Concomitant osteoarthritis of hip/knee joint and lumbar spinal degeneration is commonly seen in elderly population. These degeneration changes of spine would change sagittal or coronal alignment and spinal flexibility in varies degrees. Total hip and knee arthroplasty (THA/TKA) are among the most successful orthopedic operations performed, aiming at the alleviation of osteoarthritic pain. Normal alignment of the spine and pelvis in the sagittal plane is critical to maintain an upright standing position with minimal energy consumption. However, there is a scarcity of studies on how THA or TKA influences the parameters of the spine and the pelvis.

Compared with the balance of coronal plane, more attention is paid to the balance of sagittal plane. The objectives of this study are to investigate changes in the truncal parameters after THA or TKA and assess whether these parameters are improved or deteriorated after these operations.

Inclusion Criteria:

1. Primary degenerative arthritis of the knee or hip
2. Those who have undergone artificial knee or hip replacement surgery
3. Follow up surgery for at least 1 year
4. Track the whole trunk lower limb sagittal plane coronal aligament before and after surgery

Exclusion Criteria:

1. Previous hip surgery
2. Previous spine surgery
3. Contracture after hip fusion surgery
4. Scoliosis over 10 degrees combined with neuropathy
5. Patients with flexion contracture after knee joint surgery
6. Rheumatoid arthritis lesions

Concomitant osteoarthritis of hip/knee joint and lumbar spinal degeneration patients who take Total hip and knee arthroplasty