The Effect of Plate Location on Radial Nerve Palsy Recovery Time Associated with Humeral Shaft Fractures Zeki Günsoy (  zekigunsoy@gmail.com ) Bursa City Hospital Gökhan Sayer Bursa City Hospital Mustafa Dinç Bursa City Hospital Ömer Cevdet Soydemir Bursa City Hospital Sinan Oğuzkaya Bursa City Hospital Research Article Keywords: Posted Date: January 25th, 2024 DOI: https://doi.org/10.21203/rs.3.rs-3890983/v1 License:   This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Additional Declarations: No competing interests reported. Page 1/12 Abstract BACKGROUND This study aims to investigate the influence of plate placement on nerve regeneration in humerus fractures accompanied by radial nerve injury. METHODS A retrospective analysis was conducted on a cohort of 94 patients with humerus fractures and concomitant radial nerve injury treated between January 2018 and November 2022. After applying exclusion criteria, 31 patients were included in the study. Clinical outcomes were assessed by comparing demographic data, surgical duration, radial nerve recovery time, the Mayo Elbow Performance Score (MEPS), Disabilities of the Arm Shoulder and Hand (DASH), and the Medical Research Council (MRC) scale. RESULTS Two distinct groups were established: lateral plating and anteromedial (AM) plating. These groups demonstrated comparability regarding age, gender, and body mass index (BMI). No statistically significant differences were observed between the groups concerning MEPS and MRC. The AM plating group notably exhibited shorter surgical durations, faster recovery times, and lower DASH scores. CONCLUSION According to the findings of this investigation, in cases of humerus fractures accompanied by radial nerve injury, AM plating may be preferable over lateral plating due to its association with reduced surgical durations, expedited nerve recovery, and superior functional outcomes. INTRODUCTION Humeral fractures are frequently complicated by radial nerve palsy. The incidence of radial nerve injury after humeral shaft fractures is 8%, representing the most common peripheral nerve injuries second to long bone fractures [1]. The radial nerve's fixed position and direct contact with the periosteum while rotating in the spiral groove and passing through the lateral intermuscular septum of the arm can be shown as the reasons for its vulnerability to injury [2]. Fractures occurring at these levels can easily damage the radial nerve. These injuries can vary from neuropraxia to complete neurotmesis [3]. Occurring oblique or spiral fractures threaten the radial nerve mainly on the middle and distal one-third portions due to the anatomical localization of the radial nerve [4]. In addition to occurring during traumas, radial nerve injury can iatrogenically occur during closed manipulations, plating, and intramedullary nailing [5]. Page 2/12 Although the exploration indication for radial nerve injuries with open fractures is clear, the exploration indication and timing of closed fractures are debatable [6–8]. Even though high recovery potential has distracted surgeons from exploration in conservatively monitored cases, studies in the literature defend radial nerve exploration in the early stages [9]. In the last decade, 11.2–12.1% of radial nerve palsy, which accompanies humeral fractures, does not recover and is treated with nerve or tendon transfers [6, 9]. Much research has been devoted to the effects of patient characteristics (age, chronic diseases, smoking), fracture type, injury mechanism, choice of implant, and accompanying soft tissue injuries on recovering radial nerve injury [6–15]. However, no studies were found in the literature about the effect of the plate location on nerve recovery in patients treated with plating. This study aimed to determine the effect of plate placement on nerve recovery in humeral fractures with radial nerve injury. It was hypothesized that due to differences in the nerve and contact area, using anteromedial plating would be superior to lateral plating in terms of radial nerve recovery and functional scores. MATERIAL and METHOD Clinical ethics committee approval (2022-14/12) dated 26.10.2022 was granted, and written information consent from all patients was obtained before initiating this single-center retrospective study. The study was conducted on the data of the patients obtained between December 2019 and November 2022 who had humeral fractions accompanying radial nerve injury and was performed at a third-step university hospital (a trauma and microsurgery center). Patient Selection Ninety-four patients whose humeral fracture was accompanied by a radial nerve