Chevron Group Research Articles

Scarf versus Chevron Osteotomy in Hallux Valgus: A Randomized Controlled Trial in 96 Patients

The degree of correction of hallux valgus deformity using a distal chevron osteotomy is reported as limited. The scarf osteotomy is reported to correct large intermetatarsal angles (IMA). The purpose of this study was to evaluate if one technique gave greater correction of the IMA and hallux valgus angle (HVA) than the other. After informed consent, 96 feet in 83 patients were randomized into two treatment groups (49 scarf and 47 chevron osteotomies). The results were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) Hallux Valgus Scale and radiographic HVA and IMA measurements. At 27 (range 23-31) months followup both groups improved. The AOFAS score in the chevron group improved from 48 to 89 points and in the scarf group from 47 to 91 points. In the chevron group the HVA corrected from 30 to 17 degrees, and in the scarf group the HVA corrected from 29 to 18 degrees. In both groups, the IMA was corrected from 13 to 10 degrees. The differences were not statistically significant. Three patients in the chevron group developed a partial metatarsal head necrosis. In the scarf group, four patients developed grade 1 complex regional pain syndrome compared to one patient in the chevron group. No differences of statistical significance could be measured between the two groups with respect to the AOFAS score, HVA, and IMA. Although both groups showed good to excellent results, we favor the chevron osteotomy because the procedure is technically less demanding.

Prospective, Randomized Comparison of Proximal Crescentic and Proximal Chevron Osteotomies for Correction of Hallux Valgus Deformity

In this study, intermetatarsal angle (IMA) correction, functional outcome, and healing time for the proximal crescentic and proximal chevron osteotomies in moderate to severe hallux valgus deformity were prospectively compared. Seventy-five patients (97 feet) were prospectively randomized to either a proximal crescentic or proximal chevron osteotomy for the correction of moderate to severe hallux valgus deformity with associated metatarsus primus varus. Criteria for study entry included age (adult patients), IMA greater than or equal to 13 degrees, persistent symptoms despite nonoperative treatment, and minimum follow-up of 12 months. Twenty-nine patients (41 feet) in the crescentic group and 37 patients (43 feet) in the chevron group returned for follow-up at an average of 24 and 20 months, respectively. Good results were achieved with both procedures. No statistically significant differences were found with respect to correction of the IMA or to functional outcome between the two groups. Results held true irrespective of patient age, severity of disease, or bilateral involvement. A statistically significant shorter healing time of the first metatarsal was found after proximal chevron osteotomy. Other potential benefits of the chevron procedure included avoidance of dorsiflexion of the first metatarsal, tendency toward less shortening of the first metatarsal, and more medial distribution of tibial sesamoids following surgery, all of which may reduce the potential for development or persistence of transfer lesions.

Evaluation of hallux valgus surgery with dynamic foot pressure registration with the Fscan system

With the advent of microcomputer technology, in-shoe systems for evaluating dynamic plantar pressure are now available. The use of dynamic registration of hallux valgus patients in floor mounted systems has been shown (Betts, Franks and Duckworth 1991). Twenty-four patients were evaluated preoperatively and 25 months after hallux valgus surgery. Fourteen patients (22 feet) were operated with a chevron osteotomy and 9 (9 feet) with a proximal closing wedge osteotomy. They were evaluated clinically and radiographically. The Fscan system, which uses a thin in-sole to measure plantar pressure was used to evaluate pressure under the five metatarsal heads and the great toe. The plantar pressure measurements of 28 normal feet of 14 healthy volunteers were used for comparison. Nine of the chevron operated patients were completely satisfied with surgery compared to four of the proximal. Shoe fitting was improved for most patients in both groups. A correction of 9° in the hallux valgus angle was achieved in the chevron group, significantly greater than in the proximal group. The pressure under specific areas was related to the sum of all the forefoot areas measured. There was significantly lower pressure under the great toe preoperatively in the hallux valgus patients (57%) compared to the normal controls (64%). Surgery did not normalize this. The pressure under the great toe was still reduced and the pressure under the third metatarsal head was increased postoperatively. Dissatisfied patients had a significantly lower great toe pressure both before and after surgery. Four patients with postoperative metatarsalgia had greater pressure under the lateral metatarsal heads and less pressure under the great toe preoperatively. Postoperatively, the great toe still had reduced pressure. Hallux valgus feet differ from normal feet in having less pressure under the great toe which is not normalized by surgery.

