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Clinical History

A 34-year-old female presented with on and off lower back pain for four years, associated with occasional right-sided sciatica symptoms. It was aggravated after childbirth. There was no associated weakness, numbness of the extremities or sphincter dysfunction. The physical examination was unremarkable. The patient had a surgical history of caesarian sections and laparoscopic cholecystectomy.

Imaging Findings

Magnetic resonance imaging of the lumbar spine revealed a multilevel diffuse disc bulge, more pronounced at the level of L5-S1 causing bilateral foraminal narrowing and abutment of L5 nerves (Figure 1).

There was a hypoplastic appearance of the right facet joint of L5-S1 level with hypertrophy and mild sclerosis of the contralateral facet joint. There was no surrounding muscle and fat plane disruption to suggest any infection and old or recent spine surgery (Figure 2 and 3).

Discussion

Background

The facet joint, also called the zygapophyseal or apophyseal joint, is a synovial joint formed between the superior articular process of a vertebra and the inferior articular process of the other vertebra immediately above. Anatomically, they are situated between the pedicle and the lamina of the same vertebra. The posterior ligamentous complex strengthens the vertebral columns and stabilizes the facet joints of the adjacent vertebrae.

The bilateral facet joints, along with intervertebral discs, are responsible for transferring weight and direct and limit motions in the spine due to their biomechanical function(1).

Clinical Perspective

Facet joint syndrome is an entity in which structural or mechanical abnormalities of the facet joints can cause back pain. It is the common cause of lower back pain with the prevalence of 15-41%(2).

The factors that contribute to the degeneration of the facet joint are multiple, including osteoarthritis, secondary to inflammation or trauma or subluxation (2).

The unilateral hypoplastic facet joint is a rare condition that leads to facet joint syndrome. The exact aetiology of this anomaly is still unclear but is thought to be the result of a failure of ossification and impaired ossification due to insufficient blood supply in fetal life (3).

Imaging Perspective

The congenital hypoplastic facet joint and pedicle can be seen on conventional radiographs as an absent pedicle with associated abnormal enlargement of the neural foramen. Multidetector Computer Tomography and Magnetic Resonance Imaging demonstrates additional findings such as small anteriorly displaced transverse process, hypoplastic pedicle and facet joint, tilt of the spinous process and contralateral facet joint or pedicle hypertrophy and sclerosis (4). However, not all the cases will show the additional features and will present as isolated finding of unilateral hypoplastic facet joint and pedicle.

Outcome

Numerous anatomic variations and congenital anomalies in the neural arch and its process can affect the ossification process. Most of the patients are asymptomatic and these findings are incidentally noted on imaging for another cause. Some of the variations and anomalies can cause symptoms and the diagnosis is made on the imaging to rule out fracture, dislocation or degenerative changes.

Unilateral hypoplastic facet joint is a rare cause of the chronic back pain. If this is an isolated finding, conservative therapy is usually recommended. However, if there is associated disc herniation or canal stenosis, orthopedic surgery should be sought if the condition is debilitating.

Take-Home Message / Teaching Points

Unilateral hypoplastic facet joint is uncommon but should be considered as possibility if the patient has chronic back pain.

Written informed patient consent for publication has been obtained.

Differential Diagnosis List

Unilateral hypoplastic facet joint

Hypoplastic facet joint

Osteoarthritis

Osteomyelitis with resorption of the bone

Spine surgery

Final Diagnosis

Unilateral hypoplastic facet joint

Liscense

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Figures

Magnetic resonance imaging of lumbosacral spine without IV contrast, sagittal view of T1 WI (a), T2 WI(b) and STIR(c), demons

Magnetic resonance imaging of lumbosacral spine without Iv contrast, axial section T1WI (a, b) and T2WI (c, d). The images sh

. Magnetic resonance imaging of Lumbosacral spine without IV contrast, sagittal view T1WI (a) and T2WI(b) of the left side sh

Medical Analysis Report

Radiological Findings

Based on the provided lumbar spine MRI (sagittal and axial sequences), the following features are observed:
1. At the L4/5 segment, the right-sided facet joint (pedicle and facet) is noticeably smaller than the contralateral side, presenting as hypoplasia (i.e., underdeveloped or “low-grade growth”).
2. The intervertebral disc signal at this segment appears relatively normal, with no significant disc herniation or notable spinal canal stenosis.
3. The adjacent vertebral body signals are generally normal, with no clear evidence of fracture, dislocation, or bony destruction.
4. Other lumbar facet joints show no significant abnormalities, and the conus medullaris and dural sac region appear essentially normal in signal.

