Mechanical Low Back Pain: This is the most common cause of back pain and can radiate to the hip due to the proximity of the lumbar spine to the hip joint. It is often related to muscle strain, poor posture, or overuse.

Osteoarthritis of the Hip: A common condition that can cause both hip and back pain due to the referred pain pattern from the hip joint to the lower back.
Degenerative Disc Disease: A condition where the spinal discs lose their cushioning ability, leading to pain in the back and potentially radiating to the hip.
Piriformis Syndrome: A condition where the piriformis muscle irritates the sciatic nerve, causing pain in the back and hip.
Sacroiliitis: Inflammation of the sacroiliac joints, which can cause pain in the lower back and hips.

Cauda Equina Syndrome: A serious condition where the nerves in the spinal canal are compressed, leading to severe back and hip pain, as well as potential neurological deficits. It requires immediate medical attention.
Spinal Infection (e.g., Osteomyelitis, Discitis): Infections of the spine that can cause severe back pain and potentially radiate to the hip, requiring prompt diagnosis and treatment.
Fractures: Especially in individuals with osteoporosis or those who have experienced trauma, fractures can cause sudden onset of back and hip pain.
Metastatic Cancer: Cancer that has spread to the bones of the spine or hip can cause significant pain and requires early detection for effective management.

Ankylosing Spondylitis: A form of arthritis that primarily affects the spine, although it can also affect other joints, leading to back and hip pain.
Paget's Disease of Bone: A condition that affects bone remodeling, leading to enlarged and misshapen bones, which can cause pain in the back and hips.
Osteonecrosis of the Femoral Head: A condition where the blood supply to the head of the femur is interrupted, leading to bone death and potentially severe hip pain that can radiate to the back.