Chevron or Wilson metatarsal osteotomy for hallux valgus. A prospective randomised trial

We compared the chevron and the Wilson metatarsal osteotomy for hallux valgus in a prospective randomised trial on 87 feet in 51 patients, reviewed at averages of 5.5 and 38 months after operation. The patients in the chevron group returned to work earlier and mobilised faster, but, at the later review, those in the Wilson group had better functional results and were more satisfied with the appearance of the foot. Correction of the hallux valgus angle was better maintained in patients in the Wilson group and they had a better range of motion at the metatarsophalangeal joint; fewer complained of metatarsalgia.

Comparison of Chevron Osteotomy and Modified McBride Bunionectomy for Correction of Mild to Moderate Hallux Valgus Deformity

The purpose of this study was to compare the results of the Chevron osteotomy to the DuVries' modification of the McBride procedure using identical criteria in two groups of patients. Thirty-two patients (48 feet) that had a Chevron osteotomy and 10 patients (17 feet) who had a modified McBride bunionectomy without metatarsal osteotomy for treatment of mild to moderate hallux valgus were retrospectively reviewed using subjective and objective criteria. Both groups were matched according to age, severity of deformity, and length of follow-up. Ninety-two percent of patients in the Chevron group and 88% of patients in the McBride group responded that they were either totally satisfied or improved regarding pain relief and appearance of the foot following surgery. Chevron osteotomy resulted in a statistically significant greater correction of the intermetatarsal 1-2 angle than did the McBride bunionectomy. Postoperative metatarsophalangeal joint range of motion was not significantly different for the two groups. Following Chevron osteotomy, five (10%) metatarsal heads exhibited radiographic changes of cyst formation and/or increased osteodensity and three (6%) of the osteotomies healed in a malunited position. One of the three metatarsal head malunions occurred in a patient that also had a lateral capsular release, however, none of the five cases that developed radiographic changes in the first metatarsal head was associated with a lateral capsular release. Lateral capsular release with the Chevron osteotomy did not improve the amount of correction of the hallux valgus deformity and it may be a contributing factor to instability at the osteotomy site leading to a valgus malunion.

Developments in petroleum exploration offshore West Greenland in 1978

During the winter of 1977-1978 results to date from all work undertaken in the concession areas offshore West Greenland were thoroughly reviewed by the concessionaires. A negative evaluation had aIready been placed on this area because of the disappointing resuIts from all the wells drilled in 1976 and 1977, in particular the lack of the necessary combination of suitable source rocks and reservoir rocks (Henderson, 1978). After further consideration, companies that had earlier contemplated drilling in 1978 decided against doing so. In the event, the only work undertaken within the concession area was a seismic survey by the Chevron Group in concession 28, amounting to some 341 line kilometres.

Developments Offshore West Greenland in 1978

The only work undertaken in the West Greenland concession areas in 1978 was a seismic survey of 341 km by the Chevron group. The overall negative evaluation placed on these areas by the companies resulted in the relinquishment by year end of 10 of the 13 concessions awarded in 1975.

Developments Offshore West Greenland in 1977

Four wells were drilled offshore West Greenland in 1977 by operators for the Arco, Chevron, and Mobil groups. Three of the wells were drilled on the continental shelf and 1 on the continental slope. All were dry holes. In connection with the drilling activities, extensive physical and biologic environmental studies have been made. Although the sedimentary section is thick, with large structures at depth, none of the wells drilled have found the necessary combination of suitable source and reservoir rocks.

Developments in Greenland in 1976

Total (C.F.P.) completed the first Greenland exploratory well in 1976. Other major activities included preparations by Arco, Chevron, and Mobil groups for their 1977 drilling campaigns. These companies established bases and offices and conducted drill-site and environmental surveys. Three groups recorded limited seismic surveys.

Developments in West Greenland in 1975

Six groups were awarded concessions in West Greenland in 1975. Each group committed to a 5-year work program with a back-away at the end of 3 years. During 1975 the Disko and Chevron groups conducted a geologic field study, all groups recorded geophysical surveys, and the industry jointly sponsored an environmental study. In addition, the Ministry made independent environmental studies. The first well will be drilled in 1976 by Total.