Supplementary axial Kirschner wire fixation for crescentic and Ludloff proximal metatarsal osteotomies: a biomechanical study

Comparison between Pin Fixation and Combined Screw Fixation in Proximal Chevron Metatarsal Osteotomy for Hallux Valgus Deformity Correction

Background

Problems associated with hallux valgus deformity correction using Kirschner-wire (K-wire) fixation include pin pullout and loss of stability. These complications are pronounced in the osteopenic bone, and few reports have focused on pin versus screw fixation. We examined the use of additional screw fixation to avoid these problems. The aim of this study was to compare outcomes of K-wire fixation (KW) and a combined K-wire and screw fixation (KWS).

Methods

Two groups with hallux valgus deformity, who were treated with a proximal chevron metatarsal osteotomy (PCMO), were compared based on the fixation method used. The KW group included 117 feet of 98 patients, and the KWS group included 56 feet of 40 patients. Clinically, the preoperative and final follow-up visual analog scale (VAS) pain score, American Orthopedic Foot & Ankle Society (AOFAS) hallux score, and patient satisfaction score were evaluated. Radiographically, hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured.

Results

The mean VAS score decreased from 6.3 preoperatively to 1.6 postoperatively in the KW group and from 5.7 preoperatively to 0.5 postoperatively in the KWS group (p < 0.001). The mean AOFAS scores of the KW and KWS groups improved from 59.4 and 58.2, respectively, to 88.9 and 95.3, respectively (p < 0.001). Eighty-five percent in the KW group and 93% in the KWS group were satisfied with surgery. Clinical differences were not significant. The mean HVAs decreased from 34.7° to 9.1° in the KW group and from 38.5° to 9.2° in the KWS group (p < 0.001). The mean IMA decreased from 14.5° (range, 11.8°–17.2°) to 6.4° (range, 2.7°–10.1°) in the KW group and from 18.0° (range, 14.8°–21.2°) to 5.3° (range, 2.5°–8.1°) in the KWS group (p < 0.001). When IMA values at the 3-month postoperative and the final follow-up were compared, the IMA was significantly increased only in the KW group (p < 0.001) and no difference was found in the KWS group (p = 0.280).

Conclusions

We found a statistically significant difference in the decrease in IMA between the 2 groups. We recommend the combined pin and screw fixation in PCMO to enhance fixation stability and prevent potential hallux valgus correction loss.

Supplementary medial locking plate fixation of Ludloff osteotomy versus sole lag screw fixation: A biomechanical evaluation

BACKGROUND

The Ludloff oblique osteotomy is inherently unstable, which might lead to delayed union and loss of correction. Supplementary fixation to two lag screw fixation has been proposed. The hypothesis is that the osteotomy fixation constructs supplemented by a mini locking plate provide greater resistance to osteotomy gaping and loss of angular correction in response to cyclic loading.

METHODS

Twenty fourth generation composite 1st metatarsals were used and underwent a Ludloff osteotomy. They were divided in two fixation groups: two lag screws (Group A), and with a supplementary mini locking plate (Group B). Specimens were subjected to either monotonic loading up to failure or to fatigue (cyclic) tests and tracked using an optical system for 3D Digital Image Correlation.

FINDINGS

The osteotomy gap increased in size under maximum loading and was significantly greater in Group A throughout the test. This increase was observed very early in the loading process (within the first 1000cycles). The most important finding though, was that with the specimens completely unloaded the residual gap increase was significantly greater in Group A after only 5000cycles of loading up to the completion of the test. The lateral angle change under maximum loading was also significantly greater in Group A throughout the test, with that increase observed early in the loading process (5000cycles). With the specimens completely unloaded the residual lateral angle change was also significantly greater in Group A at the completion of the test.

INTERPRETATION

Supplementary fixation with a mini locking plate of the Ludloff osteotomy provided greater resistance to osteotomy gaping and loss of angular correction compared to sole lag screws, in response to cyclic loading.

