Minimally invasive plate osteosynthesis for distal radius fractures using a 3-point positioning technique

doi:10.21203/rs.3.rs-3195745/v1

In this study, we perform a retrospective analysis of the mid-term clinical results of distal radius fractures treated with the 3-point positioning technique using a minimally invasive plate osteosynthesis (MIPO) while preserving the pronator quadratus (PQ). The 3-point positioning technique was applied: the Kirschner wire was inserted after fluoroscopy and was correctly adjusted the position of the plate above the PQ. With the aid of Kirschner wires positioning the PQ stripping was performed only once, and the plate then placed in a correct and satisfactory position. Operation time, incision length, wrist pain score, upper extremity function DASH score, wrist Gartland-Werley score, wrist grip strength, and range of motion (ROM) were among the quantitative variables recorded. Qualitative variables including AO fracture classification, intraoperative and postoperative complications were evaluated. Twenty patients were enrolled in the study with an average follow-up of 6.8 ± 0.76 months. Of these, 8 males and 12 females were enrolled. the DASH score for the upper limb was 4.7 ± 1.3, and the Gartland-Werley score for wrist function was 11.9 ± 2.5 at the last follow-up. Mean flexion was 97.3%, extension was 97.1%, pronation was 98.8%, supination was 98.6%, and grip strength was 86.1% compared to contralateral values. No unfavorable intraoperative or postoperative complications occurred. The 3-point positioning technique can greatly minimize the damage to the PQ muscle and is a safe and effective method for MIPO for distal radius fractures.

Health sciences/Anatomy/Musculoskeletal system/Muscle

Health sciences/Diseases/Trauma

Fractures of the distal radius are the most frequent. Conservative treatment mainly includes casts, braces, and other methods. The methods of surgery involve open reduction plate internal fixation, external fixation, and minimally invasive percutaneous Kirschner wire fixation. The PQ muscle is incised through the Volar approach and internal fixation with a plate is the most commonly used surgical treatment¹. Whether to repair the PQ muscle in the Volar Henry approach is still controversial. Nevertheless, a PQ injury can also, indirectly, irritate the Flexor palmar tendon, damage the distal radius's blood supply, lessen the stability of the distal radioulnar joint, and decrease the forearm's pronation strength by up to 21%². As a result, numerous researchers started to investigate the technique of putting a plate below the PQ without severing it, and they have had positive clinical outcomes^3,4. However, we discovered in our clinical experience that when utilizing the conventional MIPO method, it takes an average of 3–4 adjustments of the plate using intraoperative fluoroscopy to position the plate correctly. The PQ muscle is a closed compartment without an intermuscular septum⁵. During the minimally invasive plate placement, the plate may be placed on the radial or ulnar side during the operation, and it needs to be confirmed to be adjusted to the correct position under fluoroscopy. The process of adjustment will inevitably lead to the destruction of the starting and ending points of the PQ muscle on the ulnar and radial sides. Using the conventional minimally invasive method of preserving the PQ muscle, which is not strictly preserved and undamaged in practice. Therefore, we propose a 3-point positioning technique to truly protect the PQ muscle. This study retrospectively analyzed the data of 20 patients with distal radius fractures treated by our 3-point positioning technique to evaluate the functional outcome and complications of this method.

The Human Experimentation and Ethics Committee of our hospital's institutional review board gave its approval to the study's design and data collection (2023101). We reviewed the records of 50 patients who underwent MIPO for distal radius fracture between January 2019 and February 2021. Due to inadequate data, a follow-up of less than 6 months, concurrent bilateral fractures, or bone and ligament abnormalities in the wrist, 30 cases had to be removed. Adults with recent fractures (2 weeks), no accompanying lesions, and more than 6 months of follow-up were included in the study. The series thus consisted of 20 patients, 8 males and 12 females, who were all classified by AO/ASIF. The patients included type A2 (n = 5), type A3 (n = 3), type B1 (n = 5), type B3 (n = 5), type C1 (n = 5), and type C2 (n = 1) individuals. This study did not include patients who had distal radius fractures of types A1, B2, or C3.

