Multiple drill-hole osteotomy in hand surgery – description of a novel application and proof of feasibility

Metacarpal and phalangeal bone deformities pose dreaded complications when the bone fractures. The various potential deformities are termed rotational, flexion, extension, and impaction. These deformities result in functional deficits and aesthetic problems, in many cases [1, 2].

In reconstructive orthopedic surgery, the multiple drill-hole (MDH) osteotomy is an established technique for treating malpositions of large bones. MDH was previously described and utilized for corrective and lengthening osteotomies of the tibia, corrective osteotomies of the radius, and correction of the Madelung deformity [3, 4]. Compared to standard osteotomies performed with an oscillating saw, the advantages of MDH include reduced damage to the periosteal layer, the ability to perform the osteotomy percutaneously, higher precision with improved control, less potential for collateral damage to adjacent neurovascular structures, lower heat generation, no constraint on the course of the osteotomy and greater contact surface at the osteotomy site [4]. One study also reported improved bone consolidation after MDH osteotomy, compared to an osteotomy executed with an oscillating saw [5]. Alternatively, dentofacial surgeons utilize an ultrasound scalpel to perform osteotomies; this technique was recently adopted for hand surgery with satisfactory results. The features and potential advantages of that technique are similar to those of the MDH osteotomy, but it has the self-evident disadvantage of requiring equipment not commonly used in orthopedic surgeries [6, 7].

Corrective osteotomy in hand surgery represents a possible treatment option in patients with malpositioned metacarpals and phalangeal bones, but only data from small case series are currently available in the literature [1, 2, 8‐10]. Several osteotomy techniques have been proposed in past years, including transverse, oblique, open-wedge, closing wedge, pivot, and step-cut osteotomies. These techniques commonly utilize an oscillating saw to execute the osteotomy [1, 2, 8‐10]. However, oscillating saws are associated with several disadvantages, including potential damage to nerve and soft tissues, limited control of the osteotomy, and heat generation. The close proximity of anatomical structures around the metacarpals and phalanges intensifies these problems [6]. Therefore, we tested the MDH osteotomy technique for performing corrective osteotomies that targeted malpositions of metacarpal and phalangeal bones.

To our knowledge, the present study was the first to describe MDH osteotomies as a potential surgical treatment for malalignment of metacarpals and phalanges. This report aimed to provide proof of the feasibility of the MDH osteotomy for treating malpositions of phalanges or metacarpal bones in a case series of 11 patients.

This study was approved by the local ethics committee of the Medical University of Vienna. This retrospective observational study included 11 patients that underwent MDH osteotomies of metacarpals or phalanges. The present study did not affect clinical procedures. The local ethics committee of the Medical University of Vienna waived the need to obtain informed consent. Detailed patient and osteotomy characteristics are listed in Table 1.

In this case series, 11 patients (5 female, 6 male; mean age at the time of surgery: 31.5 years, range 18 to 60) received MDH osteotomies to correct malpositions of phalangeal or metacarpal bones (Table 1). The mean time between the initial injury and the correction osteotomy was 7 months (2–18 months). The mean operative time was 133.5 min (85–215). Indications for MDH osteotomy included malalignments after fractures (10 cases) and hand reduction surgery after amputation of the middle finger (1 case). The types of osteotomies were a derotational osteotomy, open-wedge osteotomy, closing-wedge osteotomy, modified scarf osteotomy, intra-articular osteotomy, and dome osteotomy. All planned osteotomies were technically feasible without complications, aside from the breakage of one drillbit (0.8 mm) during drilling (patient #9). The surgeon was able to remove the broken drillbit in total, and the osteotomy was completed as planned. In one case (patient #9), the entire extent of the planned osteotomy was not realizable, due to an underestimation of soft tissue contracture in the metacarpophalangeal joint. Nevertheless, a partial procedure provided a satisfactory result for the patient. We used both chisel and scalpel to complete osteotomies. These techniques were comparable, in terms of feasibility and outcome, with no complication. When possible, we preferred the use of a scalpel, because it provided more control in completing the osteotomy.

