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Chevron Osteotomy

- Discussion:
- in this procedure, a "V" shaped osteotomy of the distal metatarsal is created, which allows the first
MT head to be shifted laterally, correcting the abnormal shape from long standing valgus drift;
- effect on blood supply:
           - Circulatory disturbance of the first metatarsal head after Chevron osteotomy as shown by bone scintigraphy.
- The effect of chevron osteotomy with lateral capsular release on the blood supply to the first metatarsal head.
- Blood flow to the metatarsal head after chevron bunionectomy.
- Blood Supply to the First Metatarsal Head and Vessels at Risk with a Chevron Osteotomy
- indications:
- for younger patients w/ no joint arthrosis, and w/ mild to moderate hallux valgus deformities (IM angle less than 16 and MTP less than 30-35 deg);
- this might be the procedure of choice for young atheletes;
- elderly patients might not do as well w/ this procedure;
- requirements:
- for pts younger than 50 yrs w/ minimal to moderate deformity;
- pt should have a congruent joint;
- deformity should be passively correctable;
- contraindications:
- significant degree of pronation of the great toe (since this deformity will not be corrected w/ a chevron osteotomy);
- MTP angle > 30-35 deg
- IM angle > 16 deg
- distal metatarsal articular angle of more than 15 deg;
- a Chevron performed on a more excessive angle may cause the 1st MTP joint to impinge on the second MTP joint;
- tight adductors:
- if adductor tightness will require and adductor tenotomy, then a proximal metatarsal osteotomy should be chosen over the chevron
(due to preservation of the metatarsal head blood supply);
- incongruent MTP joint;
- relative contra-indications:
- severe displacement of sesamoids;
- older patients;
- outcomes:
- in the report by Hans-Jorg Trnka et al (JBJS 2000), 57 feet underwent Chevron osteotomies with 5 year follow up;
- passive ROM of the 1st MTP joint decreased between the preop assessment and the 2-year follow-up eval but was
unchanged at the 5-year follow-up evaluation.
- x-ray evaluation showed no changes in the hallux valgus or IM angle between the 2-year and 5-year evaluations,
although the number of feet with arthrosis of the MP joint increased slightly, from eight to eleven;
- patients aged 50 years or older did as well as younger patients;
- authors routinely performed an intra-articular lateral capsular release;
- no osteonecrosis of the metatarsal head was noted at the 2-year or 5-year follow-up evaluation;
- arthritis of the MP joint was noted in 8 feet at the 2-yr follow-up evaluation and in 11 feet at 5-yr follow-up evaluation;
- references:
- The Chevron Osteotomy for Correction of Hallux Valgus. Comparison of Findings After Two and Five Years of Follow-up
- Chevron osteotomy in hallux valgus. Ten-year results of 112 cases.
- Comparison of chevron ostoeotomy and modified Mcbride bunionectomy for correction of mild to moderate hallux valgus deformity.
- Scarf versus Chevron Osteotomy in Hallux Valgus: A Randomized Controlled Trial in 96 Patients
- Comparison of distal soft-tissue procedures combined with a distal chevron osteotomy for moderate to severe hallux valgus: first web-space versus transarticular approach.

- Technique:

(1)    - clically note the HV angle, or trace the foot out on the surgical gloove paper;
- perform a standard lateral approach to the first MTP joint, but avoid excessive periosteal stripping so that the head is not devascularized;
- for this reason rake retractors are used instead of Homan's;
- in addition preserve the anterior and posterior capsular attachments;
- (see blood supply to metatarsal head);

(2)  - excision of medial eminence:
            - typically the medial eminence is removed first (see Silver procedure);
- medial eminence was excised about 2 mm medial to the sagittal sulcus with a sagittal saw
- medial eminence of the head of the first metatarsal was excised parallel with the medial surface of the foot at the groove of Clark

(3) - concomitant lateral release:
            - can be carefully performed, otherwise surgeon risks AVN;
- lateral capsular release can be performed thru the medial incision;
- the capsulotomy should be made distal as possible to avoid transection of the vessels entering the metatarsal head from the lateral side;
- lateral side of the joint capsule is released with use of a number-15 blade
- adductor hallucis tendon was released completely
- varus stress is applied to 1st MP joint to complete the release of the adductor hallucis tendon from proximal phalanx of the great toe
- references:
- Comparison of distal chevron osteotomy with and without lateral soft tissue release for the treatment of hallux valgus
- Comparison of soft-tissue procedures + distal chevron osteotomy for mod to severe hallux valgus: 1st web-space vs transarticular approach.
                    - Distal chevron osteotomy with lateral release for treatment of hallux valgus deformity.

