- See:
-
Diff
Dx: Posterior Ankle Pain:
-
Fractures of Posterior Talar Process:
- Discussion:
- accessory bone found just posterior to talus (accessory ossification
center of the posterior process of the talus);
- it may be considered a non united portion of the lateral tubercle;
- os trigonum is round, oval, or triangular and of variable size;
- present in 2.5% to 14% of normal feet;
- arises from separate ossification center just posterior to lateral
tubercle of posterior talar process;
- it may fuse w/ lateral tubercle or remain as separate ossicle;
- may be injured with forced dorsiflexion injuries - causing disruption of
the synchondrosis bewteen the Os and
the Talus;
-
signs and symptoms:
- symptoms are worse when she assumes the en pointe position
- tenderness to palpation at posterolateral aspect of ankle
posterior to the peroneal tendons which is
made
worse with passive plantar flexion;
- operative management through a medial approach;
- Radiographs:
- edges appear smooth, with dense cortical bone;
- need to distinguish between ossicle &
frx of lateral tubercle;
- MRI:
- look for fluid surrounding the Os and associated marrow edema
(absence of talar marrow edema)
- if there is marrow edema in the talus then consider
posterior talar process fracture;
- in the report by
Sopov et al
of 99mTc methylene-diphosphonate (Tc-MDP) in the os
trigonum region seen on bone scintigrams of soldiers
on active duty;
- radionuclide whole-body skeletal imaging and physical examination
of the foot were carried out in
100
consecutive soldiers on active duty referred for evaluation of suspected
stress-injury of the lower
limbs,
back pain, and different skeletal trauma;
- lateral radiographs of the foot were performed in those with
increased uptake of Tc-MDP at the site of
os
trigonum;
- among 200 feet, 27 (13.5%) showed an increased uptake of Tc-MDP in
the os trigonum region;
- right side was affected in six patients, the left side in 11 and
five patients had bilaterally increased uptake;
- on X-rays, 31 of 44 feet showed the os trigonum. Only 10 of these
27 feet (37%) had a symptomatic
os
trigonum;
- increased uptake of Tc-MDP in the os trigonum region is a frequent
finding among active soldiers and is
of
limited value in detecting symptomatic os trigonum;
- Bone scintigraphic findings of os trigonum: a prospective study of
100 soldiers on active duty.
Sopov V, Liberson A, Groshar D Foot Ankle Int 2000
Oct;21(10):822-4 Related Articles, Books
- Posterior Compression Syndrome:: (see:
diff dx);
- arises from forced plantar flexion in Ballet dancers;
- impingement of posterior aspect of talus between tibia & calcaneus may
cause block to plantar flexion;
- results in painful lateral compression between calcaneus and posterior
aspect of tibia;
- forceful passive plantar flexion should reproduce the patients symptoms;
- in contrast, both FHL tendinitis and posterior tibial tendinitis
cause posteromedial tenderness;
- a differential lidocaine/steroid injection (injected laterally at the
posterior process of the calcaneus) should
relieve symptoms;
- note that this condition may occur along with
FHL
tendonitis;
-
non-operative treatment:
- local steroid injections can be effective;
- cast immobilization might reduce soft tissue swelling, but it will
not reduce block to motion;
- operative treatment:
- excision of bony block will often improve motion and eliminate
pain;
- for isolated posterior impingement, consider lateral approach;
- performed at the level of the ankle joint, just posterior to the
peroneal tendons;
- identify the sural nerve and the FHL tunnel;
- after a capsulotomy has been performed, identify the os trigonum or
the offending osteophyte;
- an adequate decompression should allow the foot to be plantar
flexed w/ no bony impingement;