Journal of Orthopaedic Diseases and Traumatology

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 4  |  Issue : 3  |  Page : 101--106

Proximal fibular osteotomy - a novel technique for surgical intervention in knee osteoarthritis and its application in the Indian scenario: A prospective study


Ritwika Nandi1, Mahboobur Rahman2, Pinaki Das3, Sujit Narayan Nandi1,  
1 Department of Orthopaedics, Nil Ratan Sarkar Medical College and Hospital, Kolkata, West Bengal, India
2 Department of Orthopaedics, Raiganj Government Medical College and Hospital, Raiganj, West Bengal, India
3 Department of Orthopaedics, Institute of Post Graduate Medical Education and Research and Seth Sukhlal Karni Memorial Hospital, Kolkata, West Bengal, India

Correspondence Address:
Dr. Pinaki Das
B 1512, Sector 6, CDA, Cuttack - 753 014, Odisha
India

Abstract

Background: Knee osteoarthritis is a significant cause of functional restriction among the Indian population. In the initial stages when patients present with isolated medial compartment changes, the surgical options in the inventory are few. The scarcity of a simple yet cost-effective procedure has contributed to the growing popularity of isolated proximal fibular osteotomy (PFO) since its inception. This study aims to evaluate the outcome among patients who underwent PFO for symptomatic knee osteoarthritis. Materials and Methods: Fifty patients with medial unicompartmental osteoarthritis of the knee were treated with PFO from December 2017 to December 2020. Patient particulars and intra-operative parameters were recorded. The postintervention functional outcome was evaluated by comparing the preoperative Oxford Knee Score (OKS) with that reported postoperatively. Results: The mean age of the patients included in the study was 48.20 years, with a male: Female ratio of 1.8:1. Sixty-eight percent cases presented with Kellgren–Lawrence Stage III. The patients were followed for a mean of 18.18 months after the procedure. The preoperative, 1-month, 2-month, and 6-month OKS were 24.76 ± 2.63, 33.34 ± 3.84, 39.36 ± 4.65, and 43.02 ± 4.66, respectively. At 6 months postsurgery, 82% of patients were in the satisfactory functional score range (40–48). The most commonly observed complication was superficial peroneal nerve palsy. Conclusion: Despite the simple technique, PFO has been associated with good outcomes and lesser complications. Selection of patients and placement of the osteotomy site are crucial for the success of the procedure. The present study revealed that patients irrespective of their age, gender, or stage of the disease would benefit from the procedure.



How to cite this article:
Nandi R, Rahman M, Das P, Nandi SN. Proximal fibular osteotomy - a novel technique for surgical intervention in knee osteoarthritis and its application in the Indian scenario: A prospective study.J Orthop Dis Traumatol 2021;4:101-106


How to cite this URL:
Nandi R, Rahman M, Das P, Nandi SN. Proximal fibular osteotomy - a novel technique for surgical intervention in knee osteoarthritis and its application in the Indian scenario: A prospective study. J Orthop Dis Traumatol [serial online] 2021 [cited 2022 May 24 ];4:101-106
Available from: https://www.jodt.org/text.asp?2021/4/3/101/332945


Full Text



 Introduction



Knee osteoarthritis has an incidence of 28.7% in the Indian Subcontinent.[1] It can potentially involve all compartments of the knee joint, progressing with age over one to two decades causing significant morbidity. Indian population demonstrates a propensity for the development of varus deformity with age.[2] Frequently, during the initial stages of presentation, patients are diagnosed with isolated medial compartment involvement, which later progress to bi- or tri-compartmental osteoarthritis.[2] Patients with comparable structural changes often present with varying functional impairments, depending on additional factors such as lifestyle, fitness, personality, and occupational aspirations.[3]

The management of osteoarthritis is based on the individual patient's requirements, economic status, modifiable risk factors, and stage of the disease. Initial management is invariably a combination of different conservative modalities including lifestyle modifications, physiotherapy, pharmacotherapy, orthotic devices, and intra-articular injections. However, these often provide only transient pain relief, failing to address the underlying pathology.