Correction of moderate to severe hallux valgus with isometric first metatarsal double osteotomy

BACKGROUND

The operative treatment for the moderate to severe bunion continues to present challenges. The indications for a single, double, or triple first ray osteotomy remain controversial. In addition, it is not clear whether an opening wedge osteotomy leads to clinically relevant arthritis at the first metatarsophalangeal joint. However, it is this theoretical concern that has led the authors to develop an isometric correction of the first ray.

METHODS

Thirty-two patients underwent operative correction of hallux valgus with a double osteotomy of the first metatarsal using an opening wedge proximally and a closing wedge distally. The mean follow-up period was 59.3 months with a range of 55 to 65 months.

RESULTS

The 1-2 intermetatarsal angle preoperatively was a mean of 18.9 degrees (range 17-23), correcting postoperatively to a mean angle of 8.6 degrees (range 5-12), for an average correction of 10.4 degrees (range 6-16). The postoperative AOFAS scores were 39.4 out of 40 points for pain, 42.4 out of 45 points for function, and 15 points for alignment. The total score was excellent with 94.2 out of 100 possible points. Radiographic union occurred in all cases. There was one case of painful edema of the foot and two cases of early avascular necrosis (AVN) diagnosed by residual pain at the hallux metatarsophalangeal joint and transient osteopenia of the metatarsal head on radiographs. No late sequelae associated with AVN such as arthritis or metatarsal head collapse were noted with long-term follow-up. These healed within months without specific treatment.

CONCLUSION

A double osteotomy of the first metatarsal with a nonlocking, low-profile plate was an effective procedure for correcting severe hallux valgus that carried a low complication rate and high patient satisfaction. It has clear advantages over isolated opening wedge procedures, including potentially better correction especially in those bunions associated with an increased distal metatarsal articular angle.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

The Ludloff osteotomy: a review of current concepts

The Ludloff osteotomy is a technique option to address hallux valgus in patients with a moderately to significantly increased first-second intermetatarsal angle. The Ludloff osteotomy is an oblique osteotomy of the first metatarsal extending dorsal-proximal to plantar-distal when viewed in the sagittal plane. The dorsal-proximal portion of the metatarsal is cut with the saw while maintaining the plantar-distal surface intact. A screw is inserted across the proximal aspect of the osteotomy, then the osteotomy is extended across the plantar surface distally. The metatarsal is rotated around the axis of the screw to the desired correction. In order to perform the osteotomy correctly, the surgeon must not only effectively complete the nuances of the technique, but also understand the limitations and contraindications of the Ludloff osteotomy. This review of current concepts for the Ludloff osteotomy reviews recent literature as well as technique pearls and pitfalls in the application of this powerful osteotomy.

Additional surgical factors affecting the recurrence of hallux valgus after Ludloff osteotomy

We reviewed 91 patients (103 feet) who underwent a Ludloff osteotomy combined with additional procedures. According to the combined procedures performed, patients were divided into Group I (31 feet; first web space release), Group II (35 feet; Akin osteotomy and trans-articular release), or Group III (37 feet; Akin osteotomy, supplementary axial Kirschner (K-) wire fixation, and trans-articular release). Each group was then further subdivided into severe and moderate deformities.

The mean hallux valgus angle correction of Group II was significantly greater than that of Group I (p = 0.001). The mean intermetatarsal angle correction of Group III was significantly greater than that of Group II (p < 0.001). In severe deformities, post-operative incongruity of the first metatarsophalangeal joint was least common in Group I (p = 0.026). Akin osteotomy significantly increased correction of the hallux valgus angle, while a supplementary K-wire significantly reduced the later loss of intermetatarsal angle correction. First web space release can be recommended for severe deformity. Additionally, K-wire fixation (odds ratio (OR) 5.05 (95% confidence interval (CI) 1.21 to 24.39); p = 0.032) and the pre-operative hallux valgus angle (OR 2.20 (95% CI 1.11 to 4.73); p = 0.001) were shown to be factors affecting recurrence of hallux valgus after Ludloff osteotomy.

Cite this article: Bone Joint J 2013;95-B:803–8.

