Modified Gerdy tubercle osteotomy in the treatment of posterolateral tibial plateau depression fractures: Technical report and preliminary results

Abstract

BACKGROUND

Tibial plateau fractures are clinically common. Among various classification systems, the six-type Schatzker classification is most widely used. This report focuses on Schatzker type 3 (simple lateral plateau depression fracture) and type 5 with lateral plateau depression. Depression fractures can occur anywhere on the lateral plateau, most commonly in the central-posterior region. Uncorrected intraoperative depression may cause knee bony instability and impair joint function.

AIM

To modify Gerdy tubercle osteotomy was used to treat these fractures, yielding favorable postoperative and functional outcomes of the knee.

METHODS

This study included a cohort of 18 patients, including 11 males and 7 females, 10 left knees and eight right knees. The age ranged from 30 years to 56 years, with an average of 35.6 years. All 18 patients were treated with modified Gerdy tubercle osteotomy and followed up until the end of the observation. Radiological outcomes including fracture reduction loss and fracture healing were assessed via postoperative follow-up knee X-ray and computed tomography examination. Knee functional recovery was evaluated using the Hospital for Special Surgery score and Lysholm knee score.

RESULTS

By the end of follow-up, no fracture loss was observed in any of the patients, and the fractures were completely healed. According to the Lysholm knee function score, 15 cases were excellent, two were good, and one was fair, with an excellent-good rate of 94%. According to the Hospital for Special Surgery score, 14 cases were excellent, three were good, and one was fair, with an excellent-good rate of 94%.

CONCLUSION

The modified Gerdy osteotomy method for treatment of posterolateral tibial plateau depression fractures involves a simple surgical operation, satisfactory fracture reduction, and excellent recovery.

Key Words: Gerdy tubercle osteotomy; Tibial plateau fracture; Surgical techniques; Clinical prognosis

Core Tip: This study focused on Schatzker type 3 (i.e., simple lateral plateau depression fracture) and Schatzker type 5 with lateral plateau depression fractures. Schatzker type 3 fractures are mostly caused by direct impact of the femoral condyle on the lateral plateau. The depressed fracture can occur at any position on the lateral plateau, and the central-posterior position is more common. If the depression is not corrected during surgery, it may cause knee joint bony instability and have a significant impact on joint function. We used the modified Gerdy tubercle osteotomy to treat this type of fracture and achieved good results.

INTRODUCTION

Tibial plateau fractures are common in clinical practice. Due to the complexity of their anatomical structure, combined with the diversity of injury mechanisms and imaging manifestations, various classification methods have been proposed, including the Arbeitsgemeinschaft für Osteosynthesefragen classification, and Zhu et al’s three-column classification[1]. The most commonly used is the Schatzker classification, which has six types in total. This study focused on Schatzker type 3 (i.e., simple lateral plateau depression fracture) and Schatzker type 5 with lateral plateau depression fractures. Schatzker type 3 fractures are mostly caused by the direct impact of the femoral condyle on the lateral plateau. The depressed fracture can occur at any position on the lateral plateau, and the central-posterior position is more common (Figure 1). If the depression is not corrected during surgery, it may cause knee joint bony instability and have a significant impact on joint function. There are many surgical approaches for this type of fracture, such as the posterior-medial approach to expose the posterolateral side[2], direct posterolateral approach, Frosch approach[3], fibular neck osteotomy approach[4], and lateral cortex fenestration approach. However, each approach has its advantages and disadvantages. We used the modified Gerdy tubercle osteotomy approach to treat this type of fracture and achieved good results, and report a typical case below.

Figure 1 Schatzker type 3 fractures.

MATERIALS AND METHODS

Patient characteristics

A retrospective review was performed on 18 consecutive patients with posterolateral tibial plateau depression fractures treated with modified Gerdy tubercle osteotomy at Shulan (Hangzhou) Hospital between March 2018 and June 2024. The study protocol was approved by the Ethics Committee of Shulan (Hangzhou) Hospital, and written informed consent was obtained from all individual participants prior to enrollment.

Exclusion criteria were as follows: (1) Patients with severe comorbidities precluding surgical intervention; and (2) Patients with active local infection or severely contaminated open fractures that were unsuitable for plate internal fixation.

Typical case: A 32-year-old woman experienced pain in her right lower limb due to a car accident. The patient’s right knee joint had intact skin, soft tissue swelling, obvious tenderness, limited mobility, and a palpable bone friction sensation. Due to pain, no other tests such as lateral stress testing were conducted. Preoperative computed tomography (CT) scan of the tibial plateau (Figure 2A and B) indicated a posterolateral tibial plateau depression fracture.

