PROM Injury: Understanding, Causes, Symptoms, and Prevention

What is a PROM injury?

A PROM injury refers to damage sustained when a joint or tissue is moved through its Passive Range Of Motion (PROM) in a manner that exceeds its physiological limits or is performed inappropriately, leading to a strain, sprain, or other tissue damage.

Understanding Range of Motion (ROM)

To comprehend a PROM injury, it's crucial to first understand the concept of Range of Motion (ROM). ROM describes the full movement potential of a joint, from full extension to full flexion, abduction, adduction, rotation, etc. There are three primary types of ROM:

• Active Range of Motion (AROM): The range a person can move a joint independently, using their own muscles.
• Active-Assistive Range of Motion (AAROM): The range a person can move a joint with some assistance from an external force (e.g., a therapist, a device, or the other limb).
• Passive Range of Motion (PROM): The range a joint can be moved by an external force (e.g., a therapist, a machine, or gravity) without any muscle contraction from the individual. During PROM, the individual's muscles are relaxed, allowing the external force to determine the movement. PROM is often used for assessment, to maintain joint mobility in paralyzed or unconscious individuals, or as a therapeutic intervention.

Defining a PROM Injury

A "PROM injury" is not a distinct diagnostic term like "ACL tear" or "rotator cuff tendinopathy." Instead, it describes an injury that occurs as a direct result of a passive movement being applied to a joint or limb. These injuries typically happen when:

• Excessive Force is Applied: The external force moving the joint is too great, pushing the joint beyond its normal anatomical limits.
• Improper Technique is Used: The movement is performed incorrectly, putting undue stress on specific tissues (e.g., applying a rotational force when only flexion/extension is appropriate).
• Pre-existing Conditions are Ignored: The individual has an underlying vulnerability (e.g., joint instability, hypermobility, or a pre-existing injury) that makes them susceptible to harm during PROM.
• Lack of Communication: The person receiving PROM cannot communicate pain or discomfort effectively, or their feedback is ignored.

Essentially, a PROM injury signifies that the passive movement, intended to be therapeutic or diagnostic, inadvertently caused tissue damage.

Common Mechanisms and Scenarios

PROM injuries can occur in various settings, often due to a combination of factors:

• Therapist/Trainer Error:
  • Overstretching: Pushing a joint beyond its physiological end-range, leading to ligamentous sprains or muscle strains.
  • Poor Body Mechanics: The person performing the PROM uses incorrect leverage or positioning, leading to uncontrolled or excessive forces.
  • Ignoring End-Feels: Failing to recognize the natural 'end-feel' of a joint (e.g., soft tissue approximation, bone-on-bone, capsular) and forcing past a pathological end-feel (e.g., empty end-feel indicating instability).
• Patient Factors:
  • Muscle Guarding/Spasm: Involuntary muscle contraction by the patient in response to pain or fear, which, if forced against, can lead to muscle tears.
  • Hypermobility: Individuals with naturally lax ligaments may be more prone to joint instability if not handled with care.
  • Hypomobility/Stiffness: While PROM aims to improve stiffness, aggressive stretching of stiff joints can cause micro-tears in joint capsules or surrounding tissues.
  • Pain Tolerance: A patient's inability to tolerate the stretch, leading to protective responses that can be overcome by excessive force.
• Specific Tissues at Risk:
  • Ligaments: Sprains (stretching or tearing of ligaments) if the joint is forced into an unstable position.
  • Muscles: Strains (stretching or tearing of muscle fibers) if the muscle is overstretched, especially if it's not relaxed.
  • Joint Capsule: Damage or inflammation to the fibrous sac enclosing the joint.
  • Nerves: Compression or stretching of nerves if the movement impinges on a nerve pathway.
  • Cartilage/Meniscus: Less common, but forceful, uncontrolled movements can potentially exacerbate existing cartilage damage or cause new issues.

Signs and Symptoms of a PROM-Related Injury

The symptoms of a PROM injury are similar to other musculoskeletal injuries and depend on the specific tissue damaged:

• Immediate Pain: Often sharp, sudden pain at the time of the incident, distinct from the expected stretch sensation.
• Increased Pain with Movement: Pain that worsens when the affected joint is moved, especially in the direction that caused the injury.
• Swelling: Localized inflammation around the joint, developing within hours.
• Bruising/Discoloration: May appear hours to days after the injury, indicating bleeding under the skin.
• Loss of Function or Range of Motion: Paradoxically, a PROM injury can lead to a reduction in the very range of motion it was intended to improve, due to pain, swelling, or muscle guarding.
• Instability: A feeling of the joint "giving way" or being loose, particularly if ligaments are damaged.
• Audible Pop or Tear: Some individuals may hear or feel a distinct sound or sensation at the moment of injury.

Preventing PROM Injuries

Prevention is paramount when performing or receiving PROM:

• Thorough Assessment: Always conduct a comprehensive assessment of the individual's current ROM, pain levels, medical history, and any contraindications (e.g., recent fractures, acute inflammation, unhealed surgical sites).
• Clear Communication: Maintain continuous verbal feedback with the individual. They should report any discomfort beyond a "good stretch." Never push through sharp pain.
• Gradual Progression: Start with small, controlled movements and slowly increase the range as tolerated. Avoid ballistic or jerky movements.
• Knowledge of Anatomy and Biomechanics: The practitioner must have a deep understanding of joint anatomy, normal physiological end-feels, and the specific limitations of each joint.
• Proper Stabilization: Stabilize the proximal joint segment to ensure the movement is isolated to the target joint and unwanted compensatory movements are prevented.
• Respect Pain Thresholds: Pain is a protective mechanism. It should be respected, not overridden.
• Educate the Patient: Inform the individual about what to expect and encourage them to communicate any unusual sensations.

Management and Recovery

If a PROM injury is suspected, immediate action is crucial:

• Stop the Activity: Discontinue the PROM immediately.
• Initial R.I.C.E. Protocol: Apply Rest, Ice, Compression, and Elevation to the affected area to manage pain and swelling.
• Professional Medical Assessment: Seek evaluation from a qualified healthcare professional (e.g., physician, physical therapist). They can accurately diagnose the extent and nature of the injury.
• Diagnostic Imaging: Depending on the severity, X-rays, MRI, or ultrasound may be used to identify specific tissue damage.
• Rehabilitation: A tailored rehabilitation program will be prescribed, focusing on:
  • Pain Management: Modalities, medication.
  • Protection and Rest: Allowing injured tissues to heal.
  • Progressive Exercise: Gradually restoring ROM, strength, and function, often starting with gentle active movements before reintroducing controlled passive stretches.
  • Proprioceptive Training: Re-educating the joint's sense of position and movement.

Conclusion

While Passive Range of Motion is a valuable tool in rehabilitation and fitness to maintain or improve joint mobility, it is not without risk. A PROM injury occurs when this technique is performed improperly or with excessive force, leading to damage to ligaments, muscles, joint capsules, or other tissues. Understanding the mechanisms of these injuries, recognizing their symptoms, and adhering to strict preventative measures are essential for anyone performing or receiving PROM to ensure its benefits are realized safely and effectively. Always prioritize patient comfort, clear communication, and a thorough understanding of human anatomy and biomechanics.