Expert consensus on the diagnosis and treatment of ankylosing spondylitis in orthopedics
Ankylosing spondylitis (AS) is a connective tissue disease that mainly affects the sacroiliac joints, spinal joints, paravertebral soft tissues and peripheral joints, and may be accompanied by extra-articular manifestations. According to a preliminary survey, the prevalence of AS in China is about 0.3%, and the ratio of men to women is about 2.3:1, with a slow onset and milder disease in women. The age of onset is usually 13-31 years, with a peak age of 20-30 years, and rare after 40 years and before 8 years of age.
AS is a seronegative spondyloarthropathy. The lesion begins in the sacroiliac joint and progresses slowly up the spine or spreads simultaneously down the spine, involving the hip and knee joints bilaterally, but rarely the upper extremity joints. Early pathology is marked by sacroiliac arthritis, and late spinal involvement is typically characterized by “bamboo-like changes.” It usually takes 5-10 years from the first chronic symptoms to diagnosis. The key to controlling the progression of the disease and reducing the disability rate lies in early diagnosis and reasonable and timely treatment.
II. Diagnostic criteria of AS
In recent years, the New York criteria revised in 1984 (Table 1) have been more commonly used for the diagnosis of AS. In 2009, The Assessment of SpondyIArthritis The criteria for the diagnosis of axial spondyloarthropathies (Figure 1), developed by the SpondyIArthritis international Society (ASAS) in 2009, are useful in confirming the diagnosis of AS at an early stage and in determining treatment options.
Confirmation of AS: Any of the radiological criteria plus clinical criteria 1-3 are met. Grade 0, normal; Grade I, suspicious or minimal sacroiliac joint lesions; Grade II, mild abnormality with limited erosion and sclerosis but no change in the joint space; Grade III, significant abnormality with at least one of the following changes: sclerosis of the proximal joint area, narrowing or widening of the joint space, and partial ankylosis; Grade IV, severe abnormality with complete joint ankylosis.
III. Treatment plan for AS
(2) Prevention and correction of deformity: slow down the process of spine and joint destruction, and surgical correction of ankylosis or severe deformity of the spine or large joints such as hip and knee; (3) Improvement of function: maximize the recovery of physical and psychological functions such as spinal mobility, social activity and work ability. (3) Improvement of function
Treatment principle: early stage is based on drug treatment, late stage is based on surgical treatment when ankylosis or severe deformity of large joints such as spine or hip and knee occurs.
(A) Non-surgical treatment
1.Non-pharmacological treatment
(1) Patient education: Provide patients and their family members with regular education about the disease, so that they can establish adequate knowledge of the disease. The long-term treatment plan should also include psychosocial and rehabilitation counseling for patients.
(2) Posture and position: Maintain maximum functional posture during daily activities to prevent spinal and joint deformities. This includes standing with the chest up, abdomen tucked in and eyes looking straight ahead; sitting with the chest upright; sleeping on a hard bed, mostly in the supine position, avoiding positions that promote flexion deformity; sleeping on a low pillow and stopping the use of pillows when the upper thoracic or cervical spine is involved; keeping the large joints of the limbs in a functional position and avoiding non-functional ankylosis.
(3) Functional exercise: Regular physical exercise is the basis for successful AS treatment. Deep breathing and coughing can increase thoracic expansion, strengthen the paravertebral muscles and increase lung capacity, maintain joint mobility, and prevent or reduce disability.
(4) Give necessary physical therapy to painful, inflamed joints or soft tissues.
(5) Pay attention to rest during activity, consume meals rich in calcium, vitamins and nutrients, and eat more fruits. Quit smoking and alcohol.
2.Medication
(1) Non-steroidal anti-inflammatory drugs (NSAIDs): NSAIDs can rapidly improve low back pain and morning stiffness, reduce joint swelling and pain and increase range of motion in AS patients, and can be used as first-line drugs for early or late symptom treatment. Long-term continuous application of NSAIDs can prevent and stop new bone formation in AS compared with on-demand application, especially selective COX-2 inhibitors not only have strong anti-inflammatory effects but also prevent and stop the progression of AS imaging [4]. When prescribing NSAIDs, the discretionary risk of cardiovascular, gastrointestinal and renal impairment needs to be weighed. Compared to non-selective NSAIDs, long-term application of selective COX-2 inhibitors is less likely to cause gastrointestinal damage and has a better total gastrointestinal safety profile.
(2) Salicyclovir: It can improve pain, swelling, and morning stiffness in peripheral joints of AS, and reduce serum lgA levels and other laboratory indicators of activity, but it is less effective for mid-axis symptoms. The recommended dose is 2,0g daily in 2-3 oral doses. Salicyclovir has a slow onset of action, with maximum effect usually occurring within 4-6 weeks of dosing. To compensate for its slow onset of action and weak anti-inflammatory effect, a combination of fast-acting NSAIDs can be used.
(3) Glucocorticoids: Glucocorticoids cannot stop the progression of AS and have large adverse effects. Persistent tendon telangiectasia and persistent synovitis may respond well to local glucocorticoids. Intra-articular glucocorticoid injections are feasible for recalcitrant peripheral arthritis (e.g., knee joint) where systemic medication is not effective, usually no more than 2-3 times per year.
(4) Biologic agents: Biologic agents are a new type of AS control drugs with good anti-inflammatory and disease progression effects. The only biologic agents proven to be effective in the treatment of AS are TNF-α inhibitors [6]. TNF-α inhibitors are characterized by rapid onset of action, significant inhibition of bone destruction, significant efficacy on both mesial and peripheral symptoms, and overall good patient tolerance. Patients who are not satisfied with the efficacy of one TNF-α inhibitor or cannot tolerate it may choose another.