injury and who were surgically treated were included in the study. Surgical treatment was indicated in 1) patients whose closed reduction failed (in 20° coronal − 30° sagittal plane 15° rotational deformation and shortness more than 3 cm), [16, 17], 2) patients with open fractures, and 3) patients with vascular injuries. Inclusion criteria: Having applied between January 2018 and December 2022, older than 18 years and who had regular medical records, 1) closed fractures, 2) anteromedial or lateral plate placement performed using anterolateral incision, 3) who had Seddon’s type 1 radial nerve injury, (whose nerve integrity was intact including epineurium in intraoperative exploration, and had radial nerve symptoms due to conduction failure) 4) who had Arbeitsgemeinschaft für Osteosynthesefragen (AO) type 12 fractures, and 4) being followed-up for a minimum of 12 months. Exclusion criteria: 1) having radial nerve injuries other than Seddon’s type 1 (intraoperatively observed), 2) AO type 13 humeral fractions, 3) conservative treatment, 4) being fixed with an external fixator and intramodular nail, 5) being outside the determined age range, and 6) having a disease such as polyneuropathy or diabetes that affects neural recovery. Page 3/12 The patient selection process is summarized in Fig. 1. Surgical Method A senior upper extremity surgeon performed all of the operations. Concerning medication, 1000 mg of cefazolin was administered as an antibiotic prophylaxis. The patients were operated on under general anesthesia in the beach chair position. An anterolateral incision was used in both groups, the radial nerve was explored, nerve integrity was evaluated under loop magnification, and Seddon’s Type 1 injury was confirmed. After fracture hematoma debridement, a limited-contact dynamic compression plate (LC-DCP) (Tıpmed-İzmir) was applied with fracture reduction. Lateral plating was performed between January 2018 and December 2021, and then all patients received anteromedial plating (Fig. 2) since the evidence showed that AM plating has significant advantages over lateral plating [18, 19]. None of the fractures was shortened. Postoperative Rehabilitation All patients received the same standard postoperative protocol and were followed up by the same physiotherapist beginning on the day of the operation. Passive wrist, elbow, and pendulum exercises started on the third postoperative day. Patients were instructed to conduct active elbow and shoulder movements as much as they could tolerate. They were not allowed to lift weights until their radiological union was confirmed. Patient Follow-up The patients’ data, such as age, sex, body mass index, fracture classification, and trauma etiology, were recorded in their first emergency room referral. The operation time was documented and compared between the two groups. Nerve follow-ups of the patients were conducted weekly with physical examination, and union evaluations were done monthly on two-way graphs. The patient follow-up was discontinued when the nerve and bone union were confirmed. Union and nerve recovery times of the patients were recorded at regular follow-ups. Fracture union was defined as no pain in the fracture line and the appearance of bridging calluses of at least three out of four cortices on X-ray [20]. Nerve recovery was defined according to the normalization of the total finger and wrist movements [21]. The Mayo Elbow Performance Score (MEPS), Disabilities of the Arm Shoulder and Hand (DASH), and Medical Research Council (MRC) scale and elbow flexion power were used to evaluate the functional results. The operating surgeon performed clinical and radiological follow-ups [22–24]. Statistical Analysis The data conformity to the normal distribution was assessed with the Shapiro-Wilk test. In the case of normal distribution, comparisons between the groups were made with the t-test, and descriptive values were given as the mean ± standard deviation (Table 1). Intergroup comparison of the categorical data was created with the chi-squared test, Fisher’s exact test, and Fisher–Freeman-Halton test, and descriptive Page 4/12 statistics were given as the frequency and percentage. α = 0.05 was accepted as the statistical significance level. Data analysis was done with IBM SPSS Statistics for Windows 25.0 (IBM Corp., Armonk, NY, USA). RESULTS Thirty-one patients were included in the study (18 males, 13 females) with a mean age of 43,19 ± 12,14; further baseline information is presented in Table 1. The operation time was lower in the AM plating group (97.87 ± 12.91 min vs 112.88 ± 13.33 min; p = 0.003). The nerve recovery time was