Is minimally invasive application by intramedullary osteosynthesis in comparison with volar plating real benefi t in the treatment of distal radius fractures ?

Purpose of the study: Can minimally invasive intramedullary osteosynthesis of distal radius fractures provide better therapeutic results than multidirectional locking plates. Retrospective study of  patients operated for distal radius fractures,  were treated with intramedullary X-screw (XSCR) fi xation and  with the multidirectional angle-stable plate system (APTUS). Th e evaluation at -year follow-up included functional status of the wrist and hand, and radiographic fi ndings. In the XSCR group, the functional outcomes of the treated extremity did not achieve values comparable with those of the uninjured side in any of the parameters measured. Th e radiographic fi ndings did not meet the requirements of successful healing due to failure to restore an anatomical volar tilt in . cases. In the APTUS group, comparable values of the injured and the uninjured side were achieved in radial deviation, ulnar deviation, pronation, supination and grip strength. Th e radiographic criteria of successful healing were met by all fractures treated by locking plate osteosynthesis. Implant migration associated with secondary displacement of bone fragments was recorded in .  of the XSCR patients and only in .  of the APTUS patients. Th e overall evaluation show that intramedullary osteosynthesis does not produce better treatment outcomes compared with plate osteosynthesis in indicated types of fractures. ©  Association of Basic Medical Sciences of FB&H. All rights reserved


INTRODUCTION
Fractures of the distal radius are complex injuries with varied prognosis depending on the type of fracture and method of treatment [].Th ere is still no clinical evidence suggesting a superior modality for their management [].The current therapy most frequently involves open reduction and plate osteosynthesis [].Angle-stable fixation provides sufficient stability of the fracture to allow early start of rehabilitation soon after surgery; consequently, the total treatment time is shorter and good functional outcomes are achieved even in unstable grossly comminuted intra-articular fractures [, ].Application of a volar plate with angle-stable fixation has been used successfully in a number of cohort studies but needs to be examined in stringent trials to determine if there is any ben-efit when compared with other treatment modalities [].Intramedullary osteosynthesis is used for fragment fixation less frequently and good radiographic and functional outcomes have been published [].However, its range of indications limited to the management of extra-articular and simple intra-articular fractures is a disadvantage of the method [].Only a few clinical evaluations are available.Lerch et al. [] in an isolated study on a small patient group report comparable results for plate and intramedullary osteosyntheses (Targon DR, Aesculap Implant Systems, Center Valley, PA, U.S.A.) and relate the excellent functional scores for nailing to the minimally invasive procedure.Ilyas et al. [] have reported that using the intramedullary nail (Micronail, Wright Medical Technologies, Arlington, TN, U.S.A.) in the treatment of displaced distal radius fractures can result in good functional outcome, but is associated with a high incidence of complications, i.e., screw penetration into the distal radioulnar joint,  and transient superfi cial radial sensory neuritis,  .No studies evaluating the results of X-screw (Zimmer, Inc., Warsaw, IN, U.S.A.) intramedullary osteosynthesis have been published so far.Since  for surgical stabilization to all types of distal radius fractures multidirectional angle-stable plates applied from volar approach are used in our practise.In  we have also started to use X-screw implant allowing intramedullary osteosynthesis.In a retrospective study, we decided to elucidate whether this minimally invasive implant can provide comparably good therapeutic results as multidirectional locking plates.

MATERIALS AND METHODS
Th erapeutic approaches at our department Patients with non-displaced fractures of the distal radius referred to the Trauma Center at the Teaching Hospital in Motol are indicated for conservative treatment.Th ose with displaced fractures receive urgent treatment at the in-patient and emergency department of the center, involving reduction of the fracture under local anesthesia ( ml   Mesocaine injected into the fracture site) and immobilization of the extremity with a dorsal and a volar plaster splint.Based on plain postero-anterior and lateral radiographs taken after reduction, the patients are indicated for further treatment.Patients who failed to achieve anatomical reduction that meets the criteria for successful treatment [] are then indicated for surgical treatment either by intramedullary or plate osteosynthesis.