Figure 2 Postoperative follow-up imaging. A: Preoperative computed tomography (CT) sagittal scan of tibial plateau showing a posterior tibial plateau depression fracture; B: Preoperative coronal CT scan of the tibial plateau showing a depressed fracture on the lateral side of the tibial plateau; C: Postoperative follow-up X-ray positive position film. D: Postoperative follow-up X-ray lateral view film; E: Postoperative follow-up CT coronal scan; F: Postoperative follow-up CT sagittal images (C-F: Postoperative follow-up X-ray and CT scan showing healing of the fractures and osteotomy blocks). There was no bone collapse, nonunion, or infection.

Final diagnosis

Combined with the patient’s medical history, the final diagnosis was a fracture of the right tibial plateau (Schatzker type 3).

Surgical procedures

After the anesthesia took effect, the patient was placed in the supine position, and routine disinfection and draping were carried out. A 3-cm incision was made on the ipsilateral iliac crest, a piece of autologous bone was removed, cut it into granules for bone grafting, and the incision was sutured and bandaged. An anterior-lateral curved incision of the knee joint was made through the Gerdy tubercle, approximately 10 cm long. The skin and subcutaneous tissue were incised, hemostasis was achieved, and the iliotibial tract was exposed while protecting its integrity (Figure 3A). The tibial collateral ligament of the lateral meniscus was partially incised and sutures were used to traction and fix the meniscus proximally. If there was a tear in the meniscus, it could be sutured and repaired first. The knee joint was in varus alignment, and obvious joint surface depression could be seen from the joint space. In the attachment area of the iliotibial tract on the Gerdy tubercle, a thin osteotome was used to make an inverted L-shaped osteotomy in front of and below the Gerdy tubercle (Figure 3B), leaving the posterior soft-tissue hinge to facilitate later healing. At the same time, the neatness of the joint surface margin and the integrity of the iliotibial tract were protected. The osteotomy block was lifted together with the iliotibial tract upward and backward, and the depressed fracture could be clearly seen (Figure 3C). The fracture block was lifted, the joint surface was rebuilt under direct vision, and temporarily fixed with Kirschner wires under the joint surface. Sufficient bone grafting (usually mainly autologous iliac bone) was carried out under the bone block, the Gerdy osteotomy block was filled back to restore the integrity of the joint surface. The block was fixed with Kirschner wires, and an L-shaped locking anatomical plate was placed on the anterior-lateral side of the proximal tibia (Figure 3D). This was fixed with multiple screws for support. If the osteotomy block was large, cannulated lag screws could be added for fixation. Under fluoroscopy, the fracture reduction was satisfactory and the internal fixation was appropriate (Figure 3E and F). After irrigating the joint, the lateral meniscus was sutured to the plate, ensuring it was not too tight. The knee joint was checked for movement, complete hemostasis after irrigation was achieved, suture was made layer by layer, and the operation was completed. Usually, no drainage tube was placed.

Figure 3 Surgical procedure and intraoperative imaging. A: Exposure of the iliotibial tract; B: Use of a thin osteotome to make an inverted L-shaped osteotomy in front of and below the Gerdy tubercle (arrow); C: Lifting the osteotomy block together with the iliotibial tract upward and backward, clearly showing the depressed fracture (arrow); D: Fixation with Kirschner wires, and placement of an L-shaped locking anatomical plate on the anterior-lateral side of the proximal tibia; E and F: Under fluoroscopy, the fracture reduction is satisfactory and the internal fixation is appropriate.

Postoperative management

Cefuroxime was administered routinely within 24-48 hours after surgery to prevent infection, along with regular anti-inflammatory and analgesic treatments. According to the principle of early movement, late weight-bearing, on postoperative day 1, active and passive knee joint exercises were carried out in bed, focusing on muscle strength and joint range of motion exercises. There was no need to use a continuous passive motion machine device for assistance, and weight-bearing on the ground was strictly prohibited. X-rays were repeated monthly for 3 months after surgery. According to the fracture healing situation, gradual partial weight-bearing on the ground usually starts at 8-12 weeks after surgery, and sports and physical activities can be gradually resumed 6 months after surgery.

RESULTS

Follow-up knee X-rays and CT scans of patients are used to evaluate the fracture reduction loss and fracture healing. The Hospital for Special Surgery (HSS) score and the Lysholm knee function score were used to evaluate the knee joint function. The HSS score[5] was: Excellent > 85 points; good 70-84 points; fair 60-69 points; and poor < 59 points. The Lysholm knee function score[6] was: Excellent ≥ 95 points; good 85-94 points; fair 65-84 points; and poor < 65 points. Clinical outcomes of the patients were evaluated during follow-up at 1 month, 3 months, 6 months, and 12 months after surgery. The preliminary evaluation was conducted by a research doctor during hospitalization, and follow-up by outpatient visits after discharge.

