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Risk Factors in the Development of Knee Osteoarthritis in Sokoto, North West, Nigeria

Muhammad Oboirien, Stephen Patrick Agbo, Lukman Olalekan Ajiboye

Muhammad Oboirien, Stephen Patrick Agbo, Lukman Olalekan Ajiboye, Department of Surgery, Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria

Conflict-of-interest statement: The author(s) declare(s) that there is no conflict of interest regarding the publication of this paper.

Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

Correspondence to: Muhammad Oboirien, Department of Surgery, Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria.
Email: moboirien@yahoo.com
Telephone: +2348067893799

Received: February 22, 2018
Revised: April 20, 2018
Accepted: April 23 2018
Published online: April 28, 2018

ABSTRACT

AIM: We aim to determine risks factors associated with degenerative knee osteoarthritis in our environment.

METHODS: An audit of patients with clinical and radiological features of Osteoarthritis of the knee was carried at an Orthopaedic clinic in sub-urban region in North west Nigeria between January 2016 and December 2016. Patients with prior history of trauma to the knee were excluded.

RESULTS: There were fifty-nine patients and the age range was between 36 and 83 years with a mean 55.5 ± 11.09 and males were 34% and females were 66% giving a M: F ratio of 1 : 1.9. Bilateral knee affectation was seen in 50.8% and unilateral affectation in 49.2%. Fifty-six percent of patients were housewives while 30.5% were civil servant. Eight-one percent of patients were overweight and obese. Pain was the predominant clinical symptoms with 79.7% and pain and swelling was present in 18.6%. Sixty-four percent of patients have had symptoms with duration of more than 12 months. The relationship between the Body mass index (BMI) with the duration of symptoms, unilateral or bilateral affectation of the knee was not statistically significant p > 0.05. Overweight and obese patients have more severe forms of the disease. Non steroidal anti-inflammatory drug (NSAIDS) was used in 47.5% of cases while in 40.4% of cases intra articular steroid administration was administered in addition to NSAIDS.

CONCLUSION: Increasing age, the female gender and increased BMI are risk factors associated with the development of degenerative knee osteoarthritis.

Key words: Osteoarthritis; Knees; Body mass index

© 2018 The Author(s). Published by ACT Publishing Group Ltd. All rights reserved.

Oboirien M, Agbo SP, Ajiboye LO. Risk Factors in the Development of Knee Osteoarthritis in Sokoto, North West, Nigeria. International Journal of Orthopaedics 2018; 5(2): 905-909 Available from: URL: http://www.ghrnet.org/index.php/ijo/article/view/2258

Introduction

Osteoarthritis (OA) of the knee remains a debilitating condition affecting millions of people worldwide. The prevalence of the disease varies among populations and from region to region. Many hospital-based studies have shown that OA is common in Nigeria, more in females than males and that it affects the knee more than any other joint accounting for 65%-78%[1]. It has also been reported that multiple joint affectations and involvement of joints of the extremities are uncommon among Nigerian patients[1,2]. Knee OA represents a heterogeneous group of conditions resulting in common histopathologic and radiologic changes. Primary Knee OA is a degenerative disorder arising from biochemical breakdown of articular (hyaline) cartilage in the synovial joints. Current view has it that osteoarthritis involves not only the articular cartilage but also the entire joint structure, including the subchondral bone and Synovium[3,4]. Various risks factors including age, genetics, lifestyle and obesity have been implicated in the development of degenerative Knee Osteoarthritis. Hyaline cartilage is avascular, aneural, and alymphatic. It is 95% water and extracellular cartilage matrix and only 5% chondrocytes. Chondrocytes have the longest cell cycle in the body (similar to CNS). We therefore aim to determine risks factors associated with degenerative knee osteoarthritis in our environment.

MATERIALS AND METHODS

An audit of patients with clinical and radiological features of Osteoarthritis of the knee was carried out at an Orthopaedic clinic in North west Nigeria between January 2016 and December 2016. Patients with radiographic evidence of OA but with history of trauma were excluded. The diagnosis of primary knee OA was made from history and physical examination and confirmed with plain film radiographs. Radiographic findings on X-ray needed for diagnosis include joint space narrowing, osteophytes formation, Subchondral sclerosis and subchondral cyst formation. Joint space narrowing as defined by the Ahlbäck classification and the Kellgren and Lawrence system was used to make a radiographic diagnosis and classification. Patients whose radiographs showed peri-articular osteoporosis and erosion were excluded.

