Degenerative Disorders Practice Questions

Q: What is the deformity most commonly seen in primary osteoarthritis of the knee joint?

Genu varus. ### Explanation **Correct Answer: C. Genu varus** In primary osteoarthritis (OA) of the knee, the **medial compartment** is the most common site of cartilage degeneration. This occurs because the mechanical axis of the lower limb normally passes slightly medial to the center of the knee joint, causing the medial compartment to bear approximately 60-70% of the load during walking. As the medial articular cartilage thins and the joint space narrows, the tibia tilts medially relative to the femur, resulting in a **bow-legged** appearance known as **Genu varus**. **Analysis of Incorrect Options:** * **A. Genu valgum (Knock-knees):** This is less common in primary OA. It occurs when the lateral compartment undergoes preferential degeneration. It is more frequently associated with Rheumatoid Arthritis or secondary OA. * **B. Genu recurvatum:** This refers to hyperextension of the knee. It is typically caused by ligamentous laxity (e.g., polio, Ehlers-Danlos syndrome) or quadriceps weakness, rather than primary degenerative changes. * **D. Procurvatum:** This is a forward bowing of the bone (fixed flexion deformity). While OA can lead to a fixed flexion deformity due to posterior capsular contracture, "Genu varus" is the classic coronal plane deformity described. **Clinical Pearls for NEET-PG:** * **Kellgren-Lawrence Grading:** The standard radiological classification for OA (Grade 0-4), based on joint space narrowing, osteophytes, and sclerosis. * **First Sign on X-ray:** Often subchondral sclerosis or small osteophytes; however, joint space narrowing is the hallmark. * **Management:** High Tibial Osteotomy (HTO) is a high-yield surgical option for young, active patients with isolated medial compartment OA and varus deformity to realign the weight-bearing axis. * **Heberden’s Nodes:** Found at the DIP joints (characteristic of primary OA).

Q: A 74-year-old woman presents with a months-long history of pain in her right hand and lower back, which is worsening and interfering with her daily activities. The pain increases as the day progresses. She denies any history of trauma and is otherwise healthy. Over-the-counter acetaminophen usually provides relief. On examination, there is soft tissue swelling and tenderness of her second and third distal interphalangeal joints in the right hand, and she experiences pain in her lower back upon forward flexion. There is no erythema or joint effusion in any other joints. What is the most likely explanation for the joint pain in osteoarthritis?

Osteophytes can cause pain.. **Explanation:** The clinical presentation of a 74-year-old with activity-related pain, involvement of the distal interphalangeal (DIP) joints (Heberden’s nodes), and lower back pain without systemic symptoms is classic for **Osteoarthritis (OA)**. **Why Option D is Correct:** In OA, the articular cartilage is aneural (lacks nerves). Therefore, the pain does not originate from the cartilage itself but from secondary structural changes. **Osteophytes** (bony outgrowths) are a hallmark of OA; they cause pain by stretching the periosteum (which is richly innervated) and by causing mechanical impingement on surrounding soft tissues and nerves. **Analysis of Incorrect Options:** * **Option A:** While OA is primarily degenerative, **secondary synovitis** (synovial inflammation) often occurs due to the release of cartilage breakdown products into the joint space, contributing significantly to the pain. * **Option B:** While ligaments can be strained due to joint instability, "ligament inflammation" is not the primary or most common driver of pain in OA compared to subchondral and periosteal changes. * **Option C:** While **microfractures** of the subchondral bone (due to loss of shock-absorbing cartilage) are a known source of pain, "clinically visible fractures" (macro-fractures) are not a standard feature of OA. **NEET-PG High-Yield Pearls:** * **Nodal Involvement:** DIP joints (Heberden’s nodes) and PIP joints (Bouchard’s nodes) are characteristic. The MCP joints are typically spared (unlike Rheumatoid Arthritis). * **Pain Pattern:** Mechanical pain (worsens with use, improves with rest). * **Radiological Hallmarks (LOSS):** **L**oss of joint space, **O**steophytes, **S**ubchondral sclerosis, and **S**ubchondral cysts. * **First-line Management:** Weight loss, physical therapy, and Acetaminophen (as seen in this patient).

Q: Which compartment of the knee is most commonly involved in osteoarthritis?

Medial compartment. **Explanation:** **1. Why the Medial Compartment is Correct:** The knee joint consists of three compartments: medial tibiofemoral, lateral tibiofemoral, and patellofemoral. In the normal standing position (neutral alignment), the mechanical axis of the lower limb passes slightly medial to the center of the knee joint. Consequently, approximately **60–70% of the weight-bearing load** is transmitted through the **medial compartment**. This chronic mechanical stress leads to accelerated wear and tear of the articular cartilage, making it the most common site for primary osteoarthritis. **2. Analysis of Incorrect Options:** * **Lateral Compartment:** This compartment bears significantly less load than the medial side. Isolated lateral compartment OA is less common and is often associated with a valgus (knock-knee) deformity. * **Medial and Lateral Compartments:** While "tricompartmental" OA occurs in advanced stages, the disease typically **starts** in a single compartment. The medial compartment is almost always the initial site of involvement. * **Patellofemoral Compartment:** While frequently involved (especially in activities like climbing stairs), it is rarely the *most* common or isolated site compared to the medial tibiofemoral joint in primary OA. **3. Clinical Pearls for NEET-PG:** * **Deformity:** Medial compartment OA leads to loss of joint space medially, resulting in **Genu Varum** (Bow-leg deformity). * **Radiological Hallmarks:** Look for the "LOSS" mnemonic: **L**oss of joint space, **O**steophytes, **S**ubchondral sclerosis, and **S**ubchondral cysts. * **Kellgren-Lawrence Grading:** This is the standard radiological classification used to assess the severity of Knee OA. * **Management:** High Tibial Osteotomy (HTO) is a surgical option specifically designed to shift weight from the diseased medial compartment to the healthy lateral compartment in young, active patients.

Question 1

Osteoarthritis is typically not seen in which of the following joints?

Accepted Answer

Ankle joints

Answer

Knee joints

Answer

Hip joints

Answer

First metacarpophalangeal joint

Question 2

In patients with osteoarthritis of the knee joint, atrophy occurs most commonly in which muscle?

Accepted Answer

Quadriceps only

Answer

Hamstrings only

Answer

Both quadriceps and hamstrings

Answer

Gastrocnemius

Question 3

What is the deformity most commonly seen in primary osteoarthritis of the knee joint?

Accepted Answer

Genu varus

Answer

Genu valgum

Answer

Genu recurvatum

Answer

Procurvatum

Question 4

A 74-year-old woman presents with a months-long history of pain in her right hand and lower back, which is worsening and interfering with her daily activities. The pain increases as the day progresses. She denies any history of trauma and is otherwise healthy. Over-the-counter acetaminophen usually provides relief. On examination, there is soft tissue swelling and tenderness of her second and third distal interphalangeal joints in the right hand, and she experiences pain in her lower back upon forward flexion. There is no erythema or joint effusion in any other joints. What is the most likely explanation for the joint pain in osteoarthritis?

Accepted Answer

Osteophytes can cause pain.

Answer

Synovial inflammation is not the cause of pain.

Answer

Ligament inflammation is a common cause of pain.

Answer

Clinically visible fractures are a common cause of pain.

Question 5

Which compartment of the knee is most commonly involved in osteoarthritis?

Accepted Answer

Medial compartment

Answer

Lateral compartment

Answer

Medial and lateral compartments

Answer

Patellofemoral compartment

Degenerative Disorders — MCQs

Degenerative Disorders — MCQs

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