Symptomatic patients often require surgical intervention. The surgical options available for the management of medial unicompartmental osteoarthritis of the knee are limited to proximal fibular osteotomy (PFO), high tibial osteotomy, and unicondylar knee replacement.[4]

Osteotomy procedures intend to redistribute load to areas with less severe joint damage, to help alleviate patient symptoms and correct the deformity, hence, delaying further degradation. High tibial osteotomy (HTO), despite being widely implemented, requires a prolonged period of immobilization till union at the osteotomy site. It presents the surgeon with technical difficulty during subsequent arthroplasty. PFO has been introduced in the last decade as an alternative intervention.

Many theories have been proposed to explain the mechanism of action. The most commonly accepted is the “theory of differential settlement.” The term “settlement,” borrowed from the field of architecture, was used to describe the progressive sinking of any construction under load. The lateral tibial plateau, which is supported by the fibula is not allowed to settle, unlike the medial side, resulting in the varus deformity.[5],[6] The reinforcing fibular support when removed, allows uniform settling of both compartments reducing the deformity.[7] Another rationale is the “too many cortices theory,” where the imbalance in load sharing is due to the additional structural support provided by the fibular cortices.[8] The coronal tibiofemoral subluxation or slippage in a varus knee is also considered to further increase the deformity. Distalization of the fibular head and the redirected ground reaction force are also thought to influence the outcome.[5],[9]

In this study, 50 patients diagnosed with medial unicompartmental osteoarthritis of the knee were treated with PFO. The study aims to assess the improvement in the functional status and the complications encountered in them.

 Materials and Methods



The study was conducted in a tertiary care center in eastern India. Before the commencement of the study, ethical approval was obtained from the institutional ethical committee, and written informed consent was obtained from every patient.

The study population constituted of patients presenting to the Out-Patient Department with medial uni-compartmental osteoarthritis of the knee joint, from December 2017 to December 2020. All the patients included were above 18 years of age, who gave consent for the surgery and completed 6 months of postoperative follow-up after PFO.

The patients who had advanced knee osteoarthritis, bi-or tri-compartmental disease, congenital lower limb deformity, fixed flexion deformity >15°, rheumatoid or posttraumatic arthritis, joint infection, previous meniscal injuries, and those unwilling or unfit for surgery (American Society of Anesthesiologists score of more than three) were excluded from the study. The radiological staging of the disease was done according to the Kellgren and Lawrence Classification.[10]

All the patients were examined clinically before being subjected to radiological investigations. Weight-bearing radiographs of both knee joints were obtained in AP view. Their demographic details, affected side, staging of the disease and preoperative Oxford Knee Score (OKS) were documented. The surgical plan and the possible alternatives were explained to the patients and informed consent was taken. OKS Questionnaire[11] was used to assess the patient's functional status at different time intervals.

The patients underwent routine preanesthetic check-ups before they were planned for surgery. Regional anesthesia was preferred. Patients were positioned supine on the radiolucent operating table. The intended limb was draped from mid-thigh to just above the ankle. A rolled-up towel was placed below the knee to keep it flexed at 30°. Pneumatic tourniquet was used in all cases as it decreased the intraoperative blood loss, reducing the operation time. The level of the incision and osteotomy was planned preoperatively based on the length of the fibula. The osteotomy was performed at the junction of proximal 1/5th and distal 4/5th of the fibula [Figure 1]a, [Figure 1]b, [Figure 1]c.{Figure 1}

A 5–7 cm incision was applied over the posterolateral aspect of the fibula and a plane was developed between peroneus longus and soleus. Osteotomy site was marked with drill holes and the distance from the fibular head was checked under fluoroscopy [Figure 2]a and [Figure 2]b. The osteotomy was performed with a narrow blade oscillating power saw and an osteotome and mallet [Figure 2c]. One to two cm of the bone fragment was removed. Wound was closed after achieving homeostasis. Compression dressing was applied.{Figure 2}

Postoperatively, all patients were given prophylactic intravenous antibiotics after skin testing for 24 h, followed by oral antibiotics for 5 days. The patients were started on knee range of motion (ROM) as soon as the effects of anesthesia weaned off and weight-bearing was allowed as early as tolerated.

The total duration of surgery (time till tourniquet deflation) and the number of days of hospital admission were documented. Postoperative standing AP and lateral radiographs were obtained [Figure 3]a and [Figure 3]b. The stitches were removed on postoperative day 14. Patients were followed up every 4 weeks, clinically and radiologically. At each follow-up, their functional status was assessed using the OKS Questionnaire. Complications were noted. The OKS at 1-month, 2-month, and 6-month and the total duration of follow-up were documented.{Figure 3}

Statistical analysis was performed with the help of Epi Info™ 7.2.2.2. Descriptive statistical analysis was performed to calculate the means with corresponding standard deviations (SD). Test of proportion was used to find the Standard Normal Deviate (Z) to compare the different proportions and Chi-square (x2) test was performed to find the associations.

