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Back to Journal »Orthopedic Research and Review» Volume 13
Single-compartment knee replacement for severe osteoarthritis and false joints in patients with neurofibromatosis
Author Balaji A, Toga A, Kano J, Fujimaru A, Matsumoto T, Katoh S
Published on May 14, 2021, Volume 2021: 13 pages, 63-71
DOI https://doi.org/10.2147/ORR.S304651
Single anonymous peer review
Editor who approved for publication: Professor Clark Hung
Video abstract of "Single-compartment knee replacement for severe osteoarthritis" [ID 304651].
Ayush Balaji, Akira Toga, Jun Kano, Atsuki Fujimaru, Taisuke Matsumoto, Shojiro Katoh Orthopedics, Edogawa Hospital, Tokyo, Japan Newsletter: Akira Toga Orthopedics, Edogawa Hospital 2-24-18 Edogawa-ku Higashikoiwa, Tokyo, 160-8582, Japan Tel 81-3-3673-1221 Fax 81-3-3673-1229 Email [email protected] Abstract: We describe a 76-year-old Asian female patient with severe pain and valgus deformity in her right knee. Her past medical history included neurofibromatosis, which resulted in severe anterior leaning of the right knee, shortened limbs, and congenital prosthetic joints. She was diagnosed with severe anterior lateral osteoarthritis and a burning sensation in the right knee, and underwent surgical treatment with a lateral single-compartment knee arthroplasty (UKA). Remove bone and cartilage fragments from the joint space and insert a UKA implant (Zimmer®) measuring 29 mm × 50 mm. Perioperative imaging showed that the surgery resulted in the correction of the valgus deformity. The pain was relieved immediately after the operation, and the patient was able to walk 10 meters under support. One week after the operation, the patient had an oblique fracture of the tibia, extending from the medial edge of the implant to the medial bevel of the proximal tibia. This complication may be due to excessive implant size or overcutting of the sagittal plane. The fracture was treated surgically with a rotating anterolateral locking plate (ALPS®) inserted into the distal tibia. Two months after the second operation, the patient was able to walk under full load. It is critical to realize that there is no standard protocol that can be used to guide the treatment of neurofibromatosis-induced osteoarthritis. The specific preoperative condition of an individual patient plays an important role in determining the appropriate treatment plan. In this case, the availability of customized UKA implants may improve prospects. We know that these devices are expensive and may not be available in all hospitals. However, we firmly believe that the "gold standard" in these cases is a specific treatment for the patient, using the resources available at the time to solve the most concerned issues. Keywords: skeletal deformities, limb shortening, stress fractures, knee implants
In this report, we reviewed a 76-year-old Asian woman who had a history of neurofibromatosis (NF), congenital pseudoarthropathy, and osteogenesis disorders, as well as osteoarthritis (OA) of the right knee. NF is a genetic disease that causes tumors to grow throughout the nervous system. 11 Type 1 NF is caused by mutations in the gene encoding neurofibrin on chromosome 17, which is a GTPase activating protein that regulates cell growth. Type 1 NF is a rare disease, reported to occur in 1 in every 4000 live births worldwide. 2 Patients diagnosed with NF often observe skeletal deformities. A review of the medical literature shows that the prevalence of NF and skeletal deformities (including congenital pseudoarthropathy) is higher than previously recognized. 3 Patients with NF have also been diagnosed with arthritis, although to date all reports except one have focused on pathology. 4 There are no reports on the detailed results of knee arthroplasty and open reduction and internal fixation in patients with NF. Therefore, with the exception of amputation, no comprehensive treatment plan has been developed to guide the management of knee NF orthopedic performance.