Medial locking plate versus screw fixation for fixation of the Ludloff osteotomy

A prospective cohort study of the Ludloff osteotomy, stabilized with either lag screws or a locking plate, was undertaken from May 2001 to November 2010, involving patients treated for hallux valgus with a first intermetatarsal angle greater than 15°. All patients were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) and Roles and Maudsley scores before and after surgery. The cohort included 119 procedures in 112 patients, 91 (76.47%) of which were fixated with lag screws and 28 (23.53%) with locking plates. The participants were categorized as active (n = 69 procedures) or athletic (n = 50 procedures). The overall mean patient age was 45.5 ± 14.2 years. No statistically significant differences were found between the fixation groups relative to age, preoperative AOFAS and Roles and Maudsley scores, and postoperative AOFAS scores. Postoperatively, the mean Roles and Maudsley score for the lag screw group was 1.8 ± 0.6 and that for the locking plate group was 2.2 ± 0.7 (p < .009). In both groups, the AOFAS scores improved significantly (p < .0001) after surgery. The mean interval to return to activity in the athletes was 3.6 ± 1.1 months and was 3.9 ± 1.2 weeks in the active group (p = .16). Also, 4 of the active patients (5.8%) failed to return to their desired activity level. Overall, 6 (5%) recurrent hallux valgus deformities were observed, 5 (4.2%) in the lag screw group and 1 (.8%) in the locking plate group (p = .57). Of the 6 recurrences, 5 occurred (4.2%) in patients older than 50 years (p = .05).

Mechanical comparison of two types of fixation for ludloff oblique first metatarsal osteotomy

The Ludloff oblique metatarsal osteotomy is an effective method to correct hallux valgus deformity, although a number of problems have been associated with it, including inherent instability, delayed union, dorsal malunion, and fixation failure. The purpose of the present study was to compare the mechanical characteristics of fixation of the Ludloff osteotomy in 20 identical synthetic bone models, 10 fixated using 2 screws (group I) and 10 fixated using 2 screws augmented with a mini locking plate (group II). Each specimen was loaded to failure, and the mean average load to failure, stiffness, and absorbed energy to failure were compared using unpaired Student's t test. The mean average stiffness of the Ludloff osteotomy fixed with 2 screws (group I) and with the supplementary mini locking plate (group II) was 172.7 ± 31.7 N/mm and 193.3 ± 39 N/mm, respectively (p = .21). The mean average load to failure for groups I and II was 278.4 ± 64.4 N and 356.2 ± 77.9 N, respectively (p = .025). The mean average energy absorbed before failure for groups I and II was 506.7 ± 206.4 Nmm and 769.8 ± 339.4 Nmm, respectively (p = .05). The use of a medially applied supplementary mini locking plate offers a simple and effective method to improve the mechanical stability of the Ludloff oblique osteotomy.

Technical tip: the crescentic shelf: a modified Ludoff osteotomy

Level of Evidence: V, Expert Opinion

Prospective comparative study of the scarf and Ludloff osteotomies in the treatment of hallux valgus

BACKGROUND

This study compares two diaphyseal osteotomies (scarf and Ludloff) which correct moderate to severe metatarsus primus varus. This is a single surgeon, prospective cohort study with clinical and radiological follow~up at 12 months.

MATERIALS AND METHODS

There were 57 patients in each group. Both groups were similar in terms of age, gender and preoperative deformity. Clinical assessment included visual analogue scale questionnaires for subjective assessment and functional activities and the American Orthopaedic Foot and Ankle Society (AOFAS) score. Standardized weight bearing radiographs were analyzed.

RESULTS

There was no statistically significant difference between the two groups at 6 and 12 months in subjective satisfaction, AOFAS score, improvement in functional activities and range of movements. The improvement in pain (at best) and transfer lesions at 12 months was significantly better in the scarf group (p < 0.05). The radiological results at 6 and 12 months including intermetatrsal angle (p < 0.001), hallux valgus angle (p < 0.01), distal metatarsal articular angle and seasmoid position (p < 0.05) were significantly better in the scarf osteotomy group. There were three cases (5%) of delayed union in the Ludloff group. Two of these healed with dorsiflexion malunion. One patient in the Ludloff osteotomy group developed a complex regional pain syndrome. There were two wound complications in the scarf group.