RESULTS

There were fifty-nine patients seen with age range of between 36 and 83 years and a mean 55.56 ± 11.09 (Figure 1). Males were 34% and females were 66% giving a M: F ratio of 1 : 1.9 (Figure 2). Bilateral knee affectation was present in 50.8% and unilateral affectation in 49.2% (Figure 3). Fifty-six percent of patients were housewives while 30.5% were civil servants. Others include businessmen (10.2%), Farmers (3.4%) (Figure 4). Pain was the predominant clinical symptoms with 79.7% and pain and swelling was present in 18.6%. The Body mass index (BMI) showed that 55.9% of the study population were obese, 25.4% were overweight and 16.9% having normal weight (Figure 5). Sixty-four percent of patients have had symptoms with duration of more than 12 months with 52.5% of this patients being overweight and obese. Fifty-six percent of obese patients had bilateral knee affectation while unilateral knee affectation was present in 55.1%. Housewives and civil servant were the most obese with 49.1% (Table 1). Overweight and obese patients have more severe forms of the disease (Table 2). The relationship between the Body mass index (BMI) with the duration of symptoms, unilateral or bilateral affectation of the knee and occupation were not statistically significant p > 0.05 (Table 3). Non steroidal anti-inflammatory drug (NSAIDS) was used in all cases while in 50.9% of cases had intra articular steroid and hyaluronic acid administration in addition to NSAIDS. Corrective osteotomy was done in 2% of cases (Figure 6).

Table 1 Crosstabulation of BMI with Occupation.
 OccupationTotal
Civil servantHousewivesFarmerBusiness
BMIUnderweight10001
Normal weight180110
Overweight390315
Obese13162233
  18332659
Chi square df = 1, p = 0.402

Table 2 Crosstabulation of BMI with Kellgren and Lawrence.
 KLTotal
grade 1grade 2grade 3
BMIUnderweight0101
Normal weight36110
Overweight46515
Obese6141333
Total 13271959

Table 3 Cross tabulation of BMI with Symptoms, Duration of symptoms, Affected knee, Occupation
 BMI
Underweight Normal Overweight Obese Total Chi Square P- value
SymptomsPain 191225471.380.241
Swelling 00101
Pain & swelling012811
Duration < 6 months0448160.010.976
6-12 months00055
>12 months16112038
Affected KneeUnilateral 121016290.280.597
Bilateral 0851730
OccupationCivil servant11313180.7030.403
Housewife 0891633
Farmer 00022
Business 01326
Chi-square test showed no significant relationship (p > 0.05) between BMI with duration of symptoms, affected knee and occupation

Figure 1 Age distribution of patients.

Figure 1 Sex distribution of patients.

Figure 3 Knee affectation.

Figure 4 Occupation of patients.

Figure 5 Weight distribution of patients.

Figure 6 Treatment offered to patients.

DISCUSSION

Primary knee osteoarthritis is thought to be idiopathic and it occurs in a previously intact joint and with no initiating factor. The precise etiology of primary knee OA is unknown, but biochemical and biomechanical factors are likely to be important in the etiology and pathogenesis. The mean age of those that were diagnosed with primary OA in our study was 55.5 years which is higher than the average age in other studies. Prevalence rates for both radiographic OA and, to a lesser extent, symptomatic OA rise steeply after age 50 in men and age 40 in women and this probably is a result of cumulative exposure to various risk factors and biologic changes that occur over the years with aging[5]. A cohort of adults (age 56-84) in Malmo, Sweden, shows that the prevalence of radiographic and symptomatic knee osteoarthritis where 25.4% (95% CI = 24.1, 26.1) and 15.4% (95% CI = 14.2, 16.7), respectively[3,6].

Many studies have documented that osteoarthritis risk is greater among females and with increasing age[7,8], and some studies have shown an increased risk with lower socioeconomic status[9] and African American race[10,11]. Our study showed a higher female preponderance as is the case in most studies worldwide. Female are not only at higher risk of OA than men, but they are also prone to have severe OA. Age, sex, hormones have been categorized as constitutional risk factors.

