Minimally Invasive Plating of Distal Radius Fracture: A Series of 42 Cases and Review of Current Literature

Surgical techniques developed for distal radius fracture fixation have become increasingly advanced, including minimally invasive plate osteosynthesis (MIPO). This study aimed to introduce and evaluate the functional outcome of a novel MIPO technique that differs from previous reports. This study included 42 patients with distal radius fractures who underwent minimally invasive surgical plating of the distal radius. All patients were treated with closed reduction, fixation using K-wire, and subsequent insertion of a volar anatomical stable angle short plate on the distal radius. An arthroscopy-assisted evaluation and repair procedure were performed to correct intra-articular involvement, triangular fibrocartilage complex tears, and scapholunate injuries. Functional outcomes were assessed using a visual analog scale score; quick disabilities of the arm, shoulder, and hand score; and postoperative range of motion of flexion, extension, supination, and pronation at the 3-month follow-up, showing significant improvement in all parameters (all p ≤ 0.05). This study provides a simpler yet reliable method with reproducible and consistent results to treat distal radius fractures using minimally invasive plating with closed reduction and plate insertion, resulting in satisfactory clinical outcomes in all patients.


Introduction
Distal radius fractures have been recognized as the most evolving treatment with a signifcant milestone. Tey are one of the most common orthopedic injuries, accounting for 8%-15% of all bone injuries found in the adult and elderly population. Teir occurrence in humans has been recorded as early as 5000 years ago in an ancient Egyptian case report within the Edwin Smith Papyrus [1]. Before the invention of röentgenography, Pouteau (1783), Colles (1814), and Dupuytren (1847) described distal radius fractures and how to reduce them, including the importance of immobilization. While further discussion regarding the degree of displacement and articular involvement has become an emerging issue since the invention of roentgenography, treatment was still nonoperative using casts or traction [1,2].
Operative treatment was reported for the frst time in 1908 when Lambotte operated on a distal radius fracture using percutaneous K-wires through radial styloid to maintain reduction. However, intraarticular comminution still became a signifcant issue. Anderson and O'Neil addressed this issue using the ligamentotaxis concept with a joint-spanning external fxator. A signifcant advancement was made when a group of Swiss surgeons met to discuss fracture management, known as Arbeitsgemeinschaft für Osteosynthesefragen (AO). Shortly afterward, two case reports were published due to growing interest in operative management of distal radius fractures. Since then, the operative treatment of distal radius fractures has grown rapidly, including volar and dorsal plating, distraction plating, intramedullary implants, and the arthroscopic approach [1,2]. While operative approaches have been used for complex distal radius fractures, there are potential complications, including loss of fxation, refex sympathetic dystrophy, neuritis, and wound infection. Minimally invasive plate osteosynthesis (MIPO) of a distal radius fracture ofers a solution to overcome these complications [3,4].
Recent literature regarding the MIPO approach for distal radius fractures has been reported by Liverneaux [5] aiming to overcome potential complications from open surgery. MIPO aims to decrease skin incisions and preserve the periosteum and pronator quadratus. Preservation of the associated anatomical parts may favor bone healing. In addition, a minimally invasive approach would increase patient satisfaction with a pleasant cosmetic appearance. Tis case series reports a novel minimally invasive technique, including closed reduction and smaller plate insertion, and its outcome.

Patient Selection.
Tis study included 42 patients with distal radius fractures who underwent minimally invasive surgery plating of the distal radius between January 2021 and December 2021. Tis study was approved by our institution's Ethics Committee (approval number: UM.01.05/VIII.5/412/ 2022), and informed consent was obtained from all patients. We included patients with AO/Orthopaedic Trauma Association type A2, A3, or B3 distal radial fractures for MIPO. Type A2 was an extra-articular radius fracture with an impacted fragment. Type A3 was an extraarticular radius fracture involving multiple fragments. Type B3 was a partial articular radius fracture, with the primary fracture in the coronal plane involving the palmar rim.

