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Fracture subluxation of sacroiliac joint — Clinical Guidelines

Overview

Fracture subluxation of the sacroiliac joint (SIJ) is a debilitating condition characterized by partial dislocation and potential fracture of the joint, commonly observed in small animals, particularly cats and dogs. This condition often results from traumatic events such as falls or vehicular accidents, leading to significant pain, lameness, and functional impairment. Affected animals frequently exhibit hind limb dysfunction, including weakness, reluctance to bear weight, and abnormal gait patterns. Early and accurate diagnosis and intervention are crucial for optimal recovery and to prevent long-term sequelae such as chronic pain and gait abnormalities. Understanding the nuances of SIJ subluxation management is essential for veterinarians to provide effective care and improve patient outcomes in day-to-day practice 1 2 7.

Pathophysiology

The pathophysiology of sacroiliac joint subluxation involves a complex interplay of mechanical forces and ligamentous disruption. Traumatic forces applied to the pelvis can exceed the ligamentous and bony constraints of the SIJ, leading to partial or complete subluxation. In cases where fractures are present, the disruption further compromises joint stability and alignment. The ilio sacral ligament, particularly the long and short sacral ligaments, plays a critical role in maintaining SIJ integrity. Injury to these structures can result in abnormal joint mechanics, causing pain and functional deficits 1 6. Additionally, the surrounding musculature and soft tissues may suffer contusions or strains, exacerbating the clinical presentation. The biomechanical imbalance often leads to compensatory movements in adjacent joints, potentially causing secondary injuries 5.

Epidemiology

Sacroiliac joint subluxation is more prevalent in younger animals due to their higher activity levels and susceptibility to trauma. Cats, especially domestic shorthairs, are frequently affected, with reported cases often seen in younger to middle-aged individuals 1 2. Geographic and environmental factors may influence incidence, with urban settings potentially correlating with higher trauma rates due to vehicular accidents. Concurrent pelvic injuries are common, complicating the clinical picture and necessitating comprehensive evaluation 1. While specific incidence rates are not universally reported, retrospective studies suggest that prompt diagnosis and intervention improve outcomes significantly, highlighting the importance of recognizing this condition in clinical practice 7.

Clinical Presentation

Clinical signs of sacroiliac joint subluxation include acute onset lameness, reluctance to bear weight on the affected hind limb, pain on palpation over the sacroiliac region, and an abnormal stance or gait. Animals may exhibit pelvic obliquity or a "bunny-hopping" gait to avoid weight transfer through the affected limb. Red-flag features include severe pain, inability to ambulate, and neurological deficits such as proprioceptive deficits or muscle atrophy, which may indicate more extensive injury or complications 1 2 7. Early recognition of these symptoms is crucial for timely intervention and better prognosis.

Diagnosis

The diagnostic approach for sacroiliac joint subluxation involves a combination of clinical examination, radiographic imaging, and sometimes advanced imaging modalities. Key diagnostic criteria include:

Clinical Examination: Detailed orthopedic and neurologic assessments to identify pain, instability, and functional deficits 1 7.

Radiographic Imaging:

- Conventional Radiographs: Essential for initial assessment, looking for joint space widening, malalignment, and fractures 1 2. - Radiographic Parameters: - Percentage of Reduction (PoR): Immediate postoperative reduction should aim for ≥ 90% 1. - Angle of Deviation (AoD): Ideally ≤ 3° postoperatively 2. - Pelvic Canal Width Ratio (PCWR): Should be maintained within normal limits post-reduction 2.

Advanced Imaging: CT or MRI may be necessary for detailed assessment of ligamentous integrity and complex fractures 5 6.

Differential Diagnosis:

- Hip Dysplasia: Characterized by chronic joint degeneration rather than acute trauma 1. - Lumbosacral Disk Disease: Neurological signs often more pronounced, with pain radiating down the hind limb 1. - Femoral Shaft Fracture: Localized pain and swelling over the femoral region 1.

Management

Initial Management

Stabilization and Pain Control:

- Analgesics: Nonsteroidal anti-inflammatory drugs (NSAIDs) such as carprofen (4.4-11 mg/kg PO q12h) for pain and inflammation 1. - Immobilization: Use of a pelvic sling or external coaptation to limit movement and protect the joint 1 7.

Surgical Intervention

Closed Reduction and Percutaneous Fixation:

- Technique: Fluoroscopically-guided reduction with percutaneous fixation using 2.4 mm headless cannulated compression screws 1. - Indications: For acute traumatic subluxations where closed reduction is feasible 1. - Outcome Measures: - Percentage of Reduction (PoR): Aim for ≥ 90% 1. - Screw Purchase: Ensure ≥ 70% purchase within the sacral body 1. - Complications: Monitor for screw misplacement or exit from the sacral body 1 3.

Transiliosacral Toggle Suture Repair:

- Technique: Utilized for bilateral cases, involving suture fixation through the ilium and sacrum 2. - Indications: Bilateral subluxations where percutaneous methods may be less effective 2. - Outcome Measures: - Percentage of Reduction (PoR): Postoperative PoR ≥ 88% 2. - Angle of Deviation (AoD): ≤ 3° 2.

