1 Introduction

The majority of patients with fractures of the metacarpal bones (MB) still receive conservative treatment using closed manual reposition and immobilization with plaster splints.¹ In this case, due to insufficient stability, fragments are often (in 24–27% of cases) displaced at an angle and along the axis. As a result, MBs heal in a wrong position – in the form of an angle open to the palm, with rotationally altered coaxial alignment of the fragments.^2,3

As a result, after fracture consolidation, patients complain of pain in the hand, aggravated by exertion, a decrease in the volume of movements in the joints of the fingers and aesthetic discomfort. These impairments are believed to be caused by MB head shifted towards the palm.^4,5 The imbalance between the extrinsic and intrinsic groups of the hand muscles causes a decrease in the strength of the hand grip.⁶

MB shortening, associated with angular deformation, also impairs the function of the hand. It is known that MB shortening by 2 mm leads to a limitation of the extension of the proximal phalanx by 7°.⁷ When MB is shortened by 5 mm, the coaxial alignment of the metacarpophalangeal joint is impaired, the flexion force decreases and pain in the projection of the corresponding radial bone appears during exercise.⁸ Angular deformation of the MB diaphysis by more than 20° normally requires surgical correction. The main method of surgical treatment for such deformation is corrective osteotomy in combination with osteosynthesis.^9–11,17

We have developed a new technique for the correction of MB deformations, which consists of a V-shaped osteotomy, open reposition and plate osteosynthesis, which has the RF patent No. 2651893 of February 20, 2019. The purpose of the study is to evaluate the results of surgical treatment in patients with post-traumatic MB deformations according to the developed method.

2 Materials and methods

From November 01, 2012 to November 01, 2018, five patients with malunited MB fractures were under our observation. The mean age of the patients was 24.2 years (from 15 to 39 years). Four patients had deformations in the fifth MB and one had a deformation in the fourth MB. The mean angle of the MB deformation was 34.8°. The mean time after injury to reconstructive surgery was 2.5 months (from one to five months). Indications for surgery included patient dissatisfaction with the appearance of the damaged hand, limited mobility of the fingers, reduced strength of the grip and significant pain during exercise.

All patients underwent V-shaped corrective osteotomy of the MBs and plate osteosynthesis. Angular-stable mini-plates were used in three patients and low-profile plates without lockage were used in two patients. A comprehensive assessment of the treatment outcomes was carried out one year after surgery in all patients. The condition of the callus was assessed using standard hand radiography in two projections and computed tomography. The angular displacement of the MB was assessed using radiograms; the amount of active movements in the metacarpophalangeal joints and the force of the rough grip were also evaluated.

The intensity of pain was assessed using a visual analogue scale (VAS) and daily activity was evaluated according to the DASH questionnaire; the results were considered excellent, good, satisfactory and unsatisfactory according to the Buechler table (1996).¹² The frequency and nature of postoperative complications were also analyzed.¹³

The intervention according to our technique was performed under combined anesthesia, with a hemostyptic cuff on the shoulder. The technique was as follows. The patient's position – on the back with the arm drawn aside and a pronated forearm. The skin and subcutaneous tissue were cut with a longitudinal incision on the back of the hand in the projection of the deformed MB. The extensor tendons of the fingers and the dorsal digital nerves were moved aside and protected with elevators. The periosteum was cut longitudinally, the MB was exposed at the apex of deformation, somewhat proximal and distal from it. Through the apex of the MB deformation in the sagittal plane, a Kirchner wire was held. Towards this wire and at an angle of 35–45° to the vertical axis of the bone, a V-shaped osteotomy was performed subperiosteally, on the side of its proximal end with an oscillatory mini-saw.

During the dissection of the bone tissue, at the apex of the deformation angle, a bone bridge was maintained between the fragments up to 1 mm wide. Through the wire, located in the distal fragment, a plate with holes was placed. The distal end of the plate was fixed with a cortical screw to the distal fragment. Then the reposition was performed in combination with osteoclasia. At the same time, angular, rotational deformations and shortening of the metacarpal bone were eliminated (Fig. 1). The plate was fixed with a cortical screw to the proximal fragment of the MB, supplemented with lockable screws. Hemostasis was performed. The wound was sutured layer by layer.