In this case series, all osteotomies healed with a mean time of 6 weeks, between surgery and radiologically visible bone consolidation, defined as an undetectable fracture cleft. We did not observe any surgery-related, post-operative complication. All patients reported satisfactory results at the final examination.

With this case series, we provided the first evidence that MDH osteotomies were feasible and safe in corrective surgery for phalangeal and metacarpal bones. Despite the small number of patients treated in this study, we are confident that our findings provide additional information and treatment options to surgeons treating cases of phalangeal and metacarpal malpositions.

In general, corrective osteotomies of phalangeal or metacarpal bones represent a rare indication in hand surgery. These procedures require a high degree of individual planning, due to the broad spectrum of malalignments and various treatment options. Taken together, these characteristics require a variety of surgical techniques, which are adopted from reconstructive orthopedic surgery [1, 2, 4, 8‐10]. Previous studies showed that the MDH osteotomy technique provided several advantages over osteotomies performed with oscillating saws. In studies on reconstructive surgery of the “long bones”, the MDH technique minimized the surgical approach and reduced heat generation typically incurred with saws to optimize callus distraction. We found that, in hand surgery, MDH provided the advantages of higher precision and control during the osteotomy [6, 7, 12]. This feature was particularly important in hand surgery, which involves delicate anatomical structures in close proximity; additionally, well-orchestrated hand movements demand anatomically aligned metacarpal and phalangeal bones with small tolerance margins. Therefore, in this region, osteotomies require exact planning and execution, high precision, and strict control. In addition, the greater control of MDH increased the safety of the procedure by limiting damage to surrounding neurovascular structures. Another alternative to oscillating saws is the chisel for performing osteotomies. However, using a chisel alone for osteotomies has clear disadvantages, compared to the MDH method, including the unpredictability of the extent of osteotomy; the risk of incurring adjacent fractures; the risk of mechanical damage to tendons, ligaments, and neurovascular structures; the risk of causing bone defects at the osteotomy site; and its impracticability for performing intra-articular osteotomies. Finally, the MDH technique makes other osteotomy types possible; for instance, osteotomies that do not require bone modifications, like autologous bone transplantation or bone shortening.

Using drilling to perform osteotomies adds indentations to both planes of the osteotomy, and it increases the contact surface area, which can potentially improve initial stability. Both these features are prerequisites of enhanced bone healing [4]. We experienced subjective locking-in of both osteotomy borders due to the profile created by the multiple drill-holes, when we brought them together after correcting the malalignment. This feature provided improved control over temporary fixation prior to osteosynthesis. Sparing the periosteum requires high healing capacity at the osteotomy site. The MDH technique promotes healing by reducing the heat production and increasing the contact surface area, which is achieved with the indentions that naturally occur during drilling. Furthermore, compared to oscillating saws, the drill permits osteotomies with variable courses and angles; for example, the dome osteotomy performed in patient #3. In this case, the alternatives included a standard closing-wedge osteotomy, which would have significantly shortened the thumb, or an open-wedge osteotomy, which required the transfer of an iliac crest autograft in the diaphyseal bone. Also, compared to oscillating saws, drills cause less severe bone defects, which are inherent in the execution of all osteotomies. The reduced bone loss incurred with the MDH technique facilitated the execution of intra-articular osteotomies, as performed in patients #2 and #4. In these cases, the alternative would have been a hemi-hamate arthroplasty, which is associated with morbidity at the extraction site [13].

We suggest that there are two reasons why MDH osteotomies have not prevailed in patients suffering from metacarpal or phalangeal malunion has three reasons: 1) Orthopedic surgeons are accustomed to the use of saws for osteotomies in general, 2) Correction of metacarpal or phalangeal malunions is a rare indication, which results in reduced willingness to apply different techniques, 3) the use of a saw for osteotomy is easier in terms of technical feasibility and quicker. Even more so, the present study adds important knowledge to the field of corrective osteotomy for phalangeal and metacarpal malunion.