A 76-year-old woman presented to our clinic with symptomatic OA in her right knee. At the time of admission, she was 139.8 cm tall and weighed 46.5 kg. Her past medical history includes NF, congenital pseudoarthrosis, and syndesmosis deformity leading to shortening of the right lower extremity. At the time of consultation, her examination showed that the range of motion of the right knee joint was limited (from 0 to 90°), the femoral tibial angle measurement showed that the valgus deformity was 14°, severe pain, and the analgesic gait gradually deteriorated due to the following reasons. Short limbs. These deformities, including pseudoarthropathy, are consistent with bone deformities previously described in patients diagnosed with NF. 5 According to the Kyle Glenn-Lawrence (KL) classification, based on the results of radiography and physical examination, she was diagnosed with grade 4 OA (Figure 1). Due to the pain, her walking distance was restricted. Passive range of motion studies have shown that significant hyperextension (-10°) is consistent with an increased risk of dislocation. Physical examination also revealed that she had peroneal nerve palsy and milk coffee spots throughout her body, the latter indicating advanced NF. About 50 years ago, she used a tibial graft for fibula bone grafting; therefore, only a limited amount of living bone was left to support the successful implantation of the prosthesis. Since there is not enough living bone to support the ready-made intramedullary stem for total knee arthroplasty (TKA; Figure 2), our initial plan was to perform a bicompartmental knee arthroplasty (BKA). In addition, as part of our hospital's preoperative procedures, we performed bone density testing. This assessment showed that the femoral bone density was 0.525 g/cm3, which confirmed our decision to avoid the use of TKA because the quality of the available bone mass is unlikely to be sufficient to support adequate fixation of the larger implants required for this procedure. In view of the differences in anatomy and assessment of soft tissue conditions, magnetic resonance imaging (MRI) was performed to provide maximum visualization of the lesion (Figure 2). Although the dual-compartment knee implant was templated, the cartilage inside the joint was found intact on the coronary MRI scan, so there are contraindications to this surgery (Figure 2). Other radiological studies have shown that this patient has femoral and tibial insufficiency, and the amount of bone that can be used to locate implants that require tibial stems is significantly reduced. Since this patient also showed osteogenesis problems caused by NF, the purpose of planning all procedures was to limit the extent of tissue damage. With this in mind, we believe that single-compartment knee arthroplasty (UKA) is a minimally invasive surgery that can be used to successfully improve her OA symptoms. Discussed with the patient the lateral UKA used to fix the valgus deformity as a way to fully relieve the pain caused by the contact between the lateral bone and the bone and solve the problem of hyperextension. The patient agrees with this course of action. The focus of the preoperative plan is to solve the problems related to bone-to-bone contact and the repair of valgus deformities, with the goal of improving the stability of the knee joint. The range of motion was verified before the operation, and the contact points of the femur and tibia were drawn in the entire range of motion to determine the degree of anteversion. Unfortunately, the size of the anterior bevel prevents the use of implants of a desirable size in consideration of the size of the patient's tibia. We are also aware of the increased risk of dislocation in patients with NF due to characteristic joint hypermobility and soft tissue problems in areas such as the skin, meniscus, and muscle tissue. 6 Figure 1 (A) The X-ray of the right leg recorded severe bone-to-bone contact and bone bruises. (B) Lateral X-ray of the right knee, recording severe anterior hyperextension. (C) Anterior and posterior X-rays recording the degree of limb shortening. (D) Three-dimensional computed tomography (CT) scan to record tibial deformities and osteoarthritis. Figure 2 (A) T2-weighted coronary MRI shows the soft tissue of the right knee and shows isolated osteoarthritis on the outside. (B) The TKA implant template process showed that there was insufficient living bone to support the implant.
Figure 1 (A) X-ray of the right leg, recording severe bone-to-bone contact and bone bruises. (B) Lateral radiograph of the right knee, recording severe anterior hyperextension. (C) Anterior and posterior X-rays recording the degree of limb shortening. (D) Three-dimensional computed tomography (CT) scan to record tibial deformities and osteoarthritis.
Figure 2 (A) T2-weighted coronary MRI shows the soft tissue of the right knee and shows isolated osteoarthritis on the outside. (B) The TKA implant template process showed that there was insufficient living bone to support the implant.
During the operation, the surrounding tissue was debrided and large fragments were removed from the joint space. Visual inspection of the knee joint confirmed the diagnosis of isolated lateral OA with intact medial joints (Figure 3). Insert the femoral single-compartment knee system (Physica ZUK; size D) implant and 29 mm × 50 mm tibial implant (Zimmer®). Perioperative X-rays showed that although the test implant was slightly larger than ideal, it confirmed the synchronized soft tissue balance of the knee joint (Figure 4). Unfortunately, because there is no customized implant, there is still space between the femoral implant and the femoral condyle. Figure 3 (A) A perioperative photograph recording the degree of damage to the lateral cartilage of the right knee. (B) The resected part of the proximal tibia, the size is approximately 40 × 30 × 20 mm. (C) Place the test implant with the smallest usable polyethylene gasket insert. (D) As shown, the final UKA implant with cement and polyethylene inserts. Figure 4 Perioperative X-ray photographs of the test implant taken from the front and back direction when (A) stretched and (B) from the lateral direction when flexed; please note the visible gap between the femoral condyle and the implant in the posterior image.
