Nail Bed Injury Repair: Nail Plate Replacement Versus Non-replacement

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Any views and opinions expressed are those of the author(s) and/or participants and do not necessarily reflect the views, policy, or position of ePlasty or HMP Global, their employees, and affiliates.

The nail plate plays an important role not only in terms of cosmesis of the hand but also in its function. Injuries to the nail bed of the fingertip are among the most common injuries to the hand, many of which do not come to clinical attention. These injuries often present with associated distal phalanx fractures, nail plate disruption, matrix laceration, and partial or complete fingertip amputation.¹ The nail plate helps to protect the nail bed and exert pressure against the pulp, which improves sensory perception of fine touch and sterognosis.^2-5 The nail plate also serves as an extension of the pincer grasp and aids in the manipulation of fine objects. Historically, patients who have sustained a nail bed injury have been treated with removal of the overlying nail plate followed by repair of the nail bed injury with fine absorbable sutures. The nail plate, or a nail plate substitute, is then replaced under the eponychial fold and sutured into place.^6-8 The rationale for replacement of the nail plate is that it acts as a biological dressing with the function to shape the nail bed, prevent adhesions of the nail fold, splint any associated fractures, decrease post-procedural pain, and improve tactile sensation during the healing period.⁹ Many studies claim that replacement of the nail plate prevents synechiae between the eponychial fold and nail bed that could prevent nail regrowth. To our knowledge, no study has validated this assertion.^9-11 The replacement of the nail plate seems to be largely based on expert opinion with a paucity of clear evidence supporting its practice. Moreover, studies have suggested that the replacement of the nail plate may be associated with increased risk of complications, including post-procedural infection and damage to the germinal matrix.¹¹ This underpowered retrospective study was performed in a pediatric population and emphasized the need for a randomized controlled study investigating patient outcomes regarding nail plate replacement versus non-replacement in nail bed injuries.

There is a paucity of studies directly assessing the effects of not replacing the nail plate after nail bed repair. O'Shaughnessy et al compared 10 patients who underwent nail plate replacement after nail bed injury repair with 54 patients for whom the nail plate was not replaced³ and found no statistically significant difference in terms of rate or regrowth or appearance of the nail. This study did not specify if a nail plate substitute was used, and the decision to replace versus not replace the nail plate was based on the severity of the injury. Appearance grading was also not clearly defined. Zook et al compared replacement of the nail plate with a nail plate substitute and showed a non-statistically significant trend toward better outcomes when the original nail plate was used.⁸ However, in this and similar studies, treatment "without replacement" of the nail plate was defined as those performed with a nail plate substitute inserted under the nail fold. Gu et al performed a retrospective analysis of outcomes in nail bed injuries and concluded that careful suture and replacement of the nail plate to the nail fold was important for good cosmetic and functional results.¹² Their study, however, was primarily comparing nail trephination to nail extraction followed by nail plate replacement and did not look at results of nail bed injuries without nail plate (or nail plate substitute) replacement.

The primary purpose of our prospective, randomized, controlled study was to determine whether patient outcomes in terms of nail growth and nail cosmesis were impacted by nail plate replacement versus non-replacement following nail bed injury repair in an adult population. As secondary outcomes we also reported on patient pain and patient self-reported perception of nail cosmesis. To our knowledge this is the first prospective study addressing these questions in an adult population.

This was an Institutional Review Board–approved prospective, randomized controlled study. All adults 18 years old or older who sustained a nail bed injury and reported to the emergency department at University Hospital in Newark New Jersey were eligible for participation. Patients were enrolled from 2016 until 2021. Exclusion criteria included patients younger than 18 years old, prior fingernail injury, presence of any hand infection, unrepairable nail bed injuries, or requirement of hardware fixation for associated hand injury. Once a patient was deemed a candidate and the patient voluntarily consented to participate in the study, the patient was randomized to 1 of 2 groups: (1) nail bed injury repair with nail plate or nail plate substitute replacement or (2) nail bed injury repair without replacement of the nail plate. Randomization was performed by block randomization in groups of 2, 4, and 6.