faster (p < 0.001), and the mean DASH score was higher (p = 0.019) in the AM plating group (Table 2). All patients showed complete union and complete nerve recovery was established. DISCUSSION This study particularly supports the idea that anteromedial plating is an easier choice and contributes to nerve recovery duration than lateral plating. This might have resulted from disturbing the microcirculation due to mobilizing the radial nerve more while performing lateral plating. Moreover, having no contact between the plate and nerve during anteromedial plating could have been a secondary reason for the short duration. Another important finding of the study was the significantly higher DASH score in patients with anteromedial plating than those with lateral plating. This can be associated with the short nerve recovery duration with anteromedial plating. Early nerve recovery might be effective in early muscle reinnervation and muscle mass maintenance. Earlier innervated muscle with earlier active movement might have positively affected the patients’ functions. Previous studies analyzing the effect of anteromedial and lateral plating on iatrogenic radial nerve injury showed that applying anteromedial plating prevents radial nerve mobilization and protects the medial microvascular structures [25, 26]. In their research, Kirin et al. compared the patients who were performed 141 anteromedial and 279 lateral plates and showed that there was no radial nerve injury in the anteromedial plate group; however, 32 (11.15%) patients showed radial nerve palsy in the lateral plate group [25]. Additionally, Cognet-Verga et al. examined the revision cases. They indicated that the entrapment of the radial nerve in the intermuscular septum and its direct contact with the plate can cause paralysis in the intact nerve [27]. The nerve excursion is very low compared to muscles and tendons [28]. Suwannaphisit et al. showed that the radial nerve reached its maximum excursion within 4–6 cm proximal to the lateral epicondyle [29]. The laterally placed plate can disturb this excursion, and as a result, increased nerve tension can disturb microcirculation. Thus, the plate’s position can cause nerve palsy and determine the recovery process [30–32]. Chamseddine et al. suggested medial transposition along the fracture line to avoid nerve tension Page 5/12 and plate contact [33]. In agreement with the literature, it was found in the current study that the nerve recovery duration was earlier with anteromedial plating compared to lateral plating. Open reduction and plate osteosynthesis remain the gold standard for humeral shaft fractures when surgery is indicated [34]. Many options can be used depending on the surgeon’s experience, the fracture pattern, and concomitant injuries. In addition to conventional lateral plating, the posterior approach, anterior plating with the anterior approach, anteromedial plating with the anterolateral approach, and minimally invasive techniques can be used. Each method has its advantages and disadvantages. In their study, Van de Wall et al. analyzed 102 patients treated with plate fixation for humeral shaft fracture, and they showed that anterolateral plating is a risk factor for adverse outcomes [35]. In addition to iatrogenic radial nerve injury risk, impaired shoulder function is another concern with lateral plating[36, 37]. Rai et al. stated that since the anteromedial plating does not require radial nerve exploration, it is easier and faster to apply [18]. In addition, Kirin et al. displayed that in terms of surgical time, anteromedial plating is more rapid than lateral plating [25]. Similar to the literature, the present study found that the anteromedial plating duration was shorter than that of lateral plating. This difference in the surgical duration may have been due to the more significant radial nerve decompression during the lateral plate placement. Anteromedial plating with an anterolateral approach offers significant advantages such as a more straightforward application of plate to the anteromedial surface of the humerus; no muscle split is necessary during surgical dissection, no risk of impaired shoulder function due to deltoid irritation, and plate removal is more manageable without the risk of radial nerve injury [18]. In addition to the previously documented advantages of anteromedial plating with an anterolateral approach, the findings support that anteromedial plating allows faster radial nerve recovery, which is vital for more rapid rehabilitation, return to work, and daily life. This study was conducted on a highly selected population. All patients were operated