Operative
Procedure. Te operating procedure was adopted from Livernaux [5] with simplifying modifcations. All patients were operated on under general anesthesia using the same techniques by a single surgeon (OS). An "ExtremiLock ™ wrist short narrow plate (Osteomed, USA) was used in this series. Technically, "ExtremiLock ™ is easier to use due to its smaller and shorter size. Te patient was positioned supine with the afected arm on a Mayo table. Various techniques were performed closed to achieve acceptable reduction under an image intensifer. Tis step was essential because the fracture's reducibility determined the next step. Figure 1 shows various techniques in closed reduction. After achieving an acceptable reduction, one or two 1.4 mm Kirschner wires were introduced obliquely from the radius styloid process to the proximal ulnar side as a provisional fxation. Ten, a 1.5 cm incision was made using the fexor carpi radialis (FCR) approach, 2 cm proximal to the tip of the radial styloid. Te fexor carpi radialis sheath was also dissected longitudinally to the same extent. Except for the radial artery, all tendons, muscles, and nerve structures were ulnarly retracted until the pronator quadratus was exposed. A specialized periosteal elevator was used to elevate the pronator quadratus proximally to create space for the site of the plate. Ten, the plate was inserted beneath the elevated pronator quadratus over the reduced fracture, and fxation was completed using locking screws. Care should be taken to not violate the radiocarpal joint using fuoroscopy guidance. Te operative procedure is shown in Figures 1 and 2.
Outcomes were assessed by comparing preoperative and postoperative evaluations. Postoperative follow-up included pain measurement on the visual analog scale (VAS) from 0 (no pain) to 10 (maximum pain imaginable). Global hand function was evaluated using the quick disabilities of the arm, shoulder, and hand (DASH) score from 0 (normal upper limb function). Wrist mobility was measured in fexion, extension, pronation, and supination. Radiological criteria included volar tilt, radial inclinations, and ulnar variance.

Statistical Analysis.
Univariate analyses were performed to describe the data distribution and measure the mean and standard deviation of symmetric distributions and the median and interquartile range of asymmetric distributions. Bivariate analyses using paired t-tests for symmetric and Wilcoxon signed-rank tests for asymmetric distributions were used to determine the relationship between each variable. All results with p ≤ 0.05 were considered statistically signifcant. Te collected data were analyzed using the SPSS v.26 software. Te same study authors performed all statistical analyses.

Subject Characteristics.
Tis study included 42 patients with distal radius fractures who underwent minimally invasive surgery, of which 24 were male (57.1%) and 18 were female (42.9%) with a mean age of 41.14 years (range 21-65). Te patients' demographic, clinical, and radiological data are shown in Table 1.
All patients underwent a minimally invasive approach using closed reduction and plate and screw fxation. Arthroscopy was performed in six patients with intraarticular involvement. Detailed information on each patient's fracture is provided in Table 2. Teir postoperative six-week followup is shown in Figures 3 and 4. Two patients reported early complications, such as stifness and wound breakdown. However, the complications resolved on their own.

Postoperative Outcomes.
We found signifcant diferences in VAS score, functional outcome, and range of motion (ROM) between postoperative and three-month follow-ups (Table 3). Clinical examination of the patients at their three-month follow-up is shown in Figure 3.