One-way analysis of variance (ANOVA) followed by post hoc Tukey's test was performed with the help of critical difference at 5% and 1% level of significance to compare the mean values of more than two groups. P < 0.05 was taken to be statistically significant.

 Results



During the study period, 220 patients presented with knee osteoarthritis, of which 70 patients had isolated involvement of the medial compartment. Ten patients did not give consent for surgery and ten were lost to follow-up. Finally, 50 patients were included in the study group.

The mean age of the patients was 48.20 years (SD 6.52), ranging between 34 and 60 years. Most of the patients (88.0%) were of age ≥40 years, which was significantly higher than other age group (Z = 10.74; P < 0.0001). Thirty-two patients were male and the rest 18 were female. The ratio of male and female (Male:Female) was 1.8:1. Test of proportion showed that the proportion of males (80.0%) was significantly higher than that of females (20.0%) (Z = 3.95; P < 0.001). The prevalence was equally distributed among males and females over all age groups (P = 0.64).

About 68.0% of the patients in the study presented with Stage-III of the disease which was significantly higher than other stages (Z = 3.84; P < 0.0001). There was no predilection of left or right limb involvement (Z = 0.01; P = 0.99).

The mean duration of the surgery was 23.91 min (range of 15-41, SD of 6.79). The average hospital stay was 2.7 days (SD 0.76). The patients were followed up for 9–32 months (average– 18.18 months, SD-6.75).

The functional status was assessed using the OKS both preoperatively and during the subsequent visits following the surgery. The preoperative, 1-month, 2-month, and 6-month OKS were 24.76 (SD 2.63, Range 21–32), 33.34 (SD 3.84, Range 23–40), 39.36 (SD 4.65, Range 28–48), and 43.02 (SD 4.66, Range 29–48), respectively [Figure 4]. One way ANOVA test showed that there was a significant difference in mean OKS of the patients at different time intervals (F3, 95 = 195.78; P < 0.0001). Tukey's test demonstrated that the mean OKS of the patients improved significantly after surgery at different time intervals (P < 0.01).{Figure 4}

In our study, majority of the patients, i.e., 94% of patients were in the moderate-to-severe functional group, i.e., OKS of 21–30, preoperatively. At 6 months postsurgery, 82% of patients were in the satisfactory functional score (40–48). However, 4% of patients remained in the “moderate-severe” functional group, requiring further interventions [Table 1].{Table 1}

The mean difference of postintervention OKS with respect to the preoperative OKS in different time intervals for different stages, gender, and age of the patient was found to be independent of each other [Figure 5]. t-test demonstrated a statistically nonsignificant result. Thus, the functional improvement attained was not associated with the stage, gender, or age of the patient.{Figure 5}

The complications encountered are documented in [Table 2]. The most commonly observed complication was superficial peroneal nerve palsy. Four patients complained of tingling and numbness over the anterolateral calf and dorsum of the foot. They were managed conservatively and the symptoms subsided within 8 months after the surgery. Two patients reported persistent pain and functional restrictions. They underwent arthroplasty for the above at 17 and 23 months following the primary surgery, respectively.{Table 2}

 Discussion



Persistent, debilitating knee pain caused by osteoarthritis is among the most commonly encountered problems in any orthopedic practice. Based on the degree of hindrance to the activities of daily living, vocation, and mental health, the management of the disease is adapted to the individual requirements. In patients presenting with osteoarthritis limited to the medial compartment, surgical options are offered once the medical treatment fails to provide relief. Strict adherence to the prerequisites for HTO, in patients with high functional demand, results in excellent outcomes. However, should the need for arthroplasty arise, it is associated with a high incidence of complications.[12] Unicondylar knee arthroplasty (UKA) has also reported excellent outcomes, though its application is restricted in the current patient demographics due to the cost retrains.[13] The dearth of a simple, less invasive albeit effective procedure has led to the inception of PFO.