All patients underwent repair of the nail bed in the same fashion. Any remaining adhered nail plate was first removed. If the nail plate was salvageable, it was sterilized in a 50-50 mixture of betadine and 0.9% normal saline. The nail bed injury was then cleaned and irrigated with normal saline. Fine 5-0 chromic gut absorbable suture was then used to repair the nail bed. Following repair of the nail bed, group 1 patients underwent nail plate replacement with the original sterilized nail plate whenever possible. If the original nail plate was not available or not appropriate for use, a nail substitute was created using sterilized xeroform foil wrapping. The nail plate or nail plate substitute was placed over the nail bed and under the nail fold. It was then anchored to the nail using 4-0 chomic gut absorbable suture at the edges of the germinal matrix to fix the nail plate or nail plate substitute in place. Group 2 patients underwent an identical nail bed repair; however, no replacement of the nail plate or nail plate substitute was performed. Wounds were then dressed with xeroform, gauze, and a soft compressive wrap.

Patients were to follow up at regularly scheduled visits for assessment. At the final follow-up visit greater than 4 months from injury, primary and secondary outcomes were measured. Patients were assessed for whether the nail plate regrew or whether synechiae between the eponychial fold and the nail bed had prevented regrowth. A picture of the involved nail and contralateral nail were taken at the time of follow-up to evaluate cosmesis based upon Zook grading, a validated method of assessing cosmesis in patients with nail bed injury.⁸ A blinded investigator, an orthopedic hand resident and attending surgeon other than the principal investigator, then assessed cosmesis based on the Zook classification system of the final nail regrowth.⁸ Secondary outcomes were also recorded at this time. Patients were asked if they had any pain associated with the injured digit, if that pain limited their daily activities, and to subjectively rate the cosmetic quality of their nail regrowth as excellent, good, poor, or very poor.

Utilizing previously published data^3,8 for a power analysis, with a power of 0.8, we determined that we would need to enroll approximately 73 patients per treatment group in order to demonstrate a difference in cosmesis and postoperative morbidity between the 2 groups.

Primary outcomes were nail growth by 6 months post-injury and cosmesis of the nail based on Zook classification. Secondary outcomes were pain, limitation of work or daily activities, and subjective patient assessment of cosmesis. Secondary outcomes were assessed via phone interview. Categorical data was analyzed using chi-square and Fisher exact tests while means were assessed using t tests. Statistical analysis was performed using SAS Enterprise Guide 9.4. Statistical significance was set at P < .05.

Fifty participants were consented and enrolled in this prospective study. Average age was 43.9 ± 11.5 years. Thirty-eight (76%) participants were male and 12 (24%) were female. Twenty-seven patients (54%) had left-sided injuries, while 23 (47%) were right-sided. Injuries to the digits were as follows: 11 thumb (22%), 15 index (30%), 13 long (26%), 9 ring (18%), 2 small (4%). Twenty-four (48%) participants were randomized to the replacement group and 26 (52%) to the non-replacement group. Demographics of the treatment groups can be seen in Table 1.

Twenty-eight (56%) patients were seen for follow-up greater than 6 months after their injury; 17 (70.8%) from the replacement group and 11 (42.3%) from the non-replacement group. Neither group was more likely to return to clinic for follow-up (RR = 1.67, 95% CI 1.00-2.81, P = .05). Of the cohort that followed up, there was no significant difference between average age, gender, or laterality between the 2 treatment groups. However, there was a significant difference in the distribution of the involved digits (Table 2). All participants who followed up across both treatment groups had nail growth at their last encounter (RR = 1.00, 95% CI 1.00-1.00, P = 1.00).

Twenty-three (46%) patients followed up by phone call after the nail had fully regrown; 14 from the replacement group and 9 from the non-replacement group. Neither group was more likely to follow up (RR = 1.78, 95% CI 0.98-3.23, P = .06) and there was no significant difference in average age, gender, laterality, or distribution of the involved digits (Table 3). Only 1 patient in the replacement group and none in the non-replacement group reported any limitation in ability to perform work or daily tasks due to their nail bed injury (RR = 1.08, 95% CI 0.93-1.25, P = 1.00). Assessment of secondary outcomes revealed lingering pain in 4 patients in the replacement group, while only 1 in the non-replacement group reported the same (RR = 1.24, 95% CI 0.83-1.86, P = .61). With regard to patient subjective visual assessment of their nail, 13 of the 14 patients in the replacement group rated their nail as either excellent or good as compared with other digits, while 1 rated their nail as either fair or poor. Of the non-replacement group, all 9 patients rated their nail as excellent or good. There was no statistical difference between the treatment groups and subjective nail assessment (RR = 1.08, 0.93-1.25, P = 1.00).