The study also showed that more than half of the patients were full time housewives and civil servants. The culture amongst the people in this part of Nigeria is that outdoor activities of women are restricted hence the sedentary life style. The civil service is another arear where workers are inactive. Physical inactivity leads to weight gain and poor nourishment of the joint. Studies from the Johnston County Osteoarthritis Project however did not show an increase prevalence in those who were less active[12]. Professional Farmers were the list affected in our study. Improve physical activities help to improve muscle strength and tone with recent reviews concluding that muscle weakness may confer risk for knee osteoarthritis onset and progression. The specific role of muscle strength and mass in osteoarthritis structural development and progression is still somewhat unclear, however muscle strength appears to play a role in knee symptoms[13,14].

Obesity is a key person-level risk factor for knee osteoarthritis, increasing the risk three-fold, and evidence suggests that obesity accelerates progression of knee osteoarthritis[3,4,15-17]. Multiple studies have suggested a strong relationship between OA with both overweight and obesity. Obesity is associated with increase incidence of major diseases such as cardiovascular diseases and diabetes mellitus. Elevated BMI is both a systemic and local risk factor for development and progression of knee OA. Increased body weight is believed to increase joint reaction force, which in turn increases wear on cartilage, the so-called intuitive biomechanical theory[17,18]. Forces across the joint increases while walking or physical activities. BMI is known to have a direct effect on severity of OA in varus knees. Overweight women have nearly 4 times the risk of knee OA; for overweight men the risk is 5 times greater and it is estimated that persons in the highest quintile of body weight have up to 10 times the risk of knee OA than those in the lowest quintile. Obesity also causes changes in the density and stiffness of subchondral bone relative to the overlying cartilage and this has been implicated in the development of knee OA[18].

Studies have illustrated evidence for a metabolic/inflammatory pathway between obesity and osteoarthritis. In a cohort study of US women, higher baseline serum leptin was associated with greater odds of severe knee joint damage and in another study of older adults, it was found that almost half of the association between BMI and knee osteoarthritis was explained by leptin levels[19,20]. Studies have supported the beneficial effect of weight loss or maintenance to improve osteoarthritis symptoms, percentage change in weight was significantly associated with changes in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores[18].

Pain was the predominant complaints amongst the patients and duration of more than twelve months was present in most of the patients in our study. Pain of osteoarthritis is insidious in onset with occasional remission with or without medications. The pain experience in knee osteoarthritis in particular is well-recognized as typically transitioning from intermittent weight-bearing pain to a more persistent, chronic pain. The etiology of pain in osteoarthritis is recognized to be multifactorial, with both intra-articular and extra-articular risk factors[21]. Pain results in a vicious cycle of inactivity as it reduces joint mobilisation with resultant stiffness thus worsening the clinical condition. Pain reduces the activities of daily living and for housewives and civil servant, sitting for prolonged period of time with inactivity can lead to obesity. Obesity has been found by several workers to be a modifiable risk factor not only for OA but also for pain. It is believed that mechanical loading on the joint and elaboration of adipokines potentially contributes to pain[22,23].

Other person-level risk factors for primary osteoarthritis that have been documented in literature include social economic status and family history. These factors where however not assessed in our study.

Joint-level risk factors with strong evidence for secondary osteoarthritis risk include injury and occupational joint loading, knee deformities; the associations of injury and joint alignment with osteoarthritis progression are compelling. While it may be true that patients with angular deformities like genu varum and valgum may predispose patients to unusual loading with unicompartmental osteoarthritis, patients with OA can be complicated with with angular deformities[24,25]. Very few patients had angular deformities in our study which were a complication of the disease.

This single center cohort study is limited in scope and study population as some other patients may have been seen in other hospitals.

CONCLUSION

Increasing age, the female gender and increased BMI are risk factors associated with the development of degenerative knee osteoarthritis. Obesity being a modifiable risk factor can be attenuated and housewives in this region need to be engaged in in-door sporting activities to help them keep fit and reduce obesity.

Acknowledgment

We declared no sources of funding for this work and acknowledge the support of the health information record system for the retrieval of patients’ case files

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