Description of Intervention
Extensor tendon injury frequently accompanies complex injury with adjacent tissue involvement i.e., fracture, crush, revascularization, replantation, burn, rheumatic disease. Describing management of the extensor tendon component of these multi-tissue system diagnoses is beyond the scope of this chapter. The intent herein will focus upon management of tendon discontinuity only, generally via sharp or blunt trauma.
Extensor tendon rehabilitation restoration seeks to restore optimal hand AROM. This is a complex endeavor. Effective management requires appreciation of the biomechanics of the hand based on a knowledge of the intricate anatomy (https://www.handsurgeryresource.org/extensor-tendon-laceration) and balance of structures. The extensor system, with its 9 separate zones (link to: Pathoanatomy Photos and Related Diagrams Extensor Tendon Zones and 6 Extensor Compartments Zones: https://www.handsurgeryresource.org/extensor-tendon-laceration), necessitates clinical problem solving for management of injury at each zone.
Our current interventions with post-surgical management of tendon injury involve, as always, an understanding of tissue/wound healing. In particular, the therapist must appreciate the rate of tendon healing in the context of each patient (Peacock EE Jr.), of each surgeon’s technique and of each zone. While in times past, clinicians employed weeks of immobilization to ensure tendon continuity, we now use our understanding of these multiple factors to stage strategic mobilization. Understanding that 3-5 millimeters of tendon glide (also sometimes called Short-Arc-Motion or SAM (Evans)) can minimize tendon adhesion formation if performed regularly and can, ultimately, optimize outcomes.
Therapist management includes:
- Pain Management
- Edema management
- Wound management
- Application/fabrication of specific and often sequential orthoses
- Strategic instruction in exercise/activity appropriate to healing stage to optimize tendon glide and joint ROM while protecting the healing tendon
- Identification of ADL challenges and provision of short term adaptations
Therapists must guide their patients to maintain all safely possible PROM of joints adjacent to the injury/repair to minimize unnecessary stiffness of technically uninvolved fingers. The interconnections between the extensor tendons to multiple fingers can make this endeavor challenging.
Indications for Intervention
Any disruption of extensor tendon continuity will require intervention.
Evaluation to Determine Need for Intervention
Generally, the physician referral determines the need for intervention. ROM and pain assessment may also reveal a previously undiagnosed extensor tendon continuity issue.
Intervention Options
The zone of injury determines intervention options as well as whether the treating provider opted for conservative or surgical management. As stated above, clinicians have employed either immobilization or mobilization treatment approaches or a combination of the two.
THERAPIST CONSERVATIVE INTERVENTIONS FOR ZONE III & IV EXTENSOR
TENDON INJURY
Zone III Extensor Tendon Injuries: Acute; Closed
For acute injuries—Tubiana and Burton Stage 1—therapy seeks to re-establish continuity of the central slip insertion at the PIPj via joint positioning and approximation of the tendon ends. This anatomic achievement will retain the dorsal axis of rotation of the lateral bands at the PIPj and reduce the deforming forces at the PIPj and DIPj. Initial treatment consists of orthosis management to position the MPj, PIPj joints paired with AROM to the DIPj.
Chinchalkar (2024) recommends:
0-2 weeks: (orthosis image 1 hand based & image 2 finger based)
—MCPj comfortably flexed,
—PIPj in full extension,
—DIPj free for AROM
2+-6 weeks:
—With the MPj comfortably flexed, initiate gentle PIPj AROM
—Assess the patient’s ability to actively extend to neutral vs the presence of a lag (a
“lag”is the difference between the ROM achieved passively and that achieved actively)
—Continue PIPj in full extension between exercise sessions
—DIPj free for AROM
Placing the MPj in flexion helps to determine PIPj PROM in extension. MPj flexion causes relaxation of the long flexors and intrinsics. In addition, the lateral bands translate dorsally with MPj flexion. With MPj flexion posture, extrinsic extensor force translates distally to add strength to extension. Leaving the DIPj free during orthosis wear allows active DIPj flexion. (orthosis image 3)
This motion facilitates serial oblique reticular ligament (SORL) length retention, FDP gliding and dorsal translation of lateral bands. DIPj AROM maintains the relationshipbetween the transverse reticular ligament (TRL) and the triangular ligament (TL). Finally it prevents DIPj dorsal capsular tightness. Recalcitrant extensor lag after initial management can occur due to sub-tendinous adhesions. A relative motion orthosis (RMO) (Merritt) with MPj in flexion (orthosis image 4A and video 4B) can treat extensor lag and facilitate restoration of complete PIP extension. Soft tissue manipulation during active extension including downward pressure on the tendon coupled with either proximal traction of the tendon during active extension or distal traction of the tendon during active flexion has also demonstrated clinical efficacy.
After thorough evaluation, therapists may still consider the above described treatment even in the face of “late” presentation of what seems to be central slip discontinuity. In this situation, the term “late” has no precise definition for length of time post injury. Chinchalkar (personal communication, 9/24) states that injuries presenting more than 2 weeks after onset will likely undergo tissue changes that could mandate surgical intervention for an optimal outcome. To clarify the condition of specific structures, Chinchalkar recommends performing the comprehensive and sequential evaluation described below.