CONCLUSION

Overall the patients who had a scarf osteotomy had a superior outcome at 6 and 12 months.

Intermediate-term results of the Ludloff osteotomy in one hundred and eleven feet. Surgical technique

BACKGROUND

The modified Ludloff proximal first metatarsal osteotomy is indicated for the surgical correction of moderate-to-severe hallux valgus deformity associated with metatarsus primus varus. We report the intermediate-term results of this procedure.

METHODS

Ninety-nine patients (111 feet) with a mean age of fifty-six years underwent a modified Ludloff proximal first metatarsal osteotomy and a distal soft-tissue procedure at two institutions for the treatment of a moderate-to-severe hallux valgus deformity. The American Orthopaedic Foot and Ankle Society score and weight-bearing radiographs of the foot were assessed preoperatively and after a mean duration of follow-up of thirty-four months. Clinical and radiographic outcome was also compared between younger and older patients, with the arbitrarily chosen age of sixty years dividing the two groups.

RESULTS

The mean American Orthopaedic Foot and Ankle Society score improved significantly (p < 0.0001) from 53 points preoperatively to 88 points at the time of the most recent follow-up. The mean American Orthopaedic Foot and Ankle Society score for patients who were sixty years of age or less was significantly higher than that for patients who were more than sixty years of age (91 compared with 83 points; p = 0.0057). The mean hallux valgus angle decreased significantly from 35 degrees preoperatively to 9 degrees at the time of the most recent follow-up (p < 0.0001), and the mean intermetatarsal angle decreased significantly from 17 degrees to 8 degrees (p < 0.0001). All osteotomy sites united without dorsiflexion malunion but with a mean first metatarsal shortening of 2.2 mm.

CONCLUSIONS

To our knowledge, the present report describes the largest cohort of patients undergoing a modified Ludloff osteotomy for the correction of hallux valgus deformity that has been reported in the literature. Our intermediate-term results demonstrate that the procedure achieves significant correction of moderate-to-severe hallux valgus deformity, significant reduction in forefoot pain, and significant improvement in functional outcome. Patients with an age of sixty years or less appear to have a more favorable outcome.

Differences in the mechanical properties of calcaneal artificial specimens, fresh frozen specimens, and embalmed specimens in experimental testing

BACKGROUND

Artificial calcanei, fresh-frozen cadaver specimens, and embalmed cadaver specimens were compared in experimental testing under biocompatible loading to clarify the biocompatibility of artificial calcaneal specimens for implant testing.

METHODS

Two different artificial calcaneal bone models (Sawbone, Pacific Research Laboratories, Vashon, WA, and Synbone, Synbone Inc., Davos, Switzerland), embalmed cadaver calcaneal specimens (bone density, 313.1 +/- 40.9 g/cm2; age, 43.8 +/- 7.9 years), and fresh-frozen cadaver calcanei (bone density, 238.5 +/- 30.0 g/cm2; age, 44.4 +/- 8.2 years) were used for testing. Seven specimens of each model or cadaver type were tested. A mechanical testing machine (Zwick Inc., Ulm, Germany) was used for loading and measurements. Cyclic loading (preload 20 N, load was increased every 100 cycles by 100 N from 1,000 to 2,500 N, 0.5 mm/s) and load to failure (0.5 mm/s) were performed. The loads were applied through an artificial talus in a physiological loading direction. The displacement of the posterior facet in the primary loading direction was measured.

RESULTS

The four different specimen groups showed different stability and different displacement in the primary loading direction during cyclic loading. The variation of the maximal displacement in the primary loading direction for the entire cyclic loading was higher in artificial specimens than in the cadaver specimens.

CONCLUSIONS

Artificial calcanei (Sawbone, Synbone) showed different biomechanical characteristics than cadaver bones (embalmed and fresh-frozen) in this experimental setup with biocompatible cyclic loading. These results do not support the use of artificial calcanei for biomechanical implant testing. Fresh-frozen and embalmed specimens seem to be equally adequate for mechanical testing. The low variation of mechanical strength in the unpaired cadaver specimens suggests that the use of PAIRED specimens is not necessary.