Patient groups
Between February  and November , a total of  fractures of the distal radius were treated at our department, and of this number were  fractures surgically solved.Of the patients treated,  came to the final examination and evaluation of outcomes at a follow-up of  months although all patients operated on by the fi rst author in the period mentioned above had been invited.All patients were adults with an uninjured contralateral extremity, who underwent surgery within  days of injury.Th e indication criteria for treatment of distal radius fractures by intramedullary X-screw osteosynthesis included an absence of osteopenia on plain X-ray and the patient's preference for a minimally invasive procedure.Th e remaining patients were treated by open reduction and internal fi xation (ORIF) using volar locking plates with variable-angle screw insertion.Indications for surgery were based on antero-posterior and lateral radiographs; when a fracture was more complicated, CT examination was carried out.Fracture types were assessed according to the AO classifi cation system [].Patients with pseudoarthrosis, pathological fractures, refractures, open fractures, multiple factures of the ipsilateral extremity and fractures associated with multiple injuries were excluded.
The XSCR group of patients with distal radius fractures treated by intramedullary X-screw osteosynthesis (Zimmer, Inc., Warsaw, Indiana, U.S.A.) comprised  patients with a mean age of . years (range,  to ; SD, .) (Figure ).A Th e mean injury-surgery interval was  days (range,  to ; SD, .).Four patients had distal radius fractures without joint involvement and  had fractures with intra-articular injury.Th e fractures were due to falling after a stumble while walking (.

Operative techniques
All patients were operated on with intravenous infusion of a second generation cephalosporin antibiotic before a tourniquet was applied.Th e X-screw is a form of intramedullary osteosynthesis of the distal radius based on combination of a special screw with threaded Kirschner wires.A -mm incision was made on the radial side over the radial styloid process.After reduction, the fracture was temporarily fi xed with a Kirschner wire.A cannulated screw was inserted over the wire and tightened to further compress the fragments and hold the reduction.Once the screw was anchored, no further correction of fracture position was possible.Osteosynthesis was completed with an adequate number of wires inserted by aimer device from small incisions.The wrist was immobilized with a dorsal plaster splint for  weeks in type A3 fractures and for  weeks in type C fractures.Type A2 fractures were not immobilized.Supervised rehabilitation of the hand and wrist started at  post-operative weeks.Th e multidirectional angle-stable plates Aptus radius were applied from the flexor capri radialis (FCR) approach as follows: access to the radius was gained between the radial vascular bundle and the FCR tendon.The pronator quadratus muscle was dissected from the anterior surface of the radius, shifted medially in a fl ap and secured with a hook.Fluoroscopy-guided reduction of the fracture was performed and fragments were temporarily fixed with Kirschner wires.Subsequently, the plate itself was applied.The extremity was immobilized in a brace.In less serious cases, supervised rehabilitation was started at  weeks and, in more complex fractures, at  weeks post-operatively.

Follow-up examination
Clinical fi ndings were evaluated immediately after surgery and then at , ,  and  weeks and ,  and  months of follow-up.Radiographs were obtained within the visits at  and  weeks and ,  and  months.Th e clinical outcome was evaluated using international scores at one-year follow-up.Th e range of wrist motion (volar fl exion, dorsal fl exion, radial deviation, ulnar deviation, supination and pronation) was measured with a goniometer and grip strength was assessed with a hand dynamometer (Vigorimeter, Martin, Tuttlingen, Germany).Th e values were compared with those obtained for the uninjured side.We were aware of diff erent muscle strength between the dominant and non-dominant hand but, because of a signifi cant similarity of this characteristic in both groups (p=.), this was not taken into consideration.Antero-posterior and lateral radiographs were examined for radial height, radial inclination, ulnar variance, volar tilt and articular surface step-off.The findings were compared with the standard anatomy of the distal radius to avoid X-ray exposure in the contralateral wrist.The values of radial height, radial inclination, ulnar variance and volar tilt in lateral projection described by Ruedi et al. [] were taken as the standard anatomical parameters.In all patients the results were evaluated using the scoring systems of Gartland and Werley [], Castaing [] and the Disability of the Arm, Shoulder and Hand (DASH) questionnaire [].

Statistical analysis
The data obtained were statistically evaluated (ttest and chi-square test) at the . level of significance using Statistica  (StatSoft, Incorporation, Tulsa, Oklahoma, U.S.A.) and SPSS Statistics  (SPSS Incorporation, Chicago, Illinois, U.S.A.) software programs.

Functional outcomes
In  the XSCR group, only the volar tilt was fully restored.Th e other parameters were significantly different from the anatomical standards.The radiographic findings did not meet the criteria for successful treatment [] in four patients (.), of whom one had an insufficient radial height and three had no satisfactory radial inclination.
In the APTUS group, all fractures were completely healed but only the radial height was comparable with the anatomical standard; the other parameters were signifi cantly diff erent (p<.)(Table ).However, the criteria of a successful outcome [], were fulfilled in all fractures in this group.thumb extensor tendon caused by the tip of a screw projecting through the dorsal cortex of the radius.Th is was managed by hardware removal and transfer of the extensor indicis proprius tendon onto the distal part of extensor pollicis tendon.

Scores
Complex regional pain syndrome developed in two XSCR (.) and three APTUS (.) patients.Treatment with intranasal calcitonin application and increased calcium intake resulted in subsidence of clinical and radiographic findings in  months.The complications and their management are shown in Table .