In the present study, fifty patients with unicompartmental osteoarthritis of the knee (medial compartment) were treated surgically with PFO. Determination of the osteotomy site was considered the most critical step of the procedure. Proximal positioning endangers the peroneal nerve, which is intricately related to the bone. If the level selected is too distal in placement, the mechanical axis would be unaffected by the surgery.[5] Osteotomy and partial excision of the fibula have been done commonly for various orthopedics indications. After PFO, the proximal fibular segment becomes free from the constraints of the tibio-fibular syndesmosis and distal fibula, leading to a relative increase of ROM of the proximal tibiofibular joint. The muscles attached to the fibular head applies distal traction on it, resulting in decreased lateral joint space to counteract the varus deformity. Tibiofibular arthritis, which restricts this motion, could have an adverse effect on the outcome of the procedure.[14] The proximal fibular shaft, i.e., 40–60 mm distal to the fibular tubercle is considered safe to avoid damage to the motor branches of the deep peroneal nerve.[15] Yang et al. concluded that the ideal distance of the fibular osteotomy site should be between 6 and 10 centimeters from the tip of the fibula, depending upon the height of the patient.[16] The mean duration of surgery reported by Ahmed et al.[17] was 23.80 ± 3.05 min, comparable to the present study which reports 24.76 ± 2.63 min. The operative time is considerably lesser than that reported for HTO[18] and UKA.[19]

The patients were selected by simple random sampling and the outcome was assessed based on the preoperative and postoperative OKS.[11] It is a patient-reported outcome measure developed initially in 1996 to specifically evaluate knee pain and function. Since then, its scope has broadened to include use in other joint disorders and to evaluate surgical treatments.[20]

In the present study, unicompartmental osteoarthritis of the knee was more prevalent after the fourth decade of life. This was in accordance with the fact that there is an increase in the incidence of osteoarthritis with age.[21] Elderly patients often have advanced disease, involving two or three compartments. Hence, the incidence also falls with age as only those patients with unicompartmental knee osteoarthritis were included in the study. The current study concludes that male patients were at a higher risk of developing medial unicompartmental osteoarthritis of the knee than females, contradicting the opinion prevalent in the existing literature.[1] It was a consequence of male patients being more active in seeking consultation for knee pain which would hamper their outdoor activities and work. Among the operated patients most belonged to Stage III (32 out of 50) as more often the patients with Stage II opted for nonoperative management unless the symptoms affected their activities of daily living significantly.

The mean OKS increased by 34.62% at 1-month postsurgery from its preoperative value. At 2-month and 6-month postintervention, the OKS reported an improvement of 58.97% and 73.74%, respectively. Utomo et al.[22] and Ahmed et al.[17] also reported the functional outcomes in their study by implementing the OKS questionnaire. The comparison of their outcome with that obtained in the present study is tabulated in [Table 3]. However, in both of these studies, the outcome was reported in the immediate postoperative period.{Table 3}

The present study concludes that patients who underwent the surgery reported significant improvements in their functional status and the improvements were seen irrespective of their age, sex, or stage of the disease. These nonmodifiable factors do not preclude a good outcome.

Pancorbo et al. evaluated 116 knees, which underwent PFO and reported complications, i.e., neuropraxia, hematoma, infections, in 9.4% of cases.[23] In the present study, 8% of patients developed peroneal nerve palsy and 4% reported a lack of satisfactory functional outcome.

Rai et al. reported pain relief in all patients along with the recordable mechanical axis realignment.[24] In the present study, one major limitation was the inability to obtain serial whole limb orthoscannogram. Hence, any postinterventional changes in the radiological parameters could not be sufficiently documented. Another drawback was the lack of a control group. A multicentric study with larger sample size and longer follow-up period is required to further evaluate the procedure. Any long-term impact on the biomechanics of the hip or ankle has not yet been evaluated.

 Conclusion



PFO appears to be an attractive option for medial compartmental OA of the knee. The current literature is limited to small case series and reports good outcomes with pain including correcting the varus deformity in medial OA. If subsequent arthroplasty is required, no hindrance would be encountered by the surgeon. Selection of patients and placement of the osteotomy site are crucial for the success of the procedure.

Consent to participate

Written informed consent was obtained from the patient for this procedure. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Consent for publication

Written informed consent was obtained from the patients for publication of this study and accompanying images.

Acknowledgments

We would like to acknowledge all the faculty members and junior residents who helped relentlessly in conducting our research work.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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