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Fig. 1 Plan of operation: a ‒ holding the Kirchner wire (1) through the apex of deformation of the metacarpal bone (lateral view); b ‒ cutting at an angle α = 35–45° (2) to the vertical axis of the metacarpal bone (3) (top view); с ‒ elimination of the deformation of the metacarpal bone (lateral view).

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A temporary palm plaster splint was applied from the fingertips to the middle third of the forearm in the «intrinsic plus » position. From the first postoperative day, therapeutic gymnastics were performed for the joints of the hand and fingers. The daily load on the operated hand was allowed not earlier than three months after intervention.

3 Results and discussion

Changes in radiometric and functional parameters of the articular joints in the patients after intervention are presented in Table 1. The healing of the MB fragments occurred on average 10.5 weeks after surgery. The mean value of angular deformation decreased from 34.8° before intervention to 2.8° after it. The volume of active movements in the metacarpophalangeal joints increased from 64.8% to 85.5% of the healthy hand by this date. Rough grip strength increased from 52.5% to 113.9%. The mean pain intensity in the hand under load decreased from 3.4 to 0.4 points. The DASH questionnaire score, which reflect the quality of daily activities of the patients, improved on average from 37.12 to 4.94 points. Among complications, one case of tenodesis was recorded, which required a repeated intervention – removal of the metal structure and tenolysis of the extensor of the fifth finger. Metal fixators were removed in three patients during the period from 6 to 18 months after surgery, two of them – for social reasons. According to the Buechler table (1996),¹² the outcome was “excellent” in four patients and “good” in one patient.

Clinical example. Patient A., 16 years old, a high school student, was admitted to the traumatology department of the polyclinic in October 2015. Was injured five months ago, diagnosis: a closed fracture of the fifth MB of the right hand with displacement of fragments. In the emergency room a closed manual reposition was performed and a plaster splint was placed for four weeks. Subsequent conservative treatment was carried out in the clinic at the place of residence.

At admission, deformity of the right hand with retraction of the dorsal contour of the head of the fifth PC was noted (Fig. 2), the volume of active movements in the metacarpophalangeal joint was 66%, the strength of the rough grip of the hand was 54.6% compared to the contralateral limb. The patient evaluated pain in the hand under load as three points out of 10 on VAS.

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Fig. 2 The deformation of the right hand in the form of a depression of the back contour of the head of the fifth metacarpal bone before the operation.

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In the radiograms of the right hand, the healing of the fifth MB in the lower third was observed at an angle of 28° open to the palm and shortening of the MB by 4 mm (Fig. 3).

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Fig. 3 X-rays of the patient with posttraumatic deformation of the fifth metacarpal bone at an angle open to the palm of 28° and shortening by 4 mm.

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The intervention was performed according to the developed method (Fig. 4). The postoperative period was without complications. Immobilization was performed using a removable plaster splint only for the period of a night sleep. Active movements without load in the metacarpophalangeal and interphalangeal joints were initiated on the first day after intervention. Four weeks later, an outpatient course of restorative physiotherapy was used. Radiographic signs of MB healing in the osteotomy area were observed after eight weeks.

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Fig. 4 Procedure stages: a ‒ osteotomy at the apex of deformation, at an angle of 40° to the vertical axis of the metacarpal bone; b ‒ plate application; c ‒ elimination of deformation and final fixation of the plate; d ‒ intraoperative X-rays.

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At the control visit one year later: the deformation of the hand is completely resolved, the volume of active movements in the metacarpophalangeal joint was 100%, the strength of the rough grip of the hand was 190% compared to the intact limb (Fig. 5), there was no pain at rest and under load (0/10 on VAS). The results of the DASH questionnaire – 4.6 points.

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Fig. 5 Functional result after one year: a ‒ no hand deformation, the volume of active movements in the metacarpophalangeal joint ‒ 100%; b ‒ the strength of the rough grip of the hand – 190% compared to the intact limb.

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The computer tomogram and radiograms of the right hand showed the signs of complete healing of the metacarpal bone in the osteotomy area (Fig. 6). According to the Buechler table (1996),¹² the outcome was rated as “excellent”.

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Fig. 6 Results of CT scans and X-rays of the right hand one year after surgery: complete healing, complete elimination of the metacarpal bone deformation.

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The main goals of the treatment in malunited MB fractures are the elimination of deformations of the hand, restoration of a complete painless grip and maximum range of movements in the joints of the fingers. Currently, several types of corrective osteotomies of the MBs are used to eliminate their angular and rotational deformations.

