The ICD-10-CM definition of initial visit is little complicated than the usual understanding of the word. Specifically, guidelines state that a seventh character A is “used for the initial encounter for the injury or condition while the patient is receiving ACTIVE TREATMENT for the injury. Examples of active treatment are: surgical treatment, emergency department encounter, and evaluation and treatment. so, as described earlier, you will be coding ICD S43.431A to support surgery procedure code instead of M24.111 in described situation.
For example: The patient is evaluated for injury that cannot be managed at this time. The physician applies immobilization and ice and instructs the patient to follow up with orthopedics. This would be reported using Initial Encounter for injury.
When the orthopedist rechecks and treat the patient, the patient is receiving initial active treatment for this injury. This is the first encounter at which the patient receives definitive care (initial treatment was comfort care only). Per ICD-10 guidelines, you would again report for an initial encounter.
To clarify, let's take another example: The patient has a greenstick fracture, which is definitively managed with a cast or splint. You would report this with greenstick fracture, initial encounter for closed fracture. Later, the same orthopedist who provided care in the beginning, rechecks the injury in the office. This is a subsequent encounter because the provider cared for the same condition, previously.
Subsequent Encounter is little simple, as encounters after the patient has received active treatment of the injury and is receiving routine care for the injury during the healing or recovery phase.
For examples: cast change or removal, removal of external or internal fixation device, medication adjustment, other aftercare and follow up visits following injury treatment.
Whereas, Sequela Encounter is for use for complications that arise as a direct result of an injury, such as scar formation after a burn. The scars are sequelae of the burn, as the the late effects of an injury.
Perhaps the most common sequela is pain. Many patients receive treatment long after an injury has healed as a result of pain. These kinds of visits may be reported as G89.21 chronic pain due to trauma and sequela encounter code of the injury.
Hope this clears your doubts!