Attenuation, Adhesion and Lags

Extensor Lag at the PIPJ following Extensor Tendon Injury:
Is it Extensor Attenuation or Adherence?
Susan Blackmore MS, OTR/L, CHT
Extensor Lag Defined:
Active extension is less than passive extension. The lag can be due to either an attenuated
extensor tendon, adherent extensor tendon or altered extensor anatomy. It is important to
be able to identify the cause of the extensor lag as the treatments vary depending upon the
cause. Special tests may be difficult to interpret. Other limitations such as flexor tightness
or nerve injury might contribute to limited active extension and need to be ruled out.
DIFFERENTIAL DIAGNOSIS for Limited PIPJ ACTIVE extension
Physical Exam
1. Is there full PIPJ Passive extension?
a. Yes- Continue below
b. No
1. May need to resolve joint stiffness before you are able to fully diagnosis
cause for extension limitations.
2. Evaluate for ORL tightness, volar plate contracture, pseudo boutonniere
deformity.
3. Determine if limitations in PIPJ passive extension is due to flexor
tightness.
4. Rule out changes to the joint (OA, intraarticular adhesions, joint injury)
5. Lateral band volar subluxation
2. Rule out other causes for limited Active PIPJ extension: Low Median or Ulnar nerve
conditions, Lateral band volar subluxation/dysfunction, triangular ligament
rupture/elongation associated with open zone 3 injury.
3. An Attenuated extensor will have" full " digit A/P flexion or the amount of passive
flexion won't vary depending upon proximal joint positions.
4. An Adherent extensor will have limitations in passive flexion, which can increase
when the adjacent joints are also held in flexion.
5. If the lateral bands have adaptively shortened, then passive DIP flexion is least
restricted with the PIPJ and MPJ in flexion. DIPJ flexion will become progressively more
limited as the PIPJ is held in extension and then even less with combined PIPJ extension
and MPJ hyperextension. Lateral band dysfunction can be a secondary result from zone
3 extensor tendon injuries.
6. Review of clinical exam techniques for active extensor deficit: Boyes, Elson, Smith,
Haines-Zancolli. Review the role of Diagnostic Ultrasound. Review of the evidence.
(Soni, Rubin)
WHAT PATIENTS ARE “AT RISK” FOR EXTENSOR LAG?
Types of cases where extensor lag may present:
1. Closed Extensor injury. Failure to identify closed zone 3 or 4 injury often with
volar PIPJ dislocation leads to attenuation. Missed diagnosis may lead to the
progression of a boutonniere deformity.
2. Extensor tendon repair: Incorrect splinting at less than 0 initially. Both
adherence and attenuation can occur after extensor repair.
3. Extensor tendon inflammation in zones 3 or 4 where the tendon becomes
adherent from immobilization associated with inflammation. RA patients may
develop attenuation from synovitis.
4. Any procedure where an incision has been made on the dorsum of the proximal
phalanx, middle phalanx or PIPJ. (adherence or attenuation)
TREATMENT
Prevention of Attenuation for at risk cases
Graded removal of extension support (not full discontinuation) and monitoring for lag for
all diagnoses is extremely important. Advance flexion only if extension is maintained.
1. Closed Extensor injury: Assume a central slip injury if the direction of the PIPJ
dislocation is unknown and pain/stiffness limits physical exam. Immobilize in full
extension until exam can confirm or clear injury to the central slip.
2. Extensor repair Zone 3 and 4: When beginning mobilization, initiate proximal
excursion of the extensor (active extension). Refer to Evans Zone 3
guidelines.(Evans) Orthosis in absolute 0. Advance flexion only if extensor lag
does not increase. When allowed unrestricted motion, gradually decrease use of
extension orthosis. Return to orthosis if lag increases. Consider dynamic PIPJ
extension support or tape placed on digit in full extension as step down orthotic
support. Delay composite digit A/P flexion. Avoid testing passive flexion.
3. Extensor inflammation: See extensor repair. If the patient has RA with
synovitis, consider resting the entire extensor system in an extension orthosis.
Medical management to control inflammation
Once Attenuation is present:
1. Static Orthosis in extension. Wean when lag resolves/ improves.
2. Transition to digit based dynamic extension orthosis (Capner type) and or taping in full
extension.
Advance to:
3. Block full MP Extension with active PIPJ extension. Consider orthoses (Yoke, MP
block) (Lalonde). This may allows the PIPJ to achieve extension and to avoid resting in a
prolonged flexed posture.
4. Slight DIP flexion orthosis used with active PIPJ extension
5. GMIT, motor training
6. There is a delicate balance between extensor lag and need to gain flexion. Delaying
flexion will never disappoint you.
What if the problem is Extensor Adherence?
1. Active extension with proximal joints blocked to direct contractile force at adherent
tendon site with mobilization of soft tissues in the direction opposite to extensor
excursion. The first goal is to reduce adherence through active contraction of extensor
system.
2. Single joint flexion before composite joint flexion. Composite flexion will come!
Composite flexion may stress the healing tendon contributing to tendon gap distal to the
site of adherence instead of facilitating excursion. Avoid testing composite passive
flexion as this may lead to attenuation of the extensor instead of mobilization.
3. Limit PIP flexion to 60 deg. and focus on DIP active flexion. Maintain active
extension. (Gangatharam)
4. Early contraction of extensor and intrinsics as possible. Muscle isolation exercises to
enhance all muscle tendon unit contribution to the extensor expansion.
5. Slight DIP flexion orthosis used with active PIPJ extension to focus glide at the central
tendon.
6. Soft tissue mobilization techniques.
REFERENCES:
1. Evans, R.: Immediate active short arc motion following extensor tendon repair,
Hand Clin 11, 483-510, 1995.
2. Hurlburt PT, Adams BD: Analysis of finger extensor mechanism strain. J Hand
Surg, 20A, 832-840, 1995.
3. Giele H: The functional anatomy and assessment of the extensor mechanism. Br J
Hand Therapy, Vol 11, No. 4, 2006
4. Soni P, Stern CA, Foreman KB et al: Advances in extensor tendon diagnosis.
Plast Reconstru Surg 123, 52e, 2009.
5. Rubin J, Bozentka DJ, Bora W: Diagnosis of closed central slip injuries: A
cadaveric analysis of non-invasive tests. J Hand Surg (Br), 21B, 5, 614-616. 1996.
6. Lalonde DH, Kozin S: Tendon disorders of the hand. Plast Reconst Surg 128, 1e,
2011.
7. Gangatharam S, LeBlanc M: Alternate technique in managing adhesions after
Zone 3 extensor repair: A case report. Tech Hand and UE Surg. Vol 17, No. 1,
46-48, 2013.

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