In classical closing-wedge osteotomy, a v-shaped graft is resected at the apex of the deformation, fragments are repaired and osteosynthesis is performed. At the same time, due to the removal of the part of the MB, it is shortened. K. Karthik et al.⁶ used this method in 14 clinical observations and obtained improvements according to the results of the DASH questionnaire: from 57.54 baseline points – up to 5.95 points after intervention. The average MB deformation angle of 43° was completely eliminated. Despite some shortening, no additional MB lengthening interventions were required.

Pivot osteotomy proposed by A. Thurston et al. also belongs to the category of closing-wedge osteotomy.⁴ However, at the same time, MBs are resected only ½ of its diameter from the back side, which leads to a less significant shortening. In eight patients (10 MBs), the authors observed healing after six weeks. In one patient, due to a delayed consolidation, a relapse of the deformation was observed which required a revision surgery.

According to A. Bot and J. Jupiter,⁵ opening-wedge osteotomy in MB deformations, which requires a bone graft and stable fixation of the fragments with a plate and screws, results in the optimal restoration of the tendon tone and movement range in the hand joints.

X. Zhang et al.¹⁴ suggested that, when performing an opening-wedge v-shaped osteotomy of the MBs, the bone allograft should be placed on the palmar side of the post-repositioning defect for the prevention of the MB shortening.¹⁴ F. Yong et al.¹⁵ proposed a double osteotomy with the formation of a trapezoid graft at the apex of the deformation, which, after 180° rotation was placed between the proximal and distal fragments. The fragments and the graft were fixed with a straight mini-plate and cortical compression screws. Healing was observed on average after four months.¹⁵

The osteotomy we used was also opening-wedge. Its peculiarity was that MB healing in all clinical observations was achieved without the use of bone grafting. For the fixation of the MB fragments after osteotomy, various methods and constructions are used: Kirchner wires, intramedullary pins, mini-plates, external fixation devices, and cerclage wiring.

X. Zhang et al.¹⁴ performed the transfixation of the fourth and fifth MBs with the Kirchner wire for eight weeks after the opening-wedge osteotomy of the fifth MB.

I.A. El Delbani et al.⁹ used lockable metal intramedullary pins for MB osteosynthesis after osteotomy. The intervention was performed in 112 patients with malunited MBs. Healing was achieved over three to four months. The authors obtained good results in 97.2% of clinical observations.

In order to stabilize the bone fragments of the tubular bones of the hand and eliminate contractures in adjacent joints, V.I. Shevtsov et al.¹⁰ used a mini Ilizarov apparatus after the MB corrective osteotomy. Excellent and good treatment outcomes were obtained in 89.3% of clinical observations.

V.A. Kirsanov et al. proposed a combination of intramedullary and extrafocal transosseous osteosynthesis for the fixation of the fragments of the metacarpal bones after osteotomy, which allows the prevention of rotational displacements of the bone fragments, wire migration, deformation and fracture of the metal structure.¹⁶

According to D. Ring et al.,² complications, such as infection in the areas of surgery, delayed consolidation or non-union of the fragments, joint stiffness, degeneration, chronic pain, as well as destruction and migration of metal structures, may develop in corrective MB osteotomies.

According to our clinical observations, one patient developed stiffness in the metacarpophalangeal joint, requiring the removal of the metal structure and tenolysis of the fifth finger extensor in late postoperative period. There were no cases of non-union of bone fragments or fixator migration.

4 Conclusions

1.Opening-wedge V-shaped osteotomy of the metacarpal bones at the apex of their meta-diaphyseal deformation is an effective and safe technique for effective restoration of the coaxial alignment of the fragments and length of the segment.2.This technique does not require the collection of bone grafts from the donor area, therefore reducing the invasiveness of surgical intervention.3.Bone contact in the form of a bridge between MB fragments, maintained after osteotomy, provides a certain stability of the fragments, important for reposition and osteosynthesis, which contributes to uncomplicated healing.4.The use of stable osteosynthesis with angular-stable low-profile mini-plates provides early functional treatment of patients, which reduces stiffness in the joints of the fingers.

Source of funding

The study was conducted without sponsorship.

This study is limited to a small number and short duration of clinical observations. The example patient gave an informed consent to the publication of clinical data.