© The Authors, published by EDP Sciences, 2025

Introduction

Traditionally, the medial approaches are used for total knee arthroplasty (TKA) [1, 2]. In valgus TKA, the medial approach offers limited access to the pathologic anatomy and presents technical challenges, including restricted posterolateral exposure, increased tibial external rotation, compromised lateral vascularity, and risk of excessive lateral release [3, 4] (Table 1). In contrast, the lateral approach allows direct access to valgus pathology, enabling efficient lateral release through exposure, improved posterolateral access via tibial internal rotation, and sequential gap balancing [1]. It also preserves medial vascularity, ensures adequate soft tissue management, optimizes patellar tracking, and supports rehabilitation by maintaining medial quadriceps integrity [2].

This surgical technique article outlines a step-by-step, structured approach to TKA using the lateral approach in patients with valgus deformity. Key technical steps, indications, and tips for optimal exposure and closure are outlined to assist in managing these cases effectively.

Surgical technique

Table 2 and Video 1 provide a step-by-step guide for the lateral approach in TKA.

Positioning

The patient is placed in the supine position with a lateral support at the thigh and a foot bolster to stabilize the limb. The surgical leg is prepared and draped in a sterile manner, with care taken to allow for a full range of motion during the procedure. Standard prophylactic antibiotics are administered before incision.

Skin incision and initial exposure

A lateral parapatellar incision is performed, beginning approximately 2–3 cm proximal to the patella and extending distally toward the tibial tubercle. A two-layer capsulotomy is executed: the initial superficial cut is made on the side away from the patella, followed by dissection inward, and finalized with a deep incision adjacent to the patella. This sequence preserves capsular integrity and facilitates secure closure. A 1 cm overlap of the lateral joint capsule is intentionally left to enable anatomic reapproximation during closure (Figure 1).

Figure 1 Exposure with the lateral approach. A lateral parapatellar approach with a two-layer capsulotomy, leaving a 1 cm overlap, is used.

Soft tissue handling and Hoffa fat pad management

Preservation of the Hoffa fat pad is prioritized to assist in closure of the distal portion of the incision, especially after significant valgus correction. The fat pad is carefully dissected from the undersurface of the patellar tendon, minimizing unnecessary excision to maintain structural support and facilitate joint sealing (Figure 2).

Figure 2 The lateral parapatellar approach involves a two-layer capsulotomy, leaving a 1 cm tissue overlap on both sides of the incision (green and blue areas) for secure closure, while preserving as much fat pad as possible behind the patellar tendon (yellow area) to facilitate capsular closure.

Patellar management and tibial access

The patella is everted with the knee in extension, followed by flexion to 90 degrees, to facilitate deep exposure (Figure 3). This maneuver allows direct visualization and access to the lateral femoral condyle and posterolateral tibia.

Figure 3 Exposure of the knee joint after reverting the patella with the knee in extension, then flexing the knee to 90 degrees.

Bone preparation

During the femoral preparation, the gap between the distal femoral cutting guide and the lateral femoral condyle, often altered due to dysplasia or wear, is measured to guide subsequent posterior condylar balancing (Figure 4). After completing the distal femoral cut, the femoral guide is aligned with the Whiteside line, and an osteotome is used to recreate the previously measured gap posteriorly. A contralateral tibial cutting guide is employed to improve access and protect the patellar tendon during tibial preparation (Figure 5). Bone cuts are performed using an intramedullary guide for the femur and intra- or extramedullary alignment for the tibia. The tibial guide is shifted proximally by 2 mm to compensate for the lower medial plateau reference. Flexion of the knee is maximized, and the tibia is subluxed anteriorly and externally rotated to expose the posteromedial plateau. Osteophytes are thoroughly removed, particularly posteromedially, and both menisci are excised.

Figure 4 Key steps during the main procedure: Measurement of the gap between the distal femoral cutting guide and the lateral femoral condyle.

