Radiographic Evaluation of Hallux Valgus — UW Radiology

posted on 17 Mar 2014 21:19 by cojimmie
Radiographic Evaluation of Hallux Valgus — UW Radiology

Michael L. Richardson, M.D.
Sigvard T. Hansen, M.D.
Ray F. Kilcoyne, M.D.


Departments of Radiology and Orthopaedic Surgery
University of Washington





Introduction


Hallux valgus is a common foot disorder of several etiologies, whichcan lead to significant foot pain and deformity. Little has been publishedin the radiographic literature about the pre- and postoperative radiographicfindings of this very common and very treatable cause of foot pain.







Definition


The term hallux valgus denotes deviation of the great toe toward thefibular border of the foot. Hallux valgus is not synonymous with bunion,which is derived from the same root as "bun" or "bunch",and means an area of swelling. In connection with the foot, bunion usuallyrefers to the prominent medial portion of the first metatarsal head andespecially to the bursa or a bursa plus osteophyte over it, when this exists.A bursa and/or osteophyte may or may not accompany hallux valgus.







NlFoot:

HValgus:

normal foot in which the normal intermetatarsal anglemeasures about 5 - 10 degrees

foot with metatarsus primus varus, in which the intermetatarsalangle measures about 20 degrees








Pathogenesis


The etiology of hallux valgus is somewhat controversial. Some cases arecongenital, perhaps secondary to a sloping surface of the first tarsometatarsaljoint. When this joint is hypermobile, with or without the normal angle,it is often referred to as an "atavistic" tarsometatarsal joint.Other cases are almost certainly due to environmental factors, such as poorlyfitting footwear. The fashionable shoes worn by many women are more constrainingthan the shoes worn by men and are felt by many authors to be the etiologicfactor in most cases of hallux valgus. This would help to explain the 10:1ratio of females to males seen with this disorder.




Flats:



25 year old female with normal feet and no shoes.





Heels:



Same patient as figure above, but now in shoes with 3 inchheels. The intermetatarsal angle has widened in both feet, and a functionalhallux valgus has developed, due to her constricting shoes.





NoHiHeels:










Radiographic Findings


Hallux valgus is often associated with abnormalities in two planes. Insuch cases, the first metatarsal head is not only deviated medially, butalso dorsally. As the first metatarsal splays dorsally, greater stress isplaced on the central metatarsals, especially the second, leading to hyperostosisand occasionally stress fractures.







HappyMT:



Normal foot







UnHappyMT:



Foot with metatarsus primus varus. Dorsal splaying of boththe first and fifth metatarsal heads is noted. Keratosis (dark pink) is seen in the skin adjacent to these heads, due to pressure against the shoe.The central metatarsal heads now bear more of the weight, leading to plantarkeratosis and hyperostosis.





NlLatFoot:



Normally, the 1st and 2nd metatarsals are parallel to eachother, and their superior surfaces appear within 1 - 2 mm of each other,as shown here.









MPVLatFoot:



Some patients with metatarsus primus varus demonstrate notonly medial angulation of the first metatarsal head, but also dorsal angulationas well. Here the first metatarsal is elevated several mm above the secondmetatarsal head.









Sesamoid:



Two large sesamoid bones are present beneath the first metatarsophalangealjoint within the tendons of the flexor hallucis brevis. With the developmentof hallux valgus, the 1st metatarsal head migrates medially and dorsally.The fibular sesamoid frequently rotates slightly dorsally, and is seen onthe AP film in profile.









BilatHV:



This patient has a marked hallux valgus deformity in bothfeet. As the first toe migrates more and more to valgus, it presses againstthe second toe, and may aggravate dorsal clawing of the second toe, whichis usually initiated by overload of the second metatarsal and synovitisof the metatarsophalangeal joint. Also note the relative hyperostosis ofthe second metatarsal shafts compared to the third and fourth, as well asdorsal rotation of the fibular sesamoids.









CalBursitisDetail:



This patient exhibits soft tissue swelling medial to her firstmetatarsal head, indicative of bursitis and synovial thickening. Also notedis dystrophic calcification in this bursa. Such changes could also be seenin tophaceous gout.









PreOp:

Preoperative film showing hallux valgus and clawtoe deformitiesof the second and third toes. Medial subluxation of the head off the sesamoidsis shown, as well as marked hyperostosis of the second metatarsal shaft.









PostOp:



Same patient status post Lapidus procedure. With osteotomyof the 1st metatarsal, the 1st metatarsal head has been realigned in a morelateral and plantar location over the sesamoids. The 1st tarsometatarsaljoint has been fused. Kirschner wires are seen in the 2nd and 3rd toes afterosteotomy for clawtoe deformities.









Broken:



Broken screw following Lapidus procedure. Cancellous screws,especially the thinner ones, usually break at the junction of the shankand the threaded portion. Therefore, this probably represents at least adelayed union if not a nonunion. However, if correct position is maintained,as in this case, and the surgical site is painless, it may be considereda satisfactory result.









HVarus:



This patient has undergone bilateral osteotomy of the medial1st metatarsal heads ("bunionectomy"). Unlike the Lapidus procedure,this procedure does not correct the underlying splaying of the 1st metatarsal,and can lead to instability of the first metatarsophalangeal joint. In thiscase, the hallux valgus has been overcorrected, and the patient now hasa bilateral hallux varus. Bilateral osteotomies are noted in the 5th metatarsalsfor correction of "bunionette" deformities.








CONCLUSIONS



Hallux valgus is a very common and very treatable cause of foot pain.

Hallux valgus cannot be adequately assessed unless weight-bearing viewsare performed in the AP and lateral positions.

With experience, the radiologist can make valuable observations inboth the pre- and postoperative films in patients with hallux valgus.










References

Coughlin MJ. Hallux valgus: causes, evaluation, and treatment. PostgradMed 1984;75:174-178.

Frede TE, Lee KJ. Compensatory hypertrophy of bone following surgeryon the foot. Radiology 1983;146:347-348.

Inman VT. Hallux valgus: a review of etiologic factors. Orthop Clin North Am 1974;5:59-66.

Kelikian H. The hallux. In: Jahss MH, ed., Disorders of the foot. Philadelphia: WB Saunders, 1982:539-621.

Kilcoyne RF, Farrar E. Injuries and deformities of the foot. In: Handbook of radiologic orthopaedic terminology. Chicago: Year Book, 1986:123-137.

Weissman BNW, Sledge CB. The foot. In: Orthopedic radiology. Philadelphia: WB Saunders, 1986:625-670.

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