DISCUSSION
Restoration of the normal anatomy as a prerequisite for good wrist and hand function is currently taken as an imperative in the management of distal radius fractures.However, in unstable fractures refractory to conservative treatment there is still no clear evidence suggesting which method of osteosynthesis should be indicated for each of the fracture types.Th e functional outcomes of intramedullary osteosynthesis of the distal radius generally have very good scores, chiefl y due to minimal invasiveness of the methods used [].With the intramedullary nail Targon DR, the resulting values for the range of wrist motion in all directions and for grip strength reached  to  of those measured on the uninjured side [].However, our XSCR patients achieved the  level only in pronation.Th e least satisfactory range of motion (ROM) was in ulnar deviation (. of the healthy wrist value).Failure in direct relation with restoring ulnar deviation has to be considered radiographic results and inability to restore radial length (mean ulnar variance of . mm).Diffi culties in anatomical restoration of normal volar tilt ( degrees) with the use of nailing techniques have been published.In a study comprising  patients, Gradl et al. [] reported achieving only a mean volar tilt of . degrees.Th e mean value of . degrees for volar tilt in our XSCR patients can be regarded as a very good result testifying for good stability of the X-screw implant in terms of radiographic parameter.On the other hand, radial height and radial inclination were not fully restored in these patients.However, problems with maintaining volar tilt while achieving good restoration of the other radiographic parameters have also been described for the Micronail [].Th e Castaing scores showed excellent and good results in . , and the Gartland-Werley scores were excellent and good in . of the XSCR patients.Worse results with the Castaing scoring system were due to relative lengthening of the ulna.
In the XSCR group, the most serious complication included loss of correction in . of the patients.Th is value is extremely high compared to the .  of the patients treated by plate osteosynthesis.Secondary displacement in the XSCR group was always associated with grossly comminuted fractures (A3, C3 and C2).Th is result should be taken into consideration when indicating complex fractures of the distal radius for intramedullary osteosynthesis.Kirschner wire migration did not prove a serious complication because it occurred after complete fracture union and was not associated with secondary fragment displacement.Paresthesia in the region innervated by a sensitive branch of the radial nerve resolved spontaneously.In the future this can be avoided by a careful operative technique involving good intra-operative visualization of the nerve.Th e absence of any injury to tendons is a great advantage of the intramedullary technique.
Our experience with intramedullary osteosynthesis, as well as conclusions of other authors [, ] have shown that the major advantage of this technique is its good functional outcome.A full range of wrist motion at  post-operative months with use of a Micronail® implant has been described.Th is advantage is in contrasted to high complication rate and a narrow indication range regarding to AO fracture types [].
In the APTUS group, the range of motion achieved in radial and ulnar deviation and in pronation and supination was comparable with that of the uninjured side; however, the values for both volar and dorsal fl exion were markedly lower.A restricted ROM of only  to   of that at the uninjured wrist has repeatedly been reported at -year follow-up in patients treated by the volar locking plate system [, ].However, the hand/wrist functional status recorded at  year need not be fi nal and may further improve.A previous study has shown that patients achieve most of their improvement in wrist motion range and grip strength by  months, but they may continue to improve up to around  months [].
The functional outcomes assessed using the Gartland-Werley scores were excellent and good in . of the AP-TUS patients.Th is is in agreement with the results reported by Osada et al. [] in  displaced intra-articular fractures treated with a volar locking plate system.Good functional  outcomes in the treatment of distal radius fractures using plate osteosynthesis are achieved in spite of a high incidence of complications [].Based on the criteria for successful treatment [], our results are excellent and are similar to those described by other authors for the treatment of distal radius fractures with volar locking plates [, ].
In one APTUS patient, injury to the extensor pollicis longus tendon was caused by a screw penetrating through the dorsal corticalis.It was managed by implant removal and repair of the rupture with tendon transfer.Th is damage can be avoided by a careful operative technique with use of fl uoroscopic guidance during screw insertion to prevent penetration of a screw through the dorsal corticalis of the distal radius.The loss of correction was the most serious complication.Two APTUS patients (. ), women with osteopenia aged  and  years, experienced secondary displacement of type A3 and type C3 fractures, respectively.Revision surgery was not indicated; no patient wanted to have the implant removed.Koenig et al. performed a study to evaluate whether early internal fi xation or non-operative treatment is preferred for displaced, potentially unstable distal radial fractures with initial adequate reduction.They found that internal fi xation with a volar plate provided a higher probability of painless union for potentially unstable distal radius fractures.However, patients older than  years, who had lower risk of symptomatic malunion seemed to prefer nonoperative treatment [].Our results of the APTUS group confirm this statement.Because due to poor bone quality even angle-stable plate does not suffi ciently guarantees good stability for all bone fragments.On the other hand, the risk of fracture re-displacement in a plaster cast is higher in osteoporotic bone compared to healthy bone.Clayton et al. [] identifi ed a high correlation between bone mineral density and the severity of distal radius fractures.Th ey found that the probability of early instability was   in osteopenic patients and only   in those with normal bone mineral density.But other authors reported on high stability of locking plate osteosynthesis for osteoporotic bone fractures [].Th e evaluation of our groups based on the scoring systems for the assessment of wrist functional state, both objective and subjective, as well as clinical and radiographic findings showed that the results achieved with either locking plates or intramedullary osteosynthesis were comparable and generally good.In terms of objective evaluation, the patients with locking plate osteosynthesis had a better ROM, i.e., the range was closer to that of the contralateral wrist, than the patients with intramedullary osteosynthesis.Radiographs demonstrated good restoration of radial height in the APTUS group and maintenance of adequate volar tilt in the XSCR group.Regarding complications, there was a high incidence of secondary loss of correction and im-plant migration in the XSCR group.Overall assessment it must be taken into consideration that the APTUS group included a signifi cantly higher number of younger patients.