Figure 5 A contralateral cutting guide to perform the tibial cut is utilized for better access of the cutting saw without the risk of injuring the patellar tendon.

Sequential lateral releases

The tight lateral structures, including the lateral capsule, iliotibial band, and vastus lateralis tendon, are sequentially released based on intraoperative assessment of gap balancing. In rare cases with fixed deformity, additional release of the lateral collateral ligament, popliteus tendon, or lateral gastrocnemius may be required. These structures are accessed efficiently through the lateral approach, and releases are titrated to restore coronal alignment and ensure stability.

Medial exposure considerations

Despite limited access to the posteromedial side, this approach provides sufficient visualization for bone preparation without requiring tibial tubercle osteotomy. In most cases, adequate medial exposure is achieved without additional extensile maneuvers (Figure 6).

Figure 6 Exposure of the posteromedial tibial plateau.

Implantation and closure

Once the bone cuts and trial confirm satisfactory balance and alignment, the definitive prosthetic components are implanted. Closure begins distally in the angular position and proceeds proximally. The overlapping layers of the capsule are sutured meticulously, reinforced by the retained distal fat pad, which is folded into the closure for additional support. Any redundant portions of the fat pad are trimmed to avoid bulk beneath the skin (Figure 7).

Figure 7 Closure of the lateral approach: Any remaining fat pad distally is used to reinforce joint closure.

Discussion

This surgical technique aims to provide a reproducible and effective method for performing TKA in patients with valgus deformity using the lateral approach. The lateral approach offers several advantages in managing valgus pathology, including direct access to contracted lateral structures, preservation of medial soft tissues, and improved control of patellar tracking. To optimize the outcomes of this technique, several critical steps have been emphasized. First, a 1 cm overlap of the lateral joint capsule is deliberately maintained to facilitate reliable capsular closure following deformity correction. This is achieved by incising the capsule in a stepwise manner, starting superficially on the side opposite the patella, progressing through careful dissection, and finishing with a deep incision adjacent to the patella, to avoid misalignment during closure. Second, preservation of the Hoffa fat pad is recommended, particularly distally, as it can be instrumental in achieving a tension-free closure after valgus correction. Third, the use of a contralateral tibial cutting guide improves access to the tibial plateau and protects the patellar tendon during bone preparation.

The primary indication for the lateral approach in TKA is the presence of a valgus deformity. Fixed valgus deformity often presents with unique anatomical challenges, such as lateral femoral condyle hypoplasia, femorotibial malrotation, resorption of the lateral femoral condyle and tibial plateau, and an enlarged medial condyle [5–7]. Tight lateral structures and a frequently deformed, subluxed patella over the lateral condyle are common features [8]. Soft tissue deficiencies in this region can pose challenges for achieving adequate prosthetic coverage and joint seal. Correcting fixed contractures in valgus TKA typically involves a sequence of potential releases, including the lateral capsule, iliotibial band (ITB), vastus lateralis tendon, and, in rare cases, the lateral collateral ligament (LCL), popliteus, lateral gastrocnemius, and fibular head (where the LCL is preserved and lengthened) [8, 9]. These releases are most effectively achieved through direct lateral access.

This approach has few contraindications. It may be unsuitable if a previous scar is located within 6–8 cm of the incision site, as the skin bridge between them could be at risk of compromised viability [2, 5]. Additionally, due to the limited access to the posteromedial side of the knee in comparison to medial approaches, this technique is generally not recommended for cases with varus deformity, as releasing medial contractures can be challenging from the lateral side [2, 10]. Furthermore, in valgus cases where the axial deformity is greater than 20°, and the medial stabilizers are not functional, if a medial capsular plication is planned, then the lateral approach should not be used.

