- 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.
The risks and benefits of distal first metatarsal osteotomies.
Treatment of hallux valgus in adolescents by the chevron osteotomy.