Biologic agents have the potential for injection site reactions or infusion reactions and an increased risk of tuberculosis infection, hepatitis virus activation, and tumors. Etanercept does not cause lysis of immune cells expressing transmembrane TNF, reducing the risk of tuberculosis infection and tumor induction. Screening for tuberculosis and hepatitis, excluding active infection and tumor, should be performed before drug administration, and routine blood tests and liver and kidney function should be reviewed regularly during drug administration.
(ii) Surgical treatment
1.The purpose of surgical treatment
The purpose of AS surgery is to correct the deformity, improve the function and relieve the pain.
2. Indications for surgery
Patients with AS should be considered for spinal orthopedic surgery or joint replacement when they have kyphotic deformity, hip and knee ankylosis, hip and knee pain and restricted movement, and X-ray signs of structural damage. The results of surgery are long-term, stable, and reliable, but patients should be informed preoperatively that the purpose of surgery is to treat severe spinal deformity and joint dysfunction caused by AS, not to treat the AS disease itself [19].
3. Preoperative preparation
(1) Erythrocyte sedimentation rate and C-reactive protein: The erythrocyte sedimentation rate and C-reactive protein of AS patients are generally higher than those of the normal population, which are indicators of disease activity and are not the basis for determining whether surgery can be performed. However, if the preoperative C-reactive protein in AS patients exceeds the normal value several times, the risk of infection after joint replacement is increased.
(2) Osteoporosis: Lack of stress stimulation in the vertebral body after spinal ankylosis leads to osteoporosis, which is very common in AS patients. Preoperative consideration should be given to the difficulties that osteoporosis may cause for firm internal fixation. Osteoporosis is also common after joint ankylosis, and the occurrence of periprosthetic fractures should be guarded against when joint replacement is used.
(3) Respiratory function: AS patients have restricted thoracic expansion and reduced respiratory reserve function. In addition to coughing and sputum training, pulmonary function monitoring should be routinely performed before surgery. For patients under general anesthesia, if the forced expira-tory volume in one second (FEVl) is less than 40% of the expected value, the maximum ventilatory volume/minute (MVV) is less than 50% of the expected value, and the pulmonary function is less than 35%, the patient cannot undergo surgery immediately. If the lung function is < 35%, the patient cannot undergo surgery immediately and must wait for the lung function to improve through training.
(4) Anesthesia: Pre-operative consultation with the anesthesiologist should be conducted. Patients with cervical spine ankylosis may have difficulty in intubating anesthesia and should be prepared for preoperative fiberoptic bronchoscopic tracheal intubation and other T instruments.
(5) Medical drugs: Patients with AS often need to take some medical drugs during the perioperative period, and the need to discontinue the drugs should be treated differently. A balance should be found between reducing surgical complications and maintaining the efficacy of medications to facilitate the postoperative recovery of AS patients.
4.Surgical methods
At present, the common surgical methods include spinal osteotomy, hip replacement, knee replacement, etc. Lumbar spinal osteotomy can correct the deformity of the lumbar spine. For hip and knee joint ankylosis, hip and knee joint pain and activity limitation, accompanied by structural damage on imaging, hip arthroplasty or knee arthroplasty is feasible.
(1) Order of surgery: The order of spine and joint surgery, in principle, should be selected to operate on the site with the most severe deformity and the greatest impact on the patient’s function, taking into account the intraoperative body position. For hip and knee joint replacement, in principle, hip replacement should be performed first, and the center of rotation of the hip joint should be determined first. For patients with bilateral hip and knee ankylosis, bilateral total hip replacement should be performed first, followed by bilateral total knee replacement; or ipsilateral hip and knee replacement can be performed in one phase, and contralateral hip and knee replacement in the second phase to facilitate postoperative functional exercise.
(2) Spinal osteotomy: commonly used spinal osteotomies include Smith-Peterson attachment wedge osteotomy, multisegmental arch wedge osteotomy, and transvertebral foramen wedge osteotomy. Due to the ankylosis of the spine and the narrowing of the internal diameter of the spinal canal, the stress concentration at the osteotomy and the small space for spinal cord avoidance should be avoided during orthopedic surgery to avoid injury to the spinal cord, nerve roots, large blood vessels and spinal instability slippage. The spinal cord, blood pressure, respiration, pulse, and sensory and motor functions of the lower extremities should be closely observed in the surgical field during the course of deformity correction.
(3) Hip arthroplasty: Those who receive total hip arthroplasty early after hip ankylosis have better outcomes than those who delay surgery. Age should not be a restriction for total hip arthroplasty in patients with AS hip flexion ankylosis, and early surgery should be encouraged for patients with high flexion ankylosis. Early surgery can improve the function of the joint and enhance the quality of life of patients. Long-term complications of early total hip arthroplasty, such as loosening of the prosthesis, can be gradually reduced with the improvement of prosthesis design and technology.
(4) Knee arthroplasty: Patients with AS often have osteoporosis and should be alerted to fractures during prosthesis placement. For patients with severe flexion deformity over 60, intraoperative attention should be paid to the coarctation vessels and common peroneal nerve strain injury.
5. Postoperative management
(1) Functional rehabilitation: The focus of rehabilitation is to improve muscle strength, improve joint movement, control pain, and improve motor-sensory coordination. Early and active active training is advocated.
(2) Analgesia and prevention of DVT: refer to the relevant guidelines formulated by the Chinese Medical Association Orthopaedic Branch.
(3) Postoperative medication: Surgery is not an etiological treatment, and AS medication should be resumed as soon as possible after surgery with the assistance of an internist.