Multiple sclerosis (MS) is an autoimmune, inflammatory disorder resulting in demyelination of the central nervous system axons with a wide array of symptoms that encompass everything from subtle numbness and tingling to profound muscle weakness. The pattern of symptoms is often undulating, and as such can present at varying stages. There are roughly 400,000 people in the United States who are affected by MS, with women more commonly affected than men.¹ Although the orthopedic surgeon is not commonly managing the majority of symptoms from MS, there are several issues that are relevant to orthopedists when evaluating a patient with MS who presents with a musculoskeletal complaint. Some of these issues include increased risk of fractures, osteoporosis, increased complications following total joint arthroplasty, difficulty in distinguishing neuropathy from MS symptoms, and lack of improvement following surgical intervention for cervical myelopathy.

Some of the many symptoms patients with MS can have include dizziness, lightheadedness, loss of balance, numbness, and blurred vision, all of
which can lead to a propensity for falls.² Unfortunately, the actual disease process of MS, the immobility associated with MS, low vitamin D levels, as well as some of the treatments for MS (glucocorticoids) can lead to severe osteoporosis.² Although use of glucocorticoids is common in patients with MS, either the use of glucocorticoids or the disease process itself may predispose patients to a higher risk of osteonecrosis.³ Delanois et al reviewed 34 patients who were treated for osteonecrosis of the talus and noted MS as one of the causes. Furthermore, 83% of patients in their study had a history of corticosteroid use, making the combination of MS and steroid use a high risk for osteonecrosis. Patients with MS who present with hip, ankle, shoulder, and other joint pain should be carefully evaluated for osteonecrosis. This evaluation includes radiographs of the involved joint(s) followed by magnetic resonance imaging if the radiographs are negative. This allows early diagnosis of the osteonecrosis, hopefully before the collapse stage, thereby greatly increasing the treatment options for the patient. Once osteonecrosis progresses to the collapse stage, the treatment options become much more limited, so catching this process in the early stages is extremely important.

The combination of increased risk of falls and osteoporosis puts patients with MS at increased risk of fractures, specifically those about the hip.⁴ Bazelier et al used the Danish national registry to compare 11,157 patients with a diagnosis to MS with 57,273 controls without a diagnosis of MS.⁴ The purpose of the study was to report the incidence rates of fracture in patients with MS and stratify these fractures by location, sex, and age. The authors also compared the fracture rates of patients with MS with those of controls to see if a difference existed. The average age of patients with MS was 46.4 years (45.9 for controls), and females made up 65.9% of the MS cohort. Of note, when reviewing the medication lists, patients with MS used significantly more antidepressants, anxiolytics, and anticonvulsants than controls. This is something to keep in mind when prescribing medications to patients with MS to avoid an unwanted medication interaction. Obtaining a thorough medication history can avoid any unnecessary complications. The fracture incidence in patients with MS was 22.84 per 1000 person-years compared with 16.53 per 1000 person-years in controls. This gave an incidence rate ratio for any fracture between patients with MS and controls of 1.40. However, when the fractures were broken down by location, the incidence rate ratio for patients with MS compared with controls was 3.36 for tibia fractures, 6.66 for femur fractures, and 3.20 for hip fractures. Hence, although patients with MS had an increased overall risk for fracture compared with controls, this risk was significantly higher in hip, femur, and tibia fractures. Although fractures about the lower extremity are common, the pelvis can also be fractured in patients with MS. There has been a report of spontaneous bilateral periacetabular fractures in patients with MS necessitating open reduction internal
fixation.⁵ The cause was thought to be a combination of osteoporosis and spasticity. This highlights the fragility of some patients with MS. When a patient with MS complains of bone pain, it is important to investigate that complaint and ensure it is not a fracture.

The increased risk of fracture and osteoporosis associated with MS is concerns not only for patients sustaining fractures in general but also for patients sustaining falls and fractures in the acute postoperative period. Many of the orthopedic surgeries performed require a period of limited weight bearing and use of an assist device. When patients are unsteady on their feet, using an assistive device can be challenging. An inability to adequately progress with therapy may require a longer in-patient hospital stay or a short stay in a rehabilitation center following discharge to make sure the patient is safe. Similarly, osteoporosis is a concern in many orthopedic procedures, as fixation of implants becomes a problem when the patient’s bone is diseased.⁶ This can become particularly relevant when treating ankle fractures, obtaining a good press fit in a total hip arthroplasty, and others.⁶,⁷ In a patient with MS who is undergoing an elective orthopedic procedure, it is prudent to obtain a bone mineral density test to evaluate the degree of osteoporosis in the preoperative period. Furthermore, there may be a role for treating the osteoporosis in these patients before offering them an elective surgery to help increase their chances of a successful outcome.⁸ This may not always be possible, especially in patients who present with a long bone fracture, but should be considered in patients who necessitate elective procedures. Interestingly, there is limited evidence regarding treatment of long bone fractures in patients with MS. One study did show excellent results when treating a patient with MS with a femur fracture using a retrograde nail.⁹ The fracture fixation implant should be tailored to the individual patient and fracture pattern, taking into account bone stock.

Studies have shown that patients with MS have roughly the same risk of developing arthritis as the general population.² Patients with MS may also suffer from spasticity, specifically spasticity of the adductors, which can lead to gait dysfunction, skin irritation, and difficulties with perineal hygiene.¹⁰ This spasticity can be treated using injections of intramuscular botulinum toxin, which has been shown to be effective in increasing passive hip abduction and the space between the knees in patients with MS with adductor spasticity.¹⁰ Aside from the abductor spasticity, patients with MS in need of a total hip arthroplasty (THA) provide a challenge to orthopedic surgeons in regards to operative technique as well as rehabilitation.³ Newman et al performed a review of the National Inpatient Sample (the largest US all-payer database of inpatient admissions) to evaluate
the short-term outcomes following THA in patients with MS. The authors wanted to specifically study patient factors that differed in patients with MS and patients without MS, as well as report patient outcomes (complications, length of hospital stay, etc.) in those who had MS and underwent THA compared with all non-MS patients who underwent THA. They matched the patients with MS who underwent THA to controls without MS who underwent THA in a 1:3 ratio to control for confounding variables.