, where temporary bony mobilization may increase the working space while preserving ligament continuity after refixation. A hanging figure-four position may also improve maneuverability in some cases. In the present series, all procedures were performed with the leg on the table to maintain controlled varus stress and stable arthroscopic orientation; this alternative should be considered and compared in future studies.

The LCL femoral-insertion osteotomies have previously been described for other indications around the knee. Conjeski et al. reported an osteotomy of the LCL femoral insertion during total knee arthroplasty for valgus knees, in which the LCL insertion was osteotomized en bloc and was not fixed at the end of the procedure [15]. Beel et al. described a complete osteotomy of the LCL femoral insertion for fixed valgus deformity during total knee arthroplasty, with fixation of the osteotomized bone fragment using high-strength sutures after the procedure [16]. Similar LCL femoral-insertion osteotomy has also been used to improve lateral exposure in tibial plateau fracture surgery [17]. However, the osteotomy technique described in the present study differs from these previously reported methods. In our technique, a small incomplete osteotomy is performed at the femoral insertion of the LCL, while the distal cortical hinge of the LCL femoral insertion is preserved. During the procedure, the osteotomized bone fragment remains in situ and is temporarily mobilized only to increase the lateral working space. At the end of the procedure, the bone fragment is reduced and fixed with high-strength sutures. Therefore, the novelty of the present work lies not in the anatomical maneuver of LCL femoral-insertion osteotomy itself, but in its specific indication: the use of a small incomplete osteotomy of the LCL femoral insertion as a temporary exposure-enhancing method for arthroscopic lateral meniscus repair in a tight lateral compartment.

The femoral insertion of the LCL is located slightly distal to the lateral femoral epicondyle and is approximately elliptical, with reported average anteroposterior and proximal-distal dimensions of about 10.3 mm and 11.7 mm, respectively [11, 18]. Because the osteotomized fragment is small, screw fixation may risk fragment fracture, staple fixation may be unstable in cancellous bone, and metal wire fixation may create irritation or require removal. In this series, transosseous high-strength suture fixation provided sufficient clinical stability, and CT demonstrated union without loss of reduction. However, no biomechanical testing or postoperative stress radiographic measurements were performed; thus, subtle laxity and fixation strength could not be quantified.

MRI at 12 months showed a meniscal healing rate of 76% according to the criteria of Schwach et al. [14]. The 6 patients who did not meet MRI healing criteria were asymptomatic and did not require reoperation during follow-up. This clinical correlation is encouraging, but MRI may both overestimate and underestimate true biological healing [19, 20], and second-look arthroscopy was not routinely performed. Future studies should include blinded MRI assessment, interobserver reliability, patient-reported outcome measures, and longer clinical surveillance.

This study has several limitations. First, it was retrospective, single-center, and included only 25 knees without a control group, preventing direct comparison with figure-four positioning alone, portal modification, hanging figure-four positioning, ITB release, or other techniques. Second, the definition of a tight lateral compartment was based on intraoperative functional assessment rather than an objective millimeter measurement. Third, the exact number of screened lateral meniscus repairs that did not require osteotomy could not be reconstructed because no prospective screening log was available. Fourth, postoperative stability was evaluated by physical examination rather than stress radiography or instrumented measurement. Fifth, the follow-up period of 12 months was relatively short for assessing late meniscal failure, cartilage degeneration, osteoarthritis progression, and late fixation-related complications. Prospective comparative studies with objective intraoperative gap measurement, biomechanical validation, stress radiographs, and longer follow-up are needed.

Conclusion

For selected patients with lateral meniscus tears and a tight lateral compartment that cannot be adequately opened using standard arthroscopic maneuvers, arthroscopic meniscal repair combined with incomplete osteotomy at the femoral insertion of the LCL may provide improved exposure and allow completion of meniscal repair with satisfactory short-term outcomes. However, the current evidence is limited by the retrospective design, small sample size, lack of a control group, absence of objective joint-space widening measurements, and short follow-up. The technique should therefore be considered a selective option rather than a routine procedure, and further prospective comparative studies are required.

Authors’ contributions

C.W. and X.C. contributed equally to this work. C.W. and H.Z. conceived and designed the study. C.W., Z.W., Z.C., and W.Y. collected the clinical data. X.C. prepared the figures and tables. C.W. drafted the manuscript. C.L. and H.Z. revised the manuscript critically for important intellectual content. All authors reviewed and approved the final manuscript.

Funding

This work was supported by the Research Project of Fujian Medical University Union Hospital (No. 2024XH032, 2024XH034). The funders had no role in study design, data collection, analysis, interpretation, manuscript preparation, or the decision to submit the manuscript for publication.

Data availability

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

This retrospective study was approved by the Institutional Review Board of Fujian Medical University Union Hospital (No. 2024KY097). All procedures involving human participants were conducted in accordance with the ethical standards of the institutional and national research committee and with the Declaration of Helsinki and its later amendments. Written informed consent was obtained from all patients prior to surgery.

Consent for publication

Not applicable. The manuscript does not contain identifiable individual patient data.

Competing interests

The authors declare no competing interests.