Operative procedure

All patients were anesthetized with a brachial plexus block and placed on a radiolucent table. Following the onset of anesthesia, closed manual reduction was performed on all patients. A 15mm diameter Kirschner wire was inserted from the styloid process of the radius to the ulnar side of the proximal fracture to retain the initial anatomical parameters after preliminary acceptable fracture reduction was confirmed by fluoroscopy (Fig. 1). The surgical incision was created of the flexor carpi radialis radial margin being extended under the transverse carpal line to the proximal end 2.5cm (Fig. 2a). After exposing the flexor carpi radialis tendon, it was pulled ulnarally along with the median nerve, the radial artery was pulled radially, and the PQ was exposed (Fig. 2b). In distal radius fractures, the distal margin of the PQ is often split by the fracture end. If not, we cut it transverse and then lifted the distal edge of the PQ from the subperiosteum of the radius and performed fracture reduction (Fig. 2c). In the traditional MIPO method, the plate is inserted below the PQ in the next step (Fig. 2d). In our clinical practice we have found that it takes an average of 3–4 adjustments to place the plate in the correct position under the PQ, which inevitably leads to the injury of the PQ (Fig. 2e-h). We position the volar anatomic locking plate at the distal radius above the PQ in our modified 3-point positioning technology, with the distal end placed at the watershed line of the distal radius (Fig. 3a). Two 15mm Kirschner wires were inserted into the radial and ulnar screw holes at the plate’s distal end and passed through the dorsal cortex to temporarily anchor the plate after fluoroscopy confirmed its satisfactory position. To determine the position of the plate on the radial axis, a 15mm Kirschner wire was positioned close to the ulnar border of the central portion of the plate (Fig. 3b, c). The plate was removed after the three Kirschner wires had been trimmed to a length of roughly 0.5 cm and left in place. Between the two Kirschner wires at the distal end and close to the radial border of the Kirschner wire at the proximal end, a subperiosteal dissection of the PQ was performed (Fig. 3d). The locking hole of the plate's distal radial and ulnar sides were "wore" into the two shorted Kirschner wire posts at the distal end after the plate was inserted into the tunnel from the radial edge of the proximal Kirschner wire (Fig. 3e, f). The screw was placed for fixation after fluoroscopy to ensure that the position of the plate was suitable. The 3-point positioning technique was utilized to prevent harm to the PQ muscle from cutting during multiple adjustments and to ensure that the plate could be put in the proper position following a single dissection of the muscle (Fig. 3). The remaining screws were inserted to complete the final fixation, and the surgical incision was irrigated and closed layer by layer. No external immobilization was used. Early active hand clenching and relaxation exercises were performed 6 to 8 hours following surgery. Active and passive wrist flexion and extension and forearm rotation training were started 24 h after surgery. The corresponding training intensity was guided according to the type of fracture and wound healing of patients.

Assessment

The operation time, incision length, postoperative radial inclination (RI), volar tilt (VT), and ulnar variance (UV) were recorded. At the initial follow-up, at 1-, 3-, and 7 days following surgery, at 3 weeks after surgery, and the last follow-up visit. Wrist pain was assessed using the visual analog scale (VAS). At 3 weeks following surgery and the final follow-up, the upper extremity function score (DASH, disabilities of the arm, shoulder, and hand outcome measure)⁶ and the Gartland-Werley score⁷ of wrist function were evaluated. On the operative and contralateral sides, the ROM (flexion, extension, pronation, and supination) and grip strength measured in kilogram-force (kgf) with a Jamar® hydraulic dynamometer (Per-performance Health, Reims, France) were assessed and compared at the last follow-up visit. Both intraoperative and follow-up complications were recorded.