In general, a non-union represents a potential complication in osteotomies [14, 15]. The current literature demonstrates that the technique used in ulnar-shortening osteotomies was correlated with the complication rate. One study showed that oblique osteotomies were associated with lower non-union rates. Those authors claimed that increasing the contact surface at the osteotomy site resulted in improved healing rates [14, 16‐18]. Heat generation during osteotomy is thought to be associated with reduced healing capacity [14, 19]. Inherently, MDH osteotomies both reduce the heat generation and increase the contact area. In our opinion, these features were involved in the satisfactory results and appropriate bone healing achieved in the present case series (Fig. 3). Only in one case (patient #5), we observed a prolonged period of bone consolidation of 12 weeks. In this case, a combination of dome- and open-wedge osteotomy was necessary to correct the underlying malposition. To avoid shortening, a remaining bone-gap after osteosynthesis was required leading to longer time to consolidate in this case. Still, to our opinion bone healing was achieved in an adequate timeframe comparable to other techniques. Recent studies have shown that, aside from the rotational speed and the feeding rate (i.e. forward momentum of the drill within the bone), the drillbit diameter is a key factor associated with heat production during drilling [20, 21]. In one study, critical heat production was reported with drillbits that were 4.5 mm in diameter, and drilling with smaller diameter drillbits did not lead to critical heat production [21]. In the present study, we used drillbits up to 1.2 mm in diameter. Augustin et al. reported a maximum temperature of 41.5 °C when drilling with a 2.5-mm drillbit, which is well below the critical temperature (47 °C) for thermal osteonecrosis [21, 22]. Those authors also showed that the drill angle was not relevant for heat production during drilling. Those findings supported our findings, and underlined the advantages of using MDH osteotomy in hand surgery. Also, we only experienced surgery-associated complication in one case of drillbit breakage (patient #9) using a drillbit of 0.8 mm in diameter. In this case, we were able to remove the broken drillbit easily. To avoid this complication, cautious drilling is important especially when using small diameter drillbits. The osteotomy site needs to be dissected meticulously to avoid drillbit deflection by soft tissue, which is associated with increased risk of drillbit breakage.

Short time intervals between surgery and bone consolidation make it possible to implement early active postoperative therapy protocols, which are associated with earlier returns to work. Based on our experience with osteotomies, achieving radiologically visible bone consolidation within a mean of 6 weeks is a comparatively short healing time for osteotomies, in general. This healing time was comparable to that found in current studies on MDH and to that observed in naturally occurring bone consolidiation [23, 24].

Recently, patient-specific instruments and drill guides were described for treating complex malunions of the distal radius with MDH ostetomy [24, 25]. Further development of this and similar techniques, including patient-specific drill sleeves, screws, and plates, might be applicable to hand surgery in the near future; moreover, these developments might lead to individualized osteotomies.

This small, retrospective case series had some limitations. We could not provide proof that MDH osteotomies were superior to osteotomies performed with oscillating saws, due to the study design. Future prospective clinical trials would be required to address this question. However, given the small patient numbers, in general, and the number of cases that require specific individual treatment strategies, it is unlikely that such prospective clinical trials will be feasible. Fortunately, the present case series includes important information for surgeons that treat these rare cases of phalangeal and metacarpal malalignment.

The present observational case series study demonstrated the feasibility and safety of using MDH for correction osteotomies in hand surgery. Our results suggested that MDH osteotomy represented an attractive alternative to standard procedures with oscillating saws or a chisel alone for correction osteotomies of phalangeal and metacarpal bones. In particular, for complex cases, in our opinion, the MDH method can extend the spectrum of potential surgical procedures.