Tennis Elbow (Lateral Epicondylitis): This condition is characterized by pain on the lateral aspect of the elbow, which can radiate to the posterior wrist, especially with activities involving wrist extension. The pain is exacerbated by resisted wrist extension, making it a prime candidate for the symptoms described.

Wrist Extensor Tendinopathy: Similar to tennis elbow, this condition affects the tendons on the back of the wrist, leading to pain during wrist extension. It's a common issue in individuals who frequently use their wrists in extension, such as in sports or certain occupations.
De Quervain's Tenosynovitis: This condition affects the tendons on the thumb side of the wrist, leading to pain and tenderness, especially with movements involving the thumb and wrist extension. While it primarily affects the lateral wrist, it can cause referred pain to the posterior aspect.
Scapholunate Ligament Injury: An injury to this ligament, which is crucial for wrist stability, can cause pain on the lateral and posterior aspects of the wrist, especially with movements that stress the ligament, such as wrist extension.

Ganglion Cyst: Although often benign, a ganglion cyst can cause significant pain and discomfort, especially if it compresses nearby nerves. It's essential to identify and potentially remove the cyst to alleviate symptoms.
Radial Nerve Compression: Compression of the radial nerve can cause pain, weakness, and numbness in the wrist and hand, particularly with activities involving wrist extension. Early diagnosis is crucial to prevent long-term nerve damage.
Infectious or Inflammatory Arthritis: Conditions like septic arthritis or rheumatoid arthritis can cause severe wrist pain, swelling, and stiffness. These conditions require prompt medical attention to prevent joint destruction and systemic complications.

Kienbock's Disease: A rare condition characterized by the collapse of the lunate bone in the wrist, leading to pain and limited wrist motion. It's more common in young adults and can be a cause of chronic wrist pain.
Pisotriquetral Joint Disorders: Disorders of this small joint in the wrist can cause lateral and posterior wrist pain, especially with certain movements. It's a less common cause of wrist pain but should be considered in the differential diagnosis.