Twenty patients with a mean age of 44.9±13.30 years (range, 22-71 years) were followed up for a mean of 6.8±0.76 months (range, 6-9 months). The average length of an incision was 25.1±1.4 mm (range, 23-28 mm). The mean operative time was 43.1±3.7 min (range, 38-50 minutes). The mean RI, VT, and UV were not significantly different from the contralateral side (Table 1). In comparison to the mean pain score 3 weeks following surgery, the mean pain score at the last follow-up, 0.7±0.6 (range, 0-2) was significantly different. The DASH score at 3 weeks following surgery (11.5±2.0) differed considerably from that at the last follow-up (4.7±1.3). The difference between the Gartland-Werley score at the last follow-up (4.1±1.0) and the score at 3 weeks following surgery (11.9±2.5) was also statistically significant (Table 2). A comparison of ROM and grip strength is shown in Table 3 for both the operational and contralateral sides. Pronation was 98.8%, supination was 98.6%, flexion was 97.3%, extension was 97.1%, and grip strength was 86.1% when compared to the contralateral side (Table 3). These measurements showed a statistical reduction in function compared to the contralateral side (P<0.01). No complications such as poor wound healing, infection, iatrogenic vascular or nerve injury, malunion, or failure of fixation were observed in any patient (Fig. 4).

As a result of improvements in medical technology and the quest for aesthetically pleasing surgical incisions, minimally invasive techniques are now performed in all medical specialties. Imatani and Tobe were pioneers in proposing the concept of minimally invasive treatment of distal radius fractures^8,9. Since their report, some researchers¹⁰ have utilized a 1 cm incision to do the procedure, because of ongoing technical developments. However, a minimally invasive strategy for treating distal radius fractures entails more than merely making tiny incisions. The key to minimally invasive treatment of the distal radius fracture is minimum interference with several important surrounding tissues, no harm to the PQ, no dissection of the radial artery or median nerve, and no dissection of the joint capsule or ligament appendages. In particular, the PQ can increase the distal radioulnar joint's stability, supply blood to the distal radius to aid in fracture healing, and provide 21% of the forearm's pronation strength, and an unharmed PQ will also increase the postoperative pronation angle and lessen tendon injury and irritation^2,11.

Sotereanos et al.⁵ confirmed that the PQ muscle is a closed compartment without a muscle septum by injecting image enhancement agents into cadaveric specimens under fluoroscopy, and its muscle bundle starts from the front and medial side of the lower 1/5 of the ulna and ends on the palmar and anterior edge of the lower 1/5 of the radius. However, conventional minimally invasive treatment of distal radius fractures requires blind penetration of the plate under the PQ muscle at the proximal radius. The plate may be placed on the radial or ulnar side during the procedure, and the position needs to be confirmed and adjusted under fluoroscopy. In our clinical practice, we have learned that it takes an average of three to four adjustments to get the plate under the PQ in the correct position. There is no doubt that the process of adjustment will inevitably lead to the cutting and destruction of the PQ muscle at the starting and ending edge of the palmar surface of the lower 1/3 of the radius. In other words, this minimally invasive method of preserving the PQ is not strictly preservative and non-destructive. At the same time, due to the nature of the minimally invasive procedure used, damage to the PQ muscle during the procedure could not be verified or repaired under direct vision. Therefore, the actual soft tissue injury of the minimally invasive incision may be more severe when unrepaired as opposed to the usual large incision open reduction and repair under direct vision. In this study, the "3-point positioning method" is proposed, in which the plate was placed above the PQ muscle in advance, and the exact position of the plate was adjusted by fluoroscopy above it. Three Kirschner wires were used to position the plate, and a unique and relatively accurate dissection and placement of the plate under the periosteum of the PQ muscle was performed between the Kirschner wires at the pile-point to minimize damage to the PQ muscle.