on, followed up by a senior upper extremity surgeon, and received the same postoperative protocol. This is the first study that has evaluated the relationship between the plate position and radial nerve recovery time in humeral shaft fractures. The study's retrospective design, the limited number of patients, the different injury mechanisms, and the energy that can affect nerve recovery are among the limitations of this study. Prospective studies with more patients, homogeneous injury mechanisms, and fractures that occur in similar energies are required in the literature. In conclusion, in humeral shaft fractures with radial nerve injury, anteromedial plating with an anterolateral approach is related to higher functional results, less time to radial nerve recovery, and less operation time than lateral plating. DECLARATIONS Page 6/12 Author Contribution Z.G. performed surgeries, Z.G. and G.S. wrote the main article,M.D. collected patients' records,Ö.CS. made biostatics, S.O. edited the article REFERENCES 1. Ekholm R, Adami J, Tidermark J, Hansson K, Törnkvist H, Ponzer S: Fractures of the shaft of the humerus. An epidemiological study of 401 fractures. J Bone Joint Surg Br 2006, 88(11):1469-1473. 2. Carlan D, Pratt J, Patterson JM, Weiland AJ, Boyer MI, Gelberman RH: The radial nerve in the brachium: an anatomic study in human cadavers. J Hand Surg Am 2007, 32(8):1177-1182. 3. Seddon H: Three types of nerve injury. Brain 1943, 66(4):237-288. 4. Theeuwes HP, van der Ende B, Potters JW, Kerver AJ, Bessems J, Kleinrensink GJ: The course of the radial nerve in the distal humerus: A novel, anatomy based, radiographic assessment. PLoS One 2017, 12(10):e0186890. 5. Wang JP, Shen WJ, Chen WM, Huang CK, Shen YS, Chen TH: Iatrogenic radial nerve palsy after operative management of humeral shaft fractures. J Trauma 2009, 66(3):800-803. 6. Shao YC, Harwood P, Grotz MR, Limb D, Giannoudis PV: Radial nerve palsy associated with fractures of the shaft of the humerus: a systematic review. J Bone Joint Surg Br 2005, 87(12):1647-1652. 7. Li Y, Ning G, Wu Q, Wu Q, Li Y, Feng S: Review of literature of radial nerve injuries associated with humeral fractures-an integrated management strategy. PLoS One 2013, 8(11):e78576. 8. Rocchi M, Tarallo L, Mugnai R, Adani R: Humerus shaft fracture complicated by radial nerve palsy: Is surgical exploration necessary? Musculoskelet Surg 2016, 100(Suppl 1):53-60. 9. Ilyas AM, Mangan JJ, Graham J: Radial Nerve Palsy Recovery With Fractures of the Humerus: An Updated Systematic Review. J Am Acad Orthop Surg 2020, 28(6):e263-e269. 10. Apivatthakakul T, Patiyasikan S, Luevitoonvechkit S: Danger zone for locking screw placement in minimally invasive plate osteosynthesis (MIPO) of humeral shaft fractures: a cadaveric study. Injury 2010, 41(2):169-172. 11. Belayneh R, Littlefield CP, Konda SR, Broder K, Kugelman DN, Leucht P, Egol KA: The standardized exploration of the radial nerve during humeral shaft fixation reduces the incidence of iatrogenic palsy. Arch Orthop Trauma Surg 2023, 143(1):125-131. 12. Bleeker WA, Nijsten MW, ten Duis HJ: Treatment of humeral shaft fractures related to associated injuries. A retrospective study of 237 patients. Acta Orthop Scand 1991, 62(2):148-153. 13. Pailhe R, Mesquida V, Rubens-Duval B, Saragaglia D: Plate osteosynthesis of humeral diaphyseal fractures associated with radial palsy: twenty cases. Int Orthop 2015, 39(8):1653-1657. 14. Streufert BD, Eaford I, Sellers TR, Christensen JT, Maxson B, Infante A, Shah AR, Watson DT, Sanders RW, Mir HR: Iatrogenic Nerve Palsy Occurs With Anterior and Posterior Approaches for Humeral Shaft Fixation. J Orthop Trauma 2020, 34(3):163-168. Page 7/12 15. Venouziou AI, Dailiana ZH, Varitimidis SE, Hantes ME, Gougoulias NE, Malizos KN: Radial nerve palsy associated with humeral shaft fracture. Is the energy of trauma a prognostic factor? Injury 2011, 42(11):1289-1293. 16. Klenerman L: Fractures of the shaft of the humerus. J Bone Joint Surg Br 1966, 48(1):105-111. 17. Shields E, Sundem L, Childs S, Maceroli M, Humphrey C, Ketz JP, Soles G, Gorczyca JT: The impact of residual angulation on patient reported functional outcome scores after non-operative treatment for humeral shaft fractures. Injury 2016, 47(4):914-918. 18. Rai SK, Sud AD, Kashid M, Gogoi B: Anteromedial Surface Plating for Midshaft Fracture Humerus Through an Anterolateral Approach - A Better Option than Anterolateral Plating. Malays Orthop J 2020, 14(3):66-72. 19. Ahmed M, Bux M, Ahmed N, Kumar M, Ishtiyaque M, Hussain G: Shaft of humerus fracture managed by anteromedial plating through anterolateral approach. The Professional Medical Journal 2021, 28(06):881-885. 