Figure 3 (A) A perioperative photograph recording the degree of damage to the lateral cartilage of the right knee. (B) The resected part of the proximal tibia, the size is approximately 40 × 30 × 20 mm. (C) Place the test implant with the smallest usable polyethylene gasket insert. (D) As shown, the final UKA implant with cement and polyethylene inserts.
Figure 4 Perioperative X-rays of the test implant taken from the front and back direction when (A) stretched and (B) from the lateral direction when flexed; please note the visible gap between the femoral condyle and the implant in the posterior image.
Before the final fixation, a lot of irrigation is performed on the joint area to promote the penetration of bone cement into the femur and tibia. The final implant is then inserted into the small holes drilled in the tibia and femur, which also promotes the adhesion of the bone cement. Cement was molded to fill the gaps observed during the trial implantation (Figure 3).
Postoperative imaging and physical examination showed that the anterior slope of the tibia was repaired, and the valgus deformity was reduced from the preoperatively determined 14° to 5° (Figure 5). The patient is able to move on the ground within 24 hours after the operation is completed. However, the patient developed an inversion thrust and continued to require epidural analgesia within 48 hours after surgery. The rehabilitation plan includes the scope of auxiliary activities and some weight-bearing walking exercises. The patient showed a myopathy gait; this was considered acceptable given her preexisting musculoskeletal condition. One week after the operation, the patient continued to walk with the help of two crutches and knee pads. She reported soreness after walking about 20 meters; this was attributed to muscle stiffness before surgery (Video 1). The range of motion was extended from 0° to 110°; this represented a significant improvement in her preoperative range of 0 to 90°. Due to the pre-existing peroneal nerve palsy, movement of the ankle joint was limited, and slight pain occurred after the operation. The most significant functional gains of lateral UKA surgery are the improvement of knee joint alignment and the reduction of valgus deformity. Both of these modifications help to significantly improve the patient's ability to walk. Figure 5 (A) The anteroposterior and (B) lateral postoperative X-rays of the final UKA implant, recording the correction of the anterior slope. The AP film showed that the valgus deformity was resolved after the operation (C).
Figure 5 (A) The anteroposterior and (B) lateral postoperative X-rays of the final UKA implant, recording the correction of the anterior slope. The AP film showed that the valgus deformity was resolved after the operation (C).
Two weeks after the operation, the patient fell and caused a stress fracture of the tibial plateau. The lesion was diagnosed as an oblique fracture of the proximal tibia. This is most likely due to a mismatch between the implant and the patient's specific mechanical physiology, which may lead to overcutting of the sagittal plane. There is no displacement of the tibial UKA component (Figure 6). Three days after the fracture, a surgical operation involving a locking plate is planned. The anterolateral plate (ALPS®) of the distal tibia with nine holes was inverted to successfully fix the fracture. Eight locking cortical screws were inserted; postoperative imaging recorded sufficient fixation and support (Figure 6). Given the high risk of dislocation, continuous passive exercise therapy is contraindicated. Within five days after the second operation, the patient reported only mild pain and was able to successfully recover to improve her range of motion. We have noticed that due to the continuing impact of the COVID-19 pandemic, her participation in the standard rehabilitation program has been interrupted. This is unfortunate, because adequate postoperative rehabilitation is essential to recovery. In the first two months after inserting the locking plate, the patient was provided with a fixed knee brace to stabilize her leg. As the COVID-19 pandemic in the area was fully controlled at the time, patients were able to follow a rehabilitation plan, which included passive and active progressive exercises, partial weight-bearing walking programs, and aimed at controlling pain and swelling. Starting from the first week after surgery, the patient adopted a partial weight-bearing walking program (starting at 30%, gradually increasing to 100% body weight every week). During the two-month postoperative examination, the patient was able to walk with weight without assistance (Figure 7). Four months after the operation, the patient reported a significant improvement in pain and range of motion. The patient resumed activities of daily living without the need for knee pads or knee pads (Video 2). Radiographic images showed the formation of callus at the fracture site, indicating the formation of new bone. We plan to follow this patient for a longer period of time to control pain and swelling and maintain improved range of motion and weight-bearing capacity. However, the overall impact of COVID-19 limits the extent to which we can follow this patient after a five-month examination. Nevertheless, the patient still plans to continue to implement the prescribed rehabilitation plan. The patient underwent a 7-month postoperative examination and reported some residual pain. She used the prescribed analgesic regimen to effectively control the pain. She reports that she can walk most days and can perform daily activities without difficulty. On some days, she noticed some instability in the knee joint, which may be caused by postoperative fractures. Further radiological studies showed that the fracture had healed properly, and her physical examination recorded proper knee alignment. Figure 6 Postoperative (A) anteroposterior and (B) lateral tibial plateau lesions, diagnosed as an oblique fracture of the proximal tibia. (C) Postoperative anteroposterior X-ray of the locking plate of the distal tibia showing sufficient fixation. (D) Lateral postoperative X-ray of the locking plate of the distal tibia showing adequate fixation. Figure 7 (A) Anterior and posterior and (B) lateral X-rays at five months postoperatively showing the formation of callus at the fracture site, indicating the formation of new bone. Shown are images of the right knee in (C) flexion and (D) extension. The range of motion is improved and hyperextension is corrected.