Discussion
Our study aimed to evaluate a minimally invasive technique that includes closed reduction and plate insertion in patients with distal radius fractures. It included 42 patients with a mean age of 41.14 years (range 21-65). A large epidemiological study by Azad et al. examining 1,124,060 distal radius fractures showed that they occurred most frequently in the pediatric (10-14 years) and elderly (>65 years) populations. Te contrasting ages of our patients refect our study's much smaller cohort [6]. However, previous distal radius reports specifcally discuss MIPO's relatively similar demographic population [4,7,8].
Te variation in fracture type was also present in our patients. In addition, some also had associated lesions, such as triangular fbrocartilage complex (TFCC) tears and scapholunate injuries. A previous study by Wei et al. included diferent fracture classifcations, including type A2, A3, B1, B3, C1, and C2. Tis variation is important because heterogenous subjects may afect the study outcome. However, we performed various reduction techniques to overcome such variation and obtain optimal articular congruency in all cases. Associated injuries, including TFCC tears and intraarticular involvement, were treated using arthroscopy-assisted TFCC repair. Tis arthroscopy-assisted procedure in MIPO of the intraarticular distal radius is required to resolve intraarticular congruency and associated intraarticular injury and has been performed in many previous reports [4,7].
Several previous reports have been published on conventional and minimally invasive techniques for distal radius fractures [9,10]. Te conventional technique requires an incision in the skin and pronator quadratus muscle with a further detachment of the periosteum in the fracture area. Te MIPO technique was proposed due to its better fracture healing and cosmetic outcomes. In addition, a minimally invasive technique generally preserves blood supply adjacent to the pronator quadratus muscle, resulting in less muscular damage.
Swiontkowski et al. [9] compared conventional and MIPO techniques, using brachial plexus block as the primary MIPO anesthesia. Lebailly et al. [7] also used regional anesthesia in all distal radius fracture patients treated with a minimally invasive technique. Peripheral nerve blocks such as brachial plexus have been associated with reduced opioid doses and shorter hospital stays. Terefore, they are frequently used in upper extremity surgeries, such as those for distal radius fractures [11].
However, our study used general anesthesia. Romero Prieto et al. [12] previously reported using general anesthesia to treat distal radius fractures. General anesthesia may be suitable for patients with anxiety, long surgery duration, or contraindications for regional anesthesia. General anesthesia is also safe and economical despite several potential drawbacks compared to peripheral nerve block [11].
Te MIPO procedure proposed by Swiontkowski et al. [9] was similar to ours, involving closed reduction with subsequent intrafocal pinning with the Kapandji technique. Te incision was made transversely along the transverse wrist skin crease. Zemirline et al. also used external manipulation for reduction with fxation using K-wires. However, they also used arthroscopy for high-energy trauma or intraarticular involvement. Despite the same incisional approach in both studies, Zenke et al. used a longer single transverse incision (3 cm vs. 1.5 cm). Both studies showed no signifcant diference in overall outcomes between conventional and MIPO procedures [8]. Tis result was also supported by our fndings, where an average 1.5 cm transverse incision was sufcient without complications such as secondary displacement postoperatively and after follow-up.
Te shorter incision is reasonable while using a smaller plate for fxation. In contrast, Pire et al. [10] used Henry's approach, which uses a 15 mm proximal longitudinal incision to the radial styloid apex. Tey used a long volar plate under the pronator quadratus. Tey reported better cosmetic and economic advantages with MIPO compared to the conventional procedure, also without signifcant diferences in clinical outcomes [10]. Wei et al. also used a longitudinal incision, although they used two rather than one. Tey also reported overall satisfactory clinical outcomes in their patients [4]. Teir rationale for using a longitudinal incision was to allow sufcient access to the radial epiphysis and better cosmetic results than a transversal incision.
Transverse incisions have been reported to be bothersome for patients, usually misinterpreted as a phlebotomy scar. Tere was also a higher risk for iatrogenic injury related to persistent pain in a transverse incision [9,13].
Te most similar technique to ours was that of Liverneaux et al. However, there are several diferences. Tey used regional rather than general anesthesia and performed reduction prior to surgery. In addition, our study used a smaller plate to allow the use of shorter incisions. Liverneaux also used several maneuvers to reduce the fracture by open means, including the "tyre changer maneuver," in which a periosteal elevator was inserted into the fracture site's volar aspect; the "dorsal leverage maneuver," in which percutaneous K-wire was inserted into the fracture site's radial aspect, and the "compression maneuver," in which a compression screw passed through the oblong hole [5].
