Chondroblastoma is a rare, nonmalignant but invasive tumor. The effects of various surgical methods are also controversial. This the object of this article is to share the treatment experience of femoral head chondroblastoma without surgical dislocation in our medical center from 2017 to 2023.
Currently, the most prevalent locations of chondroblastoma in children are the distal femur, proximal tibia, and proximal humerus, although there is debate regarding which of these sites has the highest incidence rate [4, 5, 7, 11]. Nonetheless, chondroblastoma affecting the femoral head is uncommon. The majority of pediatric patients primarily complain of pain, sometimes accompanied by lameness. Due to its distinct anatomical position, the surgical approach is more intricate than that for chondroblastoma in more common sites.
Strong has proposed three surgical approaches to removing the lesions in the femoral head. The first route involved accessing the lesion through a bone tunnel from the outside of the proximal femur along the long axis of the femoral neck to the femoral head (known as curettage via the femoral neck, or CVFN). The second route involved a direct approach through the head-neck junction below the growth plate or the femoral neck. The third route was traditional trapdoor procedure [12]. Two out of the five children who underwent the CVFN approach experienced local recurrences. When this surgical approach was employed, the lesion located in the femoral head could not be directly visualized, and the precise delineation between the lesion and healthy tissue remained elusive. The extensive pathway through the femoral neck to access the lesion posed challenges, as the curette or other surgical instruments could not easily reach all areas of the tumor, thereby hindering its complete removal. Additionally, the CBL tissue was soft and left in the path which may increase the risk of recurrence [4, 12]. Furthermore, the study has shown that this surgical approach could potentially harm the epiphyseal plate of the femoral head in children. In fact, an 11-year-old patient who underwent CVFN surgery experienced a minor shortening (< 1cm) of the affected lower limb a year after the operation [12]. Hence, CVFN was not considered the most effective method. Although Strong did not report any occurrences of femoral head necrosis, the second surgical approach undoubtedly damaged the blood vessels supplying the femoral head, thus increasing the risk of necrosis. Furthermore, this approach also caused harm to the growth plate. Although this technique undeniably enhanced the surgeon's field of vision, achieving comprehensive tumor curettage through this method remained challenging during the actual surgical procedure. The traditional trapdoor procedure required extreme caution during the operation to dislocate the hip joint. However, even with such precautions taken, there was still a risk of damaging the articular surface of the femoral head, which could increase the chance of femoral head necrosis [13, 14].
In recent years, Liu et al. have put forward the modified trapdoor procedure. The difference between this surgery and the traditional trapdoor procedure was that ligamentum teres was used to close the window on the cartilage surface. Of the 13 children, one child developed necrosis of the femoral head four months postoperatively, another exhibited heterotopic ossification, while the remaining children had a favorable prognosis during the follow-up period [15]. We believe that the modified trapdoor procedure exhibits a favorable therapeutic outcome; however, it is not suitable for the lesions on the edge of the femoral head surface. Additionally, surgical excision of the ligamentum teres of the femoral head can compromised the blood supply to the femoral head, thereby elevating the risk of femoral head necrosis. Ganz et al. have previously demonstrated that the blood supply to the femoral head primarily originates from the deep branch of the medial femoral circumflex artery (MFCA) [13]. However, numerous authors have reported the existence of ligamental arteries and their significant contribution to the blood supply of the femoral head [16, 17]. The role of the ligamentum teres remains controversial. We tend to preserve the ligamentum teres, which we believe will result in a more favorable prognosis for children. The smooth texture of the ligamentum teres does not match the articular cartilage found on the femoral head surface. Furthermore, the potential for developing secondary osteoarthritis among children who were treated with the modified trapdoor procedure remained uncertain when compared to other surgical options, especially in long-term follow-up studies. Articular cartilage primarily receives its nutritional supply from synovial fluid, and numerous successful instances of osteochondral transplantation have unambiguously established the viability of articular cartilage replantation [18–20]. Therefore, in our treatment, we recommend autologous articular cartilage replantation to ensure the smoothness of the femoral head surface.
In the surgery of curettage without hip dislocation for femoral head CBL, only a few articles have described the surgical process in detail. In 2022, Hirohisa Katagiri reported on two patients who underwent focal curettage of the femoral head without hip dislocation. These two patients did not experience any complications during the 6 and 12-year follow-ups, respectively. Unlike in our surgical approach, Katagiri chose a non-weight-bearing area for fenestration [21]. Currently, there are no clear reports regarding the impact of fenestration in weight-bearing versus non-weight-bearing areas on prognosis.