Figure 6 Postoperative (A) anteroposterior and (B) lateral tibial plateau lesions, diagnosed as an oblique fracture of the proximal tibia. (C) Postoperative anteroposterior X-ray of the locking plate of the distal tibia showing sufficient fixation. (D) Lateral postoperative X-ray of the locking plate of the distal tibia showing adequate fixation.
Figure 7 (A) Anterior and posterior and (B) lateral X-rays at five months postoperatively showing the formation of callus at the fracture site, indicating the formation of new bone. Shown are images of the right knee in (C) flexion and (D) extension. The range of motion is improved and hyperextension is corrected.
Although the patient was able to walk down the ground before the UKA surgery, she relied on external support and experienced great pain due to osteoarthritis and poor knee alignment. The contraindications of traditional TKA outweigh the benefits that might be obtained in this case. UKA seems to be a more appropriate solution to the pain caused by bone-to-bone contact and valgus deformity. UKA surgery is less invasive, maintains the kinematics of the knee, preserves more bone, and facilitates easier revision surgery if necessary.
Due to the unique complexity associated with this patient, the decision to implement UKA is controversial. However, these treatments have significantly improved the quality of life of patients. The results are quantitatively evaluated by the Knee Injury and Osteoarthritis Outcome Score (KOOS), which is included in the supplementary file (Table S1). An increase of 8-10 points in the total KOOS score has been clearly identified as a clinically significant improvement. Our patient's response to treatment was an increase of 23.2 points in KOOS. This finding indicates that patients benefit greatly from a complete treatment plan. Specifically, areas reported by patients have improved, including but not limited to pain reduction, stiffness reduction, mobility improvement, and quality of life.
UKA is a mature isolated OA intervention. Because UKA is less invasive than TKA, surgeons and their patients prefer this method. Patients with multiple comorbidities usually prefer a less invasive method because it can reduce the risk of other complications and intractable pain. In this patient, reducing pain and avoiding tissue damage were the two most important factors that led to the choice of UKA over TKA. Although the expected surgical outcome (repair of valgus deformity and anteversion) was achieved, this case illustrates a major obstacle related to NF because of a postoperative fracture. In view of the increasing prevalence of diseases that promote joint damage, including osteoporosis, prosthetic joints, obesity, and limb deformities, the problems associated with off-the-shelf implants have become clear. Most notably, due to changes in the condition of bones and adjacent soft tissues, off-the-shelf implants are not suitable for all patients. Recent reports indicate that 9-14% of patients diagnosed with congenital false joints may eventually undergo amputation due to disease complications and the lack of currently available treatment options. 7,8 Our case clearly illustrates the challenging aspects of treating patients with this method of disorder. Compared with TKA, this is a bigger problem for patients receiving UKA, because the former involves only minimal damage to the condyle surface and does not involve removal of the anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL). In this case, TKA was not performed due to the continuous viability of ACL, complete medial cartilage, and lack of bone mass to obtain a suitable TKA implant for this patient. During the template making process, we found that the implant protrudes from the surface of the tibia, increasing the risk of fracture; even for those implants with the smallest available stem size. Therefore, UKA is considered more suitable for this patient. However, even with this improved procedure, too large implants can cause tibial carina fractures. Because the implant is too large, the surface of the tibia is gradually degraded, making the surrounding bones more likely to fracture. Fractures of the tibial plateau may cause bone fragmentation and soft tissue damage.