   (4)- chevron ("V") cut is made in the coronal (lateral) plane;
- sharp and thin cutting blade is used to avoid metatarsal head frx;
- osteotomy is made in cancellous bone in order to maximize bony contact (both for bony stability and healing);
- distal end of the Chevron should be 5 mm from the articular surface, w/ the dorsal arm being slightly longer than the plantar arm;
- it is essential however, that the proximal arm of the osteotomy not be made inside the joint capsule;
- rather the cortical cuts need to be made proximal to capsular attachments, which will spare the perforators into the metatarsal head;
- a longer osteotomy cut (more horizontal) will also provide a larger surface area for enhanced stability and healing;
- chevron angle is usually made between 35 and 60 deg (at the apex of the cut);
- if the angle is more than 60 deg, the chevron may become unstable once it is shifted laterally, and is more likely to damage
the blood supply to the metatarsal head;
- osteotomy cut needs to be in true lateral plane (in line w/ the rest of forefoot) or otherwise the metatarsal head will be shift dorsally or plantarly;
- prior to beginning the cut, make a small drill hole in a medial to lateral direction to mark the apex of the deformity;
- small osteotome is used to complete the osteotomy;
- it is also important to avoid penetration overpenetration of the saw through the lateral cortex, so as not to injure the first dorsal metatarsal artery;
- modified-extended chevron osteotomy:
- dorsal arm of the osteotomy is extended far proximally so that the cut exits at proximal metatarsal shaft region;
- allows for angulation at the osteotomy site and greater correction;
- references:
- Correction of moderate to severe hallux valgus deformity by a modified chevron shaft osteotomy.
- Technique Tip: Dorsal Wedge Resection (Uniplanar) in the Chevron Osteotomy for High Distal Metatarsal Articular Angle Bunions

(5) - metatarsal head is shifted laterally;
- secure the metatarsal shaft w/ a towel clip for countertraction;
- about 1 degree of correction is obtained for each 1 mm of lateral translation of the metatarsal head;
- usually 5 mm of displacement is sufficient or 25% of head width (some shift to 9 mm);
- determine whether the lateral shift has improved the HV angle;
- w/ the lateral shift the metatarsal head, the abductor hallucis should be tightened where as the adductor hallucis should be loosened;
- this should help shift the phalanx medially;

(6) - residual (overhanging) metatarsal shaft is removed and is shaved flush;
(7) - fixation of chevron osteotomy;
- if stability is in question, insert two meduallary K wires, from a proximal to distal direction;
- some authors feel that pin fixation is required for all chevron osteotomies;
- consider insertion of two bioabsorbable pins inserted thru separate non-parallel stab incisions from a dorsal to plantar direction;
- advantages: provides stability and allows pins to be buried beneath the skin;
- osteolysis is less common with poly-p-dioxanone (vs polyglycolic acid implants) but when it occurs it is usually clinically insignificant;
- in the study by Crosby L and Bozarth GR (1998), there was no specific advantage to permanent fixation vs temporary fixation
w/ a K wire (or no fixation);
- references:
- Fixation comparison for chevron osteotomies.
- Fixation with bioabsorbable pins in chevron bunionectomy.
- if an adequate correction has not been achieved then perform Akin osteotomy;

   (9)- wound closure:
                   - following the hallux valgus reconstructive procedure, the sesamoids may still lie in a subluxed positioned;
- partial reduction of the sesamoids may be achieved w/ closure of the joint capsule;
- excise the inferior portion of the joint capsule, place the toe in a slightly over-corrected position, and then oppose the inferior
joint capsule to the superior joint capsule w/ non absorbable sutures;
- the goal of this is to de-rotate the sesamoid out of their laterally subluxed position, to a more anatomic position under the metatarsal;
(10) - postoperative care:
                   - gauze or cloth bunion splint (for night use);
- at two weeks, patients are allowed to weight bear as tolerated;

- Complications:
- AVN:
- Malunion
- Excessive shortening (from bone resorption);
- MTP stiffness
- Metatarsalgia (from dorsiflexion at osteotomy site);
- references:
- Complications associated with the Chevron osteotomy.
- Chevron osteotomy: analysis of factors in patients dissatisfaction.

A new osteotomy for hallux valgus: a horizontally directed "V" displacement osteotomy of the metatarsal head for hallux valgus and primus cavus.

The risks and benefits of distal first metatarsal osteotomies.

Treatment of hallux valgus in adolescents by the chevron osteotomy.

Modified chevron osteotomy for hallux valgus.

Comparison of outcomes between proximal and distal chevron osteotomy, both with supplementary lateral soft-tissue release, for severe hallux valgus deformity: A prospective randomised controlled trial.

A comparison of proximal and distal Chevron osteotomy, both with lateral soft-tissue release, for moderate to severe hallux valgus in patients undergoing simultaneous bilateral correction: a prospective randomised controlled trial.