Following active range of motion (AROM) for IP flexion and extension, the evaluator passively extends the PIP and observes whether the patient can maintain PIP extension and, if so, for how long. If the patient can maintain some extension even for a short period, this suggests that the intrinsics still have the capability to extend the joint via the lateral bands because they still have an orientation dorsal to the axis of rotation of the PIP joint. However, in the absence of central slip continuity, the patient will be unable to initiate and maintain this lateral band dorsal orientation
The Bouviers test (https://www.handsurgeryresource.net/bouviers) involves passively flexing the MPj joint while observing the patient’s ability to actively extend the PIPj. The therapist can pair this MPj flexion with passive IP extension and observe for the ability to maintain PIPj extension. A positive result may indicate a central slip discontinuity.
The clinician assesses the function of the spiral oblique retinacular ligament (SORL) with a combination of passive MPj flexion and passive PIPj extension while observing AROM of the DIPj joint. A lack of or decreased flexion at the DIPj suggests a shortening of this ligament. This shortening likely results due to prolonged flexion of the PIPj, due to an imbalance in the finger's extensor mechanism
Chinchalkar (2024) describes an innovative assessment using a DIPj flexion orthosis on a finger that lacks PIPj extension. If the orthosis enables the patient to achieve increased PIPj extension, this suggests triangular ligament attenuation. The orthosis works by positioning the lateral bands closer to the PIPj axis of rotation, enhancing the likelihood of extension.
Feasibility of Relative Motion Orthosis (RMO) Management
Chinchalkar (2024) has demonstrated via cadaver dissection that even with an RMO in place, full PIPj flexion in the presence of central slip discontinuity will result in gapping of the central slip. This will ultimately cause a gap scar to form and render the central controlling arm (central slip) extensor mechanism too long to counterbalance flexor forces and achieve full extension. An attenuated extensor mechanism will be too long to perform full extension. In addition, Chinchalkar points out that the RMO will not be effective in the following situations:
—Presence of gap scar at tendon coaptation
—Attenuation of triangular ligament
—Contractures of SORL, transverse reticular ligament, volar plate and accessory
collateral ligaments
—DIPj dorsal capsular tightness
Management of Central Slip Surgical Repairs
Surgical repairs at this level may consist of isolated central slip repair or include lateral band repair, depending on which structures lack continuity. Post-surgery management will vary with the repaired structures. Mobilization scheduling at each joint will need to respect the stress each tendon component can tolerate. Chinchalkar (2024) makes the following tendon management recommendations. Soon after isolated central slip repair, the therapist instructs the patient in active 30° PIP flexion and extension SAM. On a weekly basis, the SAM range adds 15° of PIP motion.
The patient also performs DIP blocking exercises—that is—DIP AROM with the PIP blocked in extension. (Orthosis Image 5) The therapists monitors for extensor lag and for the formation of a PIP flexion contracture. The patient avoids forceful composite finger flexion for 6-8 weeks.
Following central slip repair in conjunction with lateral band repair, the patient may start SAM of the PIPj at 30° increasing weekly by 15° increments but must avoid any DIPj motion for 3 weeks (Chinchalkar 2024). At this point post surgery, the regimen may initiate DIPj SAM (30° flexion and active extension). On a weekly basis, the patient adds 15° flexion ROM of DIPj motion.
Therapists can apply a RMO with the MPj in flexion in conjunction with progressive SAM PIPj ROM to accompany management of central slip repairs with or without lateral band repair. The surgical repair will minimize gap scar and the subsequent soft tissue abnormalities. The use of the RMO may facilitate tendon gliding since it transfers additional force to lengthen adhesions.
ZONE IV REPAIRS
While relatively rare, Zone IV injuries require anatomic discernment and relevant treatment applications. Chinchalkar (2024) advises the analysis of the segment of the Zone IV tendon involved and therefore to identify which structures have lost continuity as well as those that the surgeon has repaired. If the injury occurs just proximal to the PIPj, the injury likely would involve only the central slip. To manage discontinuity at this level, the therapist applies a regimen similar to that of a zone III injury. When an injury occurs mid proximal phalanx, the injury could involve the central slip and lateral bands. Initial management for this type of injury, with lateral band involvement, requires an immobilization orthosis with the IPs in full extension.(image 6) During the first week post surgery, the patient begins short arc isolated active flexion to 45°, 30° of active PIPj and DIPj to 15°. With initial PIPj mobilization, the DIPj remains in neutral via orthosis stabilization.Serial custom template orthoses can guide the PIPj progressive flexion motion arcs of 15° increments each week. (Evans & Thompson) At 4-6 weeks, the patient can begin gradually increasing combined motion of all 3 joints. The therapist monitors and treats extensor lag and PIP flexion contracture. Strengthening begins at 8 weeks post surgery. To facilitate independent tendon glide, prescribed exercises mobilize EDM and EIP separately from EDC. Multiple finger involvement requires fabrication of an elastic tension extension orthosis (reverse Kleinert).(orthosis image 7 hand based & 8 FA based)
A dorsal proximal phalanx injury distal to the MCPj, most likely involves the EDC. Management can employ an ICAM orthosis or RMO. Index and small finger injury at this level requires isolated gliding exercises to the EIP or EDM from EDC respectively.
Acknowledgements
We acknowledge Shrikant Chinchalkar MThO BScOT OTR CHT for his contributions to this chapter. He has provided information via published articles, lectures and personal communication.