Our study preferred closed reduction using various maneuvers. After reduction, K-wires were inserted to provisionally maintain the reduction. Ten, the plate was applied to the radius's anterior cortex for fxation. Arthroscopy was used for intraarticular involvement. Te procedure we performed was analogous to internal fxation using cephalomedullary nailing, resulting in the advantages of good softtissue preservation, radiographically measurable reduction, and a relatively short elapsed time from incision to wound closure. Biz et al. also used additional K-wires, fnding them associated with better clinical outcomes in the elderly and younger adults. Additional K-wires may provide additional stability to the fracture area. However, they did not use plates as the main fxator to the fracture [14].
It should also be noted that Liverneaux used a lift-of technique, which cannot be used for comminuted fractures,   Minimally Invasive Surgery fractures with relatively thin and distally located fragments, and osteoporotic lesions. Tis technique was required because the procedure that Liverneaux proposed used strength/integrity from the distal part. Terefore, this procedure may lead to pull-out in cases where distal integrity is absent.
It must be noted that using smaller and shorter plates for MIPO in distal radius fracture cases has not been previously reported. Based on our experience, using smaller and shorter plates had several advantages, such as being easier to perform and safer for adjacent soft tissues. Wrong plate size may impede adequate bone healing and lead to displacement after follow-up. However, the fracture remained stabilized, and no complications, such as secondary displacement, occurred. Terefore, we recommend using smaller and shorter plates in MIPO to make the procedure easier and to optimize patient outcomes.
Outcome measurements indicated satisfaction in our patients. It should be noted that ROM and VAS signifcantly improved between the postoperative and three-month follow-ups (p < 0.05). Subjective measurements using the DASH score also indicated improvement at three months postoperative (p < 0.05). A similar result was observed in postoperative VAS scores, with the procedure resulting in    patients, all of whom reported complete healing and excellent wrist function based on DASH score, ROM, and grip strength [15]. In high-energy trauma or articular involvement, arthroscopy is preferred to reduce osteochondral fragments and repair scapholunate lesions after plate fxation. A similar procedure was performed by Zemirline et al., who also showed satisfactory functional outcomes using the DASH score. Te advantage of using arthroscopy was that it allows better reduction and assessment of lesions adjacent to the fracture. Tey used an incision of 15 mm in the anterior, the same as in our cases. Smaller incisions are associated with aesthetic scars and better patient satisfaction [8].
A major drawback of this procedure is radiation exposure due to fuoroscopy, which produces harmful ionizing radiation. Radiation efects can be divided into stochastic and deterministic types [16]. Stochastic efects have no threshold dose, and as exposure increases, the possibility (rather than the intensity) of the efect increases. Tere are long-term consequences, such as genetic damage and cancer, caused by radiation. Deterministic efects are dosage dependent and require a minimum threshold dose to manifest. Below that dose, no efect occurs. Skin damage is the most common deterministic adverse efect of fuoroscopy radiation exposure. Furthermore, the steep learning curve and technical difculties may hinder this technique's development. Consequently, reducing radiation exposure and the learning curve is important for the patient's procedure success and surgical outcome.
Tis case series also had limitations. It included various fracture types, which may afect surgical outcomes. Some fractures had intraarticular involvement, which was addressed using arthroscopy. Some patients also had simultaneous TFCC injuries, which required repair. Furthermore, since this study only had a small subject size, its fndings are not conclusive. Despite its heterogeneity, the modifed MIPO proposed by our study resulted in comparable functional outcomes with shorter surgery times. A prospective study with the same baseline characteristics may provide more information with less bias.

Conclusions
MIPO in managing distal radius fractures was associated with satisfactory clinical outcomes and reproducible and consistent results. Smaller plates provided a simpler but reliable method with no reported complications after the follow-up period. However, further studies with homogenous fracture types and longer follow-up periods are needed to confrm our fndings.

Data Availability
Te patient's detailed data used to support the fndings of this study are available from the corresponding author upon request.

Conflicts of Interest
Te authors declare that there are no conficts of interest.