In the curettage of CBL in the femoral head, it has always been a concern to avoid the injuring the epiphyseal plate of the femoral head. The epiphyseal plate of femoral head promotes the elongation of femoral neck [22]. It has been proved that simple curettage leads to higher possibility of local recurrence. Tomic et al. observed that the recurrence rate of surgical treatment with simple curettage was high (as high as 30%), which they deemed unacceptable, especially for invasive lesions [23]. Extended curettage can significantly reduce the risk of local recurrence in chondroblastoma of the femoral head. However, it may exacerbate the damage to the epiphyseal plate [11]. Suneja et al. have stated that the damage to the epiphyseal plate can be repaired through appropriate post-operative nursing care. In their study, all patients underwent aggressive intralesional curettage as the sole treatment, which proved curative in most cases. However, the authors did not provide comprehensive data on the status of the epiphyseal plate for all patients [3]. Liu Qing et al. postulated that the epiphyseal plate near the knee joint possesses resilience and has the potential to regenerate following extensive curettage. This assertion was based on two primary reasons: Firstly, only a minor portion of the epiphyseal plate is associated with the tumor. Secondly, the blood supply to the epiphyseal plate originates from the soft tissue connected to the epiphysis, which remains largely unaffected during the surgical procedure [24]. Another study found that out of 20 children treated with extended curettage, only 2 experienced relapse, with no cases of leg length discrepancy (LLD) reported. It's worth noting that most of the patients had epiphyseal plates that were either closing or already closed, with only one child having an open epiphyseal plate[5]. It is widely believed that the risk of LLD is lower when the epiphyseal plate is in a closed state compared to an open state. Mashhour and Abdel Rahman recommended extended curettage during the initial surgery to reduce the chances of recurrence [25]. However, whether extended curettage can effectively treat CBL in the femoral head needs further investigation. In our study, we prioritized protecting the epiphyseal plate as much as possible, while ensuring complete removal of the lesion.
During our surgical procedure, we applied anhydrous alcohol to deactivate any remaining tumor cells within the cavity. Among the locally available adjuvants, such as burring, liquid nitrogen, phenol, and cement, high-speed burring is predominantly used. It is widely acknowledged as the most effective adjuvant for preventing local tumor recurrence [2, 7, 26]. However, Cong Huang et al. expressed concern that the epiphyseal plate could potentially be harmed by the heat generated by the burr [11]. Additionally, cement was also regarded as detrimental to the epiphyseal plate due to the heat it emitted during the solidification process [7]. Furthermore, studies have indicated that adjuvants like phenol or liquid nitrogen may induce necrosis [15]. Currently, there is a scarcity of published data examining the use of anhydrous alcohol as an adjuvant in the treatment of CBL. Anhydrous alcohol has the potential to induce protein denaturation in tumor cells, cytoplasmic degeneration, and embolism of the small vessels supplying the tumors. Furthermore, it has been established that anhydrous alcohol exerts minimal adverse effects on surrounding tissues [27]. Karem advocated for the use of phenol and anhydrous alcohol as adjuvants in curettage [5]. However, our findings revealed that anhydrous alcohol alone can achieve satisfactory surgical outcomes.
Secondary osteoarthritis is a prevalent complication associated with CBL of the femoral head [17]. Studies have indicated that CBL located specifically in the hip joint, particularly the femoral head, is often linked to extended curettage of lesions and the utilization of adjuvants like phenol and liquid nitrogen, factors that may contribute to the development of secondary osteoarthritis. Farfalli previously noted that while extended curettage can decrease the likelihood of recurrence in pediatric patients, it also elevates the risk of secondary osteoarthritis [14]. The unique and delicate circulatory system of the hip joint may contribute to degenerative changes observed in this condition [28]. In the management of comparable tumors, such as giant cell tumors, phenolic compounds demonstrated a reduced risk of osteoarthritis compared to liquid nitrogen [29, 30]. Farfalli et al. demonstrated that the incidence of secondary osteoarthritis increased after first 5 years of follow-up [14], which was a limitation that we cannot explore due to insufficient follow-up time.
When addressing CBL of the femoral head, the chosen surgical approach varied based on the lesion's location and extent. If the lesion was wholly contained within the femoral head and had minimal or no impact on the epiphyseal plate, we opted to create a window through the articular cartilage of the femoral head. However, if the epiphyseal plate lesion was significant and the CBL extended considerably into the femoral neck, we contemplated opening a window through the femoral neck to extract the tumor. This method helped to reduce harm to the articular cartilage, thereby maintaining joint integrity and functionality.
Our research encountered several limitations. Firstly, there were few cases of femoral head involvement, which limited our ability to obtain more precise risk factors through our research. Secondly, our follow-up period was insufficient to adequately assess long-term complications.