Potential Diagnoses

Congenital Unilateral Hypoplastic Facet Joint
Explanation: The lumbar MRI findings indicate unilateral (most likely right-sided) underdevelopment of the facet and pedicle, suggesting a congenital structural anomaly; this may lead to compensatory changes in the contralateral facet or other structures and can cause chronic low back pain or sciatica.
Degenerative Facet Joint Syndrome
Explanation: A common cause of chronic low back pain. If a congenital facet abnormality is compounded by altered weight-bearing or mild degeneration over time, it may trigger facet joint inflammation or mild osteophytic changes. However, current imaging shows only minor structural abnormalities with no marked hypertrophic changes.
Mild Lumbar Disc Degeneration or Early Herniation
Explanation: This is a common differential diagnosis for chronic low back pain and sciatica. While current imaging does not clearly indicate a significant disc protrusion, correlating with clinical symptoms is important.

Final Diagnosis

Considering the patient’s age (34-year-old female), postpartum exacerbation of back pain, and a history of intermittent right-sided sciatica, together with the MRI findings, the most likely diagnosis is:
“Chronic low back pain due to congenital unilateral (right-sided) facet hypoplasia (with mild right-sided sciatic nerve root irritation).”
Currently, there is no strong evidence of a significant disc herniation. If it is necessary to rule out other pathologies, additional imaging or electrophysiological studies may be considered.

Treatment Plan and Rehabilitation

Considering the patient’s relatively mild symptoms and lack of significant neurological deficits, conservative management is recommended initially. If symptoms are not well controlled, surgical indications may be further evaluated. Main strategies include:

Conservative Treatment
- Oral or topical nonsteroidal anti-inflammatory drugs (NSAIDs) to alleviate pain and inflammation.
- Acupuncture and physiotherapy (e.g., heat therapy, electrical stimulation, ultrasound) to relieve local facet discomfort.
- If pain is severe, consider local facet joint block injections for short-term pain relief.
Rehabilitation Exercises and Exercise Prescription

Should be performed progressively, following the FITT-VP principles (frequency, intensity, time, type, progression, and individualization), and adjusted based on the patient’s specific condition.
- Early-Phase Exercises (Acute or Painful Phase)
  - Frequency: Light activities 2-3 times a day, each session lasting 5-10 minutes.
  - Intensity: Low-intensity stretching and core stabilization (such as abdominal bracing, pelvic tilts).
  - Time: Increase duration gradually according to tolerance, aiming to reach 15-20 minutes per session.
  - Type: Emphasize protective movements, such as supine core stabilization with knees bent. Avoid excessive loading or vigorous twisting of the waist.
- Progressive Exercises (Recovery or Chronic Phase)
  - Frequency: 3-5 times per week, 20-30 minutes each session.
  - Intensity: Gradually increase core training intensity (e.g., planks, seated rowing with a low load).
  - Type: Introduce low-impact strength training and stretching for the lumbar region, focusing on coordination and flexibility.
  - Progression: As core and back strength improve, gradually extend exercise sessions beyond 30 minutes and consider Pilates or yoga to enhance core stability.
- Individualization and Safety
  - In cases of low bone density or concerns related to postpartum status or surgical history, increase precautions and strictly control exercise intensity and range of motion.
  - Apply ice or heat therapy after each session as needed. If significant pain or worsening neurological symptoms occur, stop and seek medical evaluation.
Surgical or Minimally Invasive Intervention

For patients with severe disc herniation, spinal canal stenosis, or significant nerve root compression not responding to conservative treatment, referral to orthopedics or spine surgery for decompression and stabilization may be necessary. If the issue is merely a congenital variation with mild symptoms, surgery is not indicated.

Disclaimer:
This report is based on the current clinical and imaging information and is for reference only. It does not replace an in-person consultation or the diagnostic and treatment advice of a professional physician. If any symptoms change or if there are further concerns, please seek immediate medical attention.

Human Doctor Final Diagnosis

Unilateral hypoplastic facet joint

AI Doctor