The choice of surgical approach for TKA in valgus knee remains a topic of debate. Key technical elements, including surgical exposure, bone cuts, and ligament balancing, are essential to achieving proper alignment and stability. Selecting the appropriate surgical approach is critical and forms the foundation of effective preoperative planning. Recent meta-analyses have shown that patients undergoing TKA with a medial approach demonstrated, on average, comparable postoperative Knee Society Scores (KSS) and flexion range of motion (ROM) to those treated with a lateral approach [1, 7]. Both approaches showed similar surgical times, postoperative hip-knee-ankle (HKA) angles, KSS function scores, and complication rates [1, 7]. Furthermore, another meta-analysis by Xu et al. revealed higher KSS and KSS function scores in patients treated with the lateral approach, while both the lateral and medial approaches showed comparable results in surgical time, range of motion (ROM), correction of valgus knee deformity, and overall complication rates [6]. The lateral approach in valgus knees can also be utilized in image-based robotic TKA, without problems during pins’ insertion and the workflow of the surgery [11–13].

With adequate experience, the risk of complications with this approach is minimal. Component alignment has been consistently accurate in various studies, and patellar tracking is optimized, reducing the likelihood of patellar instability. However, peroneal palsy remains a risk, especially in severe fixed valgus deformities. Excessive retraction or unintentional dissection may heighten the risk to the peroneal nerve. Hematoma, a potential source of compressive neuropathy, can be minimized with proper hemostasis [14]. Postoperative complications may also include difficulties in joint capsule closure, postoperative effusion, and poor incision healing [7, 14].

Conclusion

The lateral approach for TKA in valgus deformity offers safe and reproducible access to the pathologic anatomy, facilitating effective alignment and patellar tracking without the need for tibial tubercle osteotomy. Further studies are warranted to confirm its long-term outcomes across broader patient populations.

Funding

This research received no external funding.

Conflicts of interest

Authors 1, 2, 3 have nothing to declare. Author 4: Consultant for Smith and Nephew and Stryker. Author 5: Consultant for Smith and Nephew. Author 6: Royalties from Smith Nephew, Stryker, and Serf. Consultant for Stryker, Heraeus; Institutional research support from Amplitude and Groupe Lepine; Editorial Board for Journal of Bone and Joint Surgery (Am).

Data availability statement

Data is available upon reasonable request to the corresponding author.

Author contribution statement

Author 1: Conceptualization, Methodology, Data curation, Writing an original draft.

Author 2: Conceptualization, Methodology, Data curation, Writing an original draft.

Author 3: Data curation, Methodology, Writing, Reviewing, and Editing.

Author 4: Data curation, Methodology, Writing

Author 5: Conceptualization, Methodology, Writing, Reviewing.

Author 6: Conceptualization, Supervision, Validation, Writing, Reviewing, and Editing.

Ethics approval

Ethical approval was not required.

Informed consent

Written informed consent was obtained from the patient depicted in the technique presentation.

Supplementary material

Video 1: The step-by-step technique for the lateral approach for total knee arthroplasty is presented. Access here

References

All Tables

All Figures

	Figure 1 Exposure with the lateral approach. A lateral parapatellar approach with a two-layer capsulotomy, leaving a 1 cm overlap, is used.
In the text

	Figure 2 The lateral parapatellar approach involves a two-layer capsulotomy, leaving a 1 cm tissue overlap on both sides of the incision (green and blue areas) for secure closure, while preserving as much fat pad as possible behind the patellar tendon (yellow area) to facilitate capsular closure.
In the text

	Figure 3 Exposure of the knee joint after reverting the patella with the knee in extension, then flexing the knee to 90 degrees.
In the text

	Figure 4 Key steps during the main procedure: Measurement of the gap between the distal femoral cutting guide and the lateral femoral condyle.
In the text

	Figure 5 A contralateral cutting guide to perform the tibial cut is utilized for better access of the cutting saw without the risk of injuring the patellar tendon.
In the text

	Figure 6 Exposure of the posteromedial tibial plateau.
In the text

	Figure 7 Closure of the lateral approach: Any remaining fat pad distally is used to reinforce joint closure.
In the text