The 3-point positioning method was used to treat patients in this clinical investigation, and it was found to have advantages for early postoperative wrist pain relief, wrist joint activity, and functional recovery. The wrist function of the patients was assessed using the Gartland-Werley scale in this study, with pain serving as the primary predictor. In the palmar approach for distal radius fractures, Itoh et al.¹² compared two alternative ways to dispose of the PQ: one method preserved the muscle, while the other incise the muscle and then repair it with sutures. The outcome demonstrated that the wrist pain scores of the PQ preservation approach were lower at 2, 3, and 4 months after surgery. Häberle et al.¹³ also demonstrated that MIPO used to treat distal radius fractures while protecting the PQ was effective in minimizing postoperative pain within 6 weeks of surgery. Early postoperative wrist pain scores were lower with our study's 3-point positioning method patients than they were in other published studies^14,15. Among the reasons may be that the technique causes less damage to the PQ muscle, less swelling of the muscle's soft tissue in the early postoperative period, and less tearing pain in the injured muscle caused by early exercise. The anatomical position and physiological function of the PQ are not impaired, which better isolates the contact of the internal fixation with the tendon and thus avoids irritating it. As a result, patients had lower levels of early pain and were able to achieve better Gartland-Werley scores.

In the early post-operative period, Mehmet et al.¹⁶ revealed an average loss in forearm pronation strength of about 18.5%, with the forearm pronation durability test indicating a loss of up to 12.9%. Lidocaine was used by McConkey et al.¹⁷ to test the contribution of the pronator quadrate to pronation by paralyzing the pronate quadrate. They found that paralysis reduced the pronation of the forearm by 16.7–23.2%. If the PQ suture was not completed it was observed that the forearm pronation strength was decreased by 22% at a 1-year follow-up after surgery¹⁸. Of course, some reports have proposed that the repair of the PQ muscle has no effect on the follow-up results of joint rotation and range of motion and believe that the weakening or loss of the PQ muscle function can be compensated for by the pronator teres muscle and the flexor carpi radialis muscle so that the forearm rotation function can be preserved^19,20. However, we believe that the anatomy of each physiological presence has its distinct meaning. The PQ, if repaired or only slightly damaged, can alleviate pain in the early postoperative period, allowing patients to achieve better postoperative rom and grip strength, and reducing flexor tendon irritation. Fan et al.²¹ also suggested that in the early stage of recovery, the preserved or repaired PQ muscle has better pronation ability and lower pain scores.

In terms of surgical indications Kiyohito¹⁰ considered that for type C2 and C3 fractures with a comminuted articular surface, the patient should be carefully selected, and wrist arthroscopy should be assisted if necessary. However, for a type C1 distal radius fracture, they believed that a small minimally invasive incision of 1.0 cm could also achieve satisfactory efficacy. For type B2 fracture, it should be used with caution because it is difficult to effectively expose and fix with minimal invasion. According to this study, it is best to use caution when selecting a minimally invasive treatment for distal radius fractures of type C3. The traditional surgical approach should be chosen as soon as feasible if exposure and fixation are challenging throughout the procedure.

The 3-point positioning technique has the advantage of requiring only a single dissection of the PQ, thereby preventing injury to the muscle caused by repeatedly adjusting the position of the plate underneath the muscle during the traditional MIPO technique. The plate is tagged with Kirschner wires and prepositioned over the PQ muscle, which is the fundamental originality of this technique. The main innovation of this method is that the plate is placed above the PQ muscle, and the Kirschner wires were inserted as the pile-point after the correct position is confirmed. Finally, the plate was "wore" into the pile-point. If the fracture is relatively comminuted, 2 to 3 Kirschner wires (1.0 mm and 1.5 mm) can be percutaneously placed from the radial edge of the radius to the ulnar side to maintain the reduction and ensure that the plate placement is not interfered with. A modest proximal percutaneous incision should be created for implanting the most proximal screw if it is challenging to do so. Pay attention to gentle manipulation. The assistant can reduce the tension of the incision by flexing the wrist joint and drifting the gap within the incision to achieve satisfactory exposure and fixation. The plate should be carefully inspected after implantation to see if tendons, vital arteries, and nerves are entrapped before final fixation is performed. After fixation, the wrist and metacarpophalangeal joint extreme extension and flexion were utilized to assess if the tendon was noticeably compressed. This study also suggests that attention should be paid to the learning curve of this method. Only proficient surgical techniques and skilled surgical team cooperation can achieve satisfactory results.