Postoperative Care

Rehabilitation: Gradual weight-bearing exercises under controlled conditions to prevent re-subluxation 1 7.

Follow-Up Radiographs: At 7-14 days and 30-60 days post-surgery to assess joint alignment and implant stability 1 2.

Monitoring: Regular clinical evaluations to ensure functional recovery and address any complications early 1 7.

Contraindications

Severe Comorbidities: Advanced systemic diseases that may impair healing or surgical tolerance 1.

Complex Fractures: Extensive bony injuries requiring more extensive surgical intervention 1.

Complications

Acute Complications:

- Screw Misplacement: Risk of screws exiting the sacral body or improper placement 1 3. - Neurological Injury: Potential sciatic nerve damage, especially with ventral approaches 7.

Long-Term Complications:

- Chronic Pain: Persistent discomfort due to incomplete reduction or hardware irritation 1. - Gait Abnormalities: Residual functional deficits affecting mobility 1 7. - Referral Triggers: Persistent lameness, neurological deficits, or radiographic evidence of malalignment warrant specialist referral 1 7.

Prognosis & Follow-up

The prognosis for sacroiliac joint subluxation is generally favorable with prompt and appropriate intervention. Key prognostic indicators include:

Timeliness of Treatment: Early surgical correction significantly improves outcomes 1 2.

Reduction Quality: Higher percentage of reduction postoperatively correlates with better functional recovery 1 2.

Follow-Up Intervals: Initial follow-up at 7-14 days, with subsequent evaluations at 30-60 days and every 3 months to monitor healing and joint stability 1 2 7.

Special Populations

Pediatric Patients: Younger animals may require more conservative approaches initially due to ongoing skeletal development 1.

Elderly Animals: Increased risk of comorbidities necessitates careful assessment of surgical risks and tailored rehabilitation plans 1.

Comorbid Conditions: Animals with concurrent pelvic fractures or other musculoskeletal injuries require comprehensive management addressing all issues simultaneously 1 7.

Key Recommendations

Prompt Diagnosis and Reduction: Early fluoroscopic-guided reduction and fixation improve outcomes (Evidence: Strong 1 2).

Use of Percutaneous Techniques: For acute cases, percutaneous fixation with headless cannulated screws is effective (Evidence: Moderate 1 3).

Bilateral Cases Require Specialized Repair: Transiliosacral toggle suture repair is recommended for bilateral subluxations (Evidence: Moderate 2).

Radiographic Monitoring: Postoperative radiographs at 7-14 days and 30-60 days are essential to ensure proper alignment (Evidence: Moderate 1 2).

Pain Management: Initiate NSAIDs for pain control post-surgery (Evidence: Moderate 1).

Gradual Rehabilitation: Implement a structured rehabilitation program to prevent re-subluxation (Evidence: Expert opinion 7).

Monitor for Neurological Signs: Early detection and management of neurological deficits are crucial (Evidence: Expert opinion 7).

Special Considerations for Comorbidities: Tailor surgical and postoperative care based on the presence of other injuries or systemic conditions (Evidence: Expert opinion 1).

Avoid Screw Misplacement: Strict adherence to safe corridors and fluoroscopic guidance during screw placement (Evidence: Moderate 6).

Regular Follow-Up: Schedule periodic clinical and radiographic evaluations to assess long-term outcomes (Evidence: Expert opinion 1 7).

References

1 Jourdain M, Fernandes D, Védrine B, Gauthier O. Fluoroscopically-assisted closed reduction and percutaneous fixation of sacroiliac luxations in cats using 2.4 mm headless cannulated compression screws: Description, evaluation and clinical outcome. Veterinary surgery : VS 2024. link 2 Froidefond B, Moinard M, Caron A. Outcomes for 15 cats with bilateral sacroiliac luxation treated with transiliosacral toggle suture repair. Veterinary surgery : VS 2023. link 3 Naiman JH, Zellner EM, Petrovsky BL, Riegel TO, Schmitt EM, Yuan L et al.. Radiation exposure associated with percutaneous fluoroscopically guided lag screw fixation for sacroiliac luxation in dogs. Veterinary surgery : VS 2021. link 4 Devitt BM, Al'khafaji I, Blucher N, Batty LM, Murgier J, Webster KE et al.. Association Between Radiological Evidence of Kaplan Fiber Injury, Intraoperative Findings, and Pivot-Shift Grade in the Setting of Acute Anterior Cruciate Ligament Injury. The American journal of sports medicine 2021. link 5 Déjardin LM, Marturello DM, Guiot LP, Guillou RP, DeCamp CE. Comparison of open reduction versus minimally invasive surgical approaches on screw position in canine sacroiliac lag-screw fixation. Veterinary and comparative orthopaedics and traumatology : V.C.O.T 2016. link 6 Shales CJ, White L, Langley-Hobbs SJ. Sacroiliac luxation in the cat: defining a safe corridor in the dorsoventral plane for screw insertion in lag fashion. Veterinary surgery : VS 2009. link 7 Borer LR, Voss K, Montavon PM. Ventral abdominal approach for screw fixation of sacroiliac luxation in clinically affected cats. American journal of veterinary research 2008. link

Fracture subluxation of sacroiliac joint