The clinical efficacy of the patients was evaluated during follow-up at 1 month, 3 months, 6 months, and 12 months after surgery. The fractures and osteotomy blocks healed, with an average healing time of 3.0 months. There was no bone collapse, nonunion, or infection. Some patients had their internal fixation removed. According to the HSS score, 14 cases were excellent, three were good, and one was fair, with an excellent -good rate of 94%. According to the Lysholm score, 15 cases were excellent, two were good, and one was fair, with an excellent-good rate of 94%.

The postoperative follow-up in the above representative case showed good clinical efficacy, and the internal fixation has been removed (Figure 2).

DISCUSSION

Understanding the injury mechanism of this type of fracture is helpful for preoperative planning and guiding intraoperative reduction and fixation. This type of fracture is generally caused by high-energy impact. At that time, when the knee joint is in a straight or flexed state, the axial injury combined with the varus-valgus stress can make the femoral condyle exert pressure on the tibial plateau, resulting in joint surface depression. Combined with the anatomical characteristics of the knee joint, the lateral plateau is higher, and the knee joint has a normal valgus angle of 10°. In daily life, the knee joint is more often subjected to impact from the outside to the inside than from the inside to the outside. Therefore, depression of the lateral plateau is more common. If the depression cannot be restored during surgery or secondary depression occurs after surgery, it may lead to knee joint bony instability, traumatic arthritis, and joint pain, affecting normal walking, especially activities such as going up and down stairs. In severe cases, revision surgery is required.

Compared with the traditional Gerdy tubercle osteotomy, the modified approach retains the complete iliotibial tract and the posterior soft-tissue hinge of the Gerdy tubercle, which is beneficial to the stability of the lateral side of the knee joint and healing of the osteotomy block. When filling back the bone block, anatomical reduction of the joint surface can be achieved. Compared with the posterior-medial approach to expose the posterolateral side, the exposure range of the posterior-medial approach is limited. Due to the presence of the posterior cruciate ligament, true direct-vision reduction and fixation cannot be achieved, and only a small plate can be placed in the space for auxiliary fixation. Main-force plates on the inner and outer sides are still needed for support and fixation. Compared with the posterolateral Frosch approach and the fibular neck osteotomy approach, although the exposure is better, the posterolateral anatomical structure is complex, with more damaged blood vessels and soft tissues, which may affect the posterolateral stability of the joint. Also, only a small plate can be placed, and the supporting force is insufficient. Compared with the fenestration approach below the lateral plateau, the fenestration approach is simple and does not increase damage to the joint surface. However, it can only check the fracture reduction through the narrow joint space, and the reduction is also achieved by indirectly lifting the bone block through the lower window. In the actual operation, it is difficult to achieve anatomical reduction of the joint surface. Some good results have been achieved by combining arthroscopic reduction[7], but this requires greater technical skills from the operating surgeon. In recent years, the balloon-assisted reduction technique[8] has also achieved some results, but it still belongs to indirect reduction. Coupled with cost factors, it has not been widely carried out to date.

During the operation, the iliotibial tract and its attachment point on the Gerdy tubercle are carefully dissected, retaining the posterior soft-tissue hinge of the Gerdy tubercle. A wide, thin osteotome is used to ensure a smooth and even joint surface for anatomical alignment during reduction. The angle of the osteotome when cutting should refer to the preoperative CT horizontal plane image, and it should reach the depressed area directly to maximize the exposure. A bone elevator is used to completely lift the bone block to reduce the joint surface, and maintain the integrity of the depressed bone block. One or two Kirschner wires are inserted under the joint surface for temporary fixation, fully bone graft in the depressed area below, then the osteotomy block is reduced, fixed with Kirschner wires, and replaced with a plate for fixation after satisfactory fluoroscopy. Anatomical reduction of the joint surface and raft screws support fixation of the proximal plate and sufficient bone grafting below is the key to avoiding secondary collapse of the plateau[9].

For fractures involving the posterolateral tibial plateau with posterolateral splitting, additional plate support fixation is required at the back. This approach alone cannot solve the problem, and combined applications such as the anterior-lateral and posterior-medial approach are often needed.

CONCLUSION

The modified Gerdy osteotomy approach is simple to operate. After osteotomy, it can directly reach the fracture area, and the linear distance from the depressed bone block is short. Although it also increases the damage of joint surface osteotomy, it significantly expands the surgical field. The reduction of the depressed fracture and the osteotomy block can be operated under direct vision, and anatomical reduction and fixation can be achieved. This is crucial for maintaining the stability of the knee joint, restoring joint function, reducing long-term wear of articular cartilage, and avoiding secondary collapse of the joint surface. Based on our experience and the prognosis of patients, we believe that this method is worthy of clinical promotion.