CONCLUSION
The overall evaluation based on the conventional scoring systems show that intramedullary osteosynthesis does not produce better treatment outcomes compared with plate osteosynthesis in indicated types of fractures.
Our study showed that the minimally invasive application of intramedullary osteosynthesis in treatment of the distal radius fractures is only a relative advantage over surgical stabilisation using multidirectional locking plates.
In intramedullary techniques good anatomical reduction and its maintenance while the implant is being inserted, is often difficult to achieve from through small incision without a direct visualisation of the fracture.
Intramedullary techniques are also associated with frequent secondary displacement of bone fragments and implant migration.

DECLARATION OF INTEREST
Th e authors declare no confl ict of interest.
Bosn J Basic Med Sci 2014; 14 (2): 82-88 MARTIN VLČEK ET AL.: IS MINIMALLY INVASIVE APPLICATION BY INTRAMEDULLARY OSTEOSYNTHESIS IN COMPARISON WITH VOLAR PLATING REAL BENEFIT IN THE TREATMENT OF DISTAL RADIUS FRACTURES?

FIGURE 1 .
FIGURE 1.A type A3 fracture of the distal radius.Postero-anterior and lateral radiographs of the fracture (patient B.N.) A) after injury; B) at 3 months after intramedullary X-screw fi xation.

FIGURE 2 .
FIGURE 2. A type C1 fracture of the distal radius.Postero-anterior and lateral radiographs of the fracture (patient V.H.) A) after injury; B) at 3 months after Aptus radius locking plate fi xation.
Th e XSCR group showed .  excellent and good results on the Castaing scoring system and .  on the Gartland-Werley score.The average DASH score was . points.In the APTUS group, excellent and good results were achieved in .  and .  of the patients assessed using the Castaing and Gartland-Werley scores, respectively.The average DASH score was . points.The results are presented in

FIGURE 3 .
FIGURE 3. Functional outcome evaluation using the Castaing score.

Table  .
 ) or were sustained in sports activities (. ).Lower number of fractures treated by intramedullary method compared to group of plate osteosynthesis was given a narrower indication extent of X-screw implant.
days (range  to ; SD, .).Nine fractures were without and  with joint involvement.Th ey were due to falling after a stumble (. ) or were sustained in association with sports activities (. ) or in motor car accidents (. ).Both the XSCR and APTUS groups were matched as for gender, injured body side and AO fracture type, but diff ered B 
A B  Bosn J Basic Med Sci 2014; 14 (2): 84-88 MARTIN VLČEK ET AL.: IS MINIMALLY INVASIVE APPLICATION BY INTRAMEDULLARY OSTEOSYNTHESIS IN COMPARISON WITH VOLAR PLATING REAL BENEFIT IN THE TREATMENT OF DISTAL RADIUS FRACTURES?
fi ndingsRadiographs obtained at a one-year follow-up showed complete bony union in all fractures of both groups.In

TABLE 2 .
Functional ranges of motion of the wrist joint and grip strength.
* Parameters with corresponding values of both extremities * Parameters with corresponding values of both extremities

TABLE 4 .
Table  and Figures  and .Scoring systems.
* Parameters with corresponding values of both extremities

TABLE 5 .
Complications and their management.MARTIN VLČEK ET AL.: IS MINIMALLY INVASIVE APPLICATION BY INTRAMEDULLARY OSTEOSYNTHESIS IN COMPARISON WITH VOLAR PLATING REAL BENEFIT IN THE TREATMENT OF DISTAL RADIUS FRACTURES?