In this paper, the "3-point positioning technique" was used to treat distal radius fractures, which minimizes the damage of the PQ muscle in the real sense and achieves satisfactory mid-term clinical results. Although it was a retrospective study and there weren't many cases, this technical innovation is worthy of further refinement, research, and eventual promotion.

Availability of data and materials: All data generated or analysed during this study are included in this published article and support our published claims and comply with field standards [Supplementary datasets].

Author contribution: All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Zhaoqing Shen, Chunling Wu. The first draft of the manuscript was written by Youyou Ye and all authors commented on previous versions of the manuscript. Yanbin Lin: design of the study, surgery and general supervision of the research group. All authors read and approved the final manuscript.

Conflict of interest: The authors declare no competing interests.

Ethics approval: All procedures in studies involving human participants were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Ethical approval was obtained from the Medical Ethics Review Committee of the Fuzhou Second Hospital, The Third Clinical Medical College, Fujian Medical University, Fuzhou Second Hospital of Xiamen University, School of Medicine, Xiamen University (approval No. 2023101).

Funding: The authors received financial support from Fujian Provincial Clinical Medical Research Center for First Aid and Rehabilitation in Orthopaedic Trauma (2020Y2014).

Consent to publish: The authors affirm that human research participants provided informed consent for publication of the images in Figure (1-4).

Consent to participate: Informed consent was obtained from all individual participants included in the study.

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Table 1 Early postoperative radiological indicators were compared with those of the contralateral side

Index	Operation side	Contralateral side	t	p
^★Volar tilt	12.9±1.1	13.0±0.86	-0.16	0.87
^★Radial inclination	19.8±1.3	19.9±1.5	-0.11	0.91
*Ulnar variance	-0.83±0.11	-0.85±0.12	-0.56	0.58

^★Volar tilt and radial inclination are measured in degrees(degrees±SD)

*Ulnar variance is measured in millimetres (mm±SD)

Table 2 Wrist pain, Gartland-Werley score and DASH score were followed up after operation

Index	^★POD 1	^★POD3	^★POD7	^★POW3	Finally follow-up
*VAS	4.9±0.7	3.4±0.7	2.5±0.6	1.5±0.6	0.7±0.6
DASH score	-	-	-	11.5±2.0	4.7±1.3
Gartland-Werley score	-	-	-	11.9±2.5	4.1±1.0

^★POD: Postoperative Day(`X±SD); ^★POW3:Postoperative 3 Week(`X±SD)

*VAS: visual analog scale (`X±SD)

Table 3 Range of motion (ROM) and grip strength at the last follow-up were compared with those of the contralateral side

Variable	Operation side	Contralateral side	t	p
^★Flexion	54.2±1.96	55.7±2.45	-2.14	0.04
^★Extension	60.9±1.1	62.7±1.5	-4.6	<0.0001
^★Pronation ^★Supination *Grip strength	88.1±1.3 86.6±1.4 21.7±3.7	89.1±0.8 87.8±1.1 25.2±4.8	-2.95 -3.09 -2.59	0.006 0.004 0.013

^★ROM is in degrees (degrees±SD)

*Grip strength is in kilogram-force (kgf) (`X±SD)

No competing interests reported.

Supplementarydatasets.zip

Minimally invasive plate osteosynthesis for distal radius fractures using a 3-point positioning technique

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Abstract

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Introductions

Materials and methods

Operative procedure

Assessment

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Discussion

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References

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