20. DiSilvio Jr F, Foyil S, Schiffman B, Bernstein M, Summers H, Lack WD: Long bone union accurately predicted by cortical bridging within 4 months. JBJS Open Access 2018, 3(4). 21. Van Bergen SH, Van Lieshout EMM, Verhofstad MHJ, Den Hartog D: Recovery and functional outcome after radial nerve palsy in adults with a humeral shaft fracture: a multicenter prospective case series. JSES Int 2023, 7(3):516-522. 22. Basakci Calik B, Demir P, Gur Kabul E, Caglayan BC, Keskin A, Karasu U: Validity and Reliability of the Turkish Version of the DASH-TR Questionnaire in Rheumatoid Arthritis Patients, Based on Rasch Analysis. Int J Rheum Dis 2022, 25(8):851-860. 23. Düger T, Yakut E, Öksüz Ç, Yörükan S, Bilgütay BS, Ayhan Kuru C, Leblebicioglu G, Kayihan H, Kirdi N, Yakut Y et al: Reliability and validity of the Turkish version of the disabilities of the arm, shoulder and hand (DASH) questionnaire. Fizyoterapi Rehabilitasyon 2006, 17:99-107. 24. Celik D: Psychometric properties of the Mayo Elbow Performance Score. Rheumatol Int 2015, 35(6):1015-1020. 25. Kirin I, Jurisic D, Grebic D, Nadalin S: The advantages of humeral anteromedial plate osteosynthesis in the middle third shaft fractures. Wien Klin Wochenschr 2011, 123(3-4):83-87. 26. Livani B, Belangero W, Medina G, Pimenta C, Zogaib R, Mongon M: Anterior plating as a surgical alternative in the treatment of humeral shaft non-union. Int Orthop 2010, 34(7):1025-1031. 27. VERGA M, DI CAPRIO AP, BOCCHIOTTI MA, BATTISTELLA F, BRUSCHI S, PETROLATI M: Delayed Treatment of Persistent Radial Nerve Paralysis Associated with Fractures of the Middle Third of Humerus: Review and Evaluation of the Long-Term Results of 52 Cases. Journal of Hand Surgery (European Volume) 2007, 32(5):529-533. 28. Wright TW, Glowczewskie F, Jr., Cowin D, Wheeler DL: Radial nerve excursion and strain at the elbow and wrist associated with upper-extremity motion. J Hand Surg Am 2005, 30(5):990-996. 29. Suwannaphisit S, Aonsong W, Suwanno P, Chuaychoosakoon C: Location of the radial nerve along the humeral shaft between the prone and lateral decubitus positions at different elbow positions. Sci Page 8/12 Rep 2021, 11(1):17215. 30. Wilgis EF, Murphy R: The significance of longitudinal excursion in peripheral nerves. Hand Clin 1986, 2(4):761-766. 31. Warrender WJ, Oppenheimer S, Abboud JA: Nerve monitoring during proximal humeral fracture fixation: what have we learned? Clin Orthop Relat Res 2011, 469(9):2631-2637. 32. Chen WA, Luo TD, Wigton MD, Li Z: Anatomical Factors Contributing to Radial Nerve Excursion at the Brachium: A Cadaveric Study. J Hand Surg Am 2018, 43(3):288.e281-288.e287. 33. Chamseddine AH, Abdallah A, Zein H, Taha A: Transfracture medial transposition of the radial nerve associated with plate fixation of the humerus. Int Orthop 2017, 41(7):1463-1470. 34. Nowak LL, Dehghan N, McKee MD, Schemitsch EH: Plate fixation for management of humerus fractures. Injury 2018, 49 Suppl 1:S33-s38. 35. van de Wall BJM, Ganzert C, Theus C, van Leeuwen RJH, Link BC, Babst R, Beeres FJP: Results of plate fixation for humerus fractures in a large single-center cohort. Arch Orthop Trauma Surg 2020, 140(10):1311-1318. 36. Nicolaci G, Maes V, Lollino N, Putzeys G: How to treat proximal and middle one-third humeral shaft fractures: the role of helical plates. Musculoskelet Surg 2023, 107(2):231-238. 37. Tan JC, Kagda FH, Murphy D, Thambiah JS, Khong KS: Minimally invasive helical plating for shaft of humerus fractures: technique and outcome. Open Orthop J 2012, 6:184-188. Tables Table-1. Summary of the patient groups. Page 9/12 Anteromedial (n = 15) Lateral (n = 16) p-value Age (mean ± SD) 43.47 ± 12.11 42.94 ± 12.56 0.906 BMI*8 (mean ± SD) 22.73 ± 2.89 23.69 ± 4.55 0.495 Surgery Time (mean ± SD) 97.87 ± 12.91 112.88 ± 13.33 0.003 Gender (n%) Male 8 (53.3) 10 (62.5) 0.605 Female 7 (46.7) 6 (37.5) A1 3 (20.0) 2 (12.5) A2 4 (26.7) 3 (18.8) A3 2 (13.3) 5 (25.0) B1 4 (26.7) 4 (25.0) C1 2 (13.3) 3 (18.8) No 13 (86.7) 15 (93.8) Yes 2 (13.3) 1 (6.3) Traffic injury 9 (60.0) 6 (37.5) Fall 4 (26.7) 8 (50.0) Beat 2 (13.3) 1 (6.3) AO Classification (n%) Open Fracture (n%) Trauma Etiology (n%) 0.895 0.600 0.422 * Body mass index Table-2. Nerve recovery times and DASH scores of the groups. Anteromedial Lateral (n = 15) (n = 16) Nerve recovery time (Mean ± SD weeks) 23.87 ± 4.01 35.00 ± 8.15 < 0.001 DASH score 13.13 ± 2.16 15.38 ± 2.77 0.019 MAYO score 90(76–95) 90(78–95) 0,711 MRC muscle power 4(3–5) 4(4–5) 0,984 Figures Page 10/12 p-value Figure 1 Legend not included with this version. Page 11/12 Figure 2 Legend not included with this version. Page 12/12