Osteoarthritis (OA): The patient's age, history of arthritis, and symptoms of joint pain that are worst in the morning and improve with activity are classic for OA. The absence of swelling, redness, and deformity also supports this diagnosis, as OA tends to cause more pain than inflammation.

Meniscal Tear: Given the patient's age and history of arthritis, a meniscal tear is possible, especially if the pain is localized to a specific area of the knee. However, the lack of swelling and the fact that the pain improves with walking make this less likely.
Ligamentous Sprain: Although less common in this age group without a history of trauma, a ligamentous sprain could cause knee pain. The absence of swelling and the improvement of pain with activity make this diagnosis less likely.
Bursitis: Prepatellar or infrapatellar bursitis could cause knee pain, but the absence of swelling and redness makes this less likely.

Septic Arthritis: Although the patient does not have fever, swelling, or redness, septic arthritis is a medical emergency that can occur without these classic signs, especially in the elderly. A high index of suspicion is necessary, and joint aspiration may be required to rule out this diagnosis.
Deep Vein Thrombosis (DVT): The patient's history of hyperlipidemia and hypertension increases her risk for DVT. While the pain profile does not strongly suggest DVT, the presence of a palpable popliteal pulse does not rule it out, and further evaluation may be necessary if other risk factors or symptoms are present.
Osteonecrosis: This condition can cause knee pain and is more common in older adults, especially those with a history of steroid use or certain medical conditions. However, it would typically cause more constant pain and might be associated with localized tenderness.

Rheumatoid Arthritis (RA): Although RA can cause knee pain, it typically presents with symmetric joint involvement, morning stiffness lasting more than an hour, and systemic symptoms like fever and fatigue, which are not mentioned in this case.
Gout or Pseudogout: These conditions can cause acute knee pain and are more common in older adults. However, they typically present with sudden onset of intense pain, swelling, and redness, which are not present in this patient.
Neuropathic Pain: Rarely, neuropathic pain from a lumbar radiculopathy or neuropathy could refer pain to the knee. However, this would typically be associated with other neurological symptoms like numbness, tingling, or weakness, which are not mentioned.