We solved this problem with a second procedure involving the use of a locking board. The results of previous studies have shown that the locking plate and screw system helps to adequately fix the fracture and limit the possibility of changes in the position of the bone segment. 9 Our patient showed the same range of motion as recorded in the 48 minutes before the onset of OA symptoms a few hours after surgery. In addition, when designing a rehabilitation plan, the deformity of the tibia caused by the false joint is a big problem, because the weight-bearing exercise may put a lot of shear stress on the degenerated tibia. In this case, although both ACL and PCL are elongated, both the medial collateral ligament and the lateral collateral ligament can work normally; therefore, the right knee has sufficient stability. We also noticed that the application of bone cement is critical to the success of the operation, because the special characteristics of the patient’s knee do not fully meet the assumptions of the implant designer. Cases such as these illustrate the need for accessible custom-installed implants that can be designed to fit the joint surfaces of individual patients in a more precise manner. As shown in the figure, the use of inappropriate industry standard implant sizes may increase the risk of postoperative complications, including continued degeneration of surrounding tissues. The ideal device for this patient is the redesigned hinged TKA implant, which can be connected to the tibia by a side locking plate instead of a stem. We believe that custom implants are necessary and should be specially provided because such cases are rare. The purpose of customized patient-specific implants is to provide treatment options for rare cases and patients who cannot tolerate traditional implantation techniques. We firmly believe that obtaining a customized implant will improve the postoperative outlook for this patient. Interestingly, considering these deformities and the risk of postoperative complications may be one of the main reasons for using amputation as the main treatment option for these patients. 8 Despite the consideration of amputation, our patient has a long time to learn to adapt to her shortened limb history; therefore, we do not want to perform drastic procedures that would cause drastic changes in her overall balance.
Knee hyperextension associated with increased anterior tilt of the tibia is similar to knee kyphosis; the latter condition is usually resolved by osteotomy or arthroplasty using rotating hinge implants. 10 Although we can use rotary hinge implants, tibial insufficiency, fracture history, and low levels of available bone indicate that this type of device will not work for this patient. Knee varus deformity is uncommon, and it is reported that less than 1% of patients undergoing knee arthroplasty. 11 In our case, these findings led us to choose joint replacement and osteotomy as the preferred treatment options, because the size and setting of the implant may be used to correct anteversion. However, the additional conditions associated with NF add to the more challenging nature of the case. In this particular case, the condition of the surrounding soft tissue is conducive to the rotation and fixation of the distal tibial plate; we realize that this is not always the case. Considering that NF patients may not tolerate many more traditional treatment options, every effort should be made to avoid complications. 12 When determining the best treatment plan, surgeons and implant manufacturers need to recognize the possibility of postoperative fractures due to improper implants. Actions for individual patients. The priority of focusing on specific aspects of an individual’s condition is also important. For example, in some cases, people may prioritize the effects of limb shortening rather than those related to hyperextension. In contrast, in our case, the first task is to address the effects of osteoarthritis and hyperextension. Therefore, minimally invasive methods are the preferred treatment options. In summary, our findings emphasize the fact that the orthopedic performance of NF poses a major challenge for orthopedic surgeons. In this case, the complexities associated with the multiple complications of NF require careful planning and specific preventive measures. Various patient-specific treatment options should be designed and evaluated before surgery. Although implants customized for rare and highly complex cases may help improve patient prospects, we understand that these resources are costly and may not be available in all hospitals. However, we firmly believe that the "gold standard" for these cases is patient-specific treatment. Physicians and surgeons should work with patients to focus on the issues of greatest concern that can be treated with available resources. Although we understand that due to the nature and complexity of this particular patient, the procedure we designed for this case may not be fully generalized, but our experience emphasizes how the use of traditional resources to develop unconventional methods can ultimately improve the quality of life. In this complex situation, effective communication with patients and discussions with multiple clinicians are essential, because these steps will help us predict complications and determine the strategy that produces the best results.
NF, neurofibromatosis; OA, osteoarthritis; ACL, anterior cruciate ligament; PCL, posterior cruciate ligament; UKA, single-compartment knee replacement; TKA, total knee replacement; BKA, double-compartment knee replacement ; MRI, magnetic resonance imaging; CT, computer tomography; KOOS, knee joint injury and osteoarthritis result score.
The patient’s informed consent was obtained for publication.
The author would like to thank the Medical Journal Editor (MJE) for assisting in editing our manuscript.
This study was approved by the Edogawa Hospital Review Committee. The author has not received financial support for the research, authorship, and/or publication of this article.
The author declares that there is no potential conflict of interest.
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