Eighteen (36%) patients were reached for follow-up after the nail had fully regrown for visual assessment by the Zook criteria,12 (66.7%) in the replacement group and 6 (33.3%) in the non-replacement group, and neither group was more likely to return for follow-up for this assessment (RR = 2.17, 95% CI 0.97-4.86, P = .06). There was no statistical difference between these groups with regard to demographic data with the exception of distribution of the involved digit (P = .03) (Table 4). Of the 15 patients in the replacement group assessed by the Zook criteria, 3 patients were determined to each have excellent, very good, and good cosmesis, while 1 was rated as fair and 2 were poor. Of the 6 in the non-replacement group, 5 were excellent and 1 was very good. This assessment revealed no statistical difference between the treatment groups on cosmesis of the nail (P = .19). When comparing assessment by the Zook criteria with subjective patient-reported cosmesis, there was no statistical difference (RR = 1.5, 95% CI 0.67-3.34, P = .167).

Nail bed injuries are among the most common injuries of the hand. To our knowledge there is no prospective randomized controlled study comparing the outcomes of nail bed injuries in adults when the nail plate is replaced versus when it is not replaced. With a lack of clear evidence in the literature, the practice of replacing the nail plate seems to be largely based on expert opinion. Historically, after a nail bed is repaired, the nail plate is replaced and secured in place with suture.^6-8 Some clinicians advocate that replacement of the nail plate prevents synechiae between the eponychial fold and nail bed which could prevent nail regrowth.^9-11 However, there is no study that investigates this claim. In our limited study, there is no evidence suggesting replacement or non-replacement of the nail plate has any effect on regrowth of the nail plate.

The main purpose of this study was to assess if the cosmesis and regrowth of the nail were affected by replacing versus not replacing the nail plate after nail bed repair. Our results suggest that replacement of the nail plate (or nail plate substitute) after nail bed repair does not change patient outcomes in terms of nail growth, cosmesis, or patient satisfaction with repair.

All patients who followed up had nail regrowth whether or not the nail plate was replaced after nail bed repair. There was no statistical difference between groups in terms of the number of patients who followed up for each group. This could indicate that patients were generally satisfied with their result regardless of treatment and did not feel the need to follow up. There was no statistical difference between treatment groups in terms of cosmesis as judged by the Zook classification system. There was also no statistical difference between subjective nail assessment performed by the patient compared with our visual assessment using the Zook criteria on cosmesis. This implies that a satisfactory result is obtained regardless of whether a nail plate is replaced after appropriate nail bed repair.

Only 1 patient in our cohort reported limitation in their ability to perform work or daily tasks after their nail bed injury was repaired. This patient had been randomized to the nail bed replacement arm of our study. Given the low number of patients in our study, no conclusion can be drawn on the clinical significance of this finding. Five patients in our cohort endorsed lingering pain from their nail bed injury at final follow-up, 4 of which were in the nail plate replacement group and 1 of which was in the non-replacement group. These results were not statistically significant. It is possible that patients with continued pain or disability sustained a more severe initial injury or a crush type injury which led to their continued symptoms. However, since we did not collect data on the mechanism of injury for this study, we cannot comment on whether the continued disability was a result of the treatment or the consequence of the injury itself.

Those patients allocated to the non-replacement group showed a trend toward better outcomes in terms of cosmesis, though this was not statistically significant. This is contradictory to previously held opinions on the importance of nail plate replacement on cosmetic outcomes and may indicate that replacing the nail plate carries the unnecessary risks of performing a procedure without adding any clinical benefit. Perhaps if a greater number of patients completed the study, this may have reached significance.

To date, controversy still exists over the proper treatment of nail bed injuries. It is generally agreed that proper nail bed repair is essential for normal nail regrowth and nail adherence, and different repair modalities have proven equally effective.^10,12-14 It has been observed that crush injuries and injuries that result in scaring of the germinal matrix have a higher likelihood of resulting in poor or aberrant nail regrowth.^3,5,8,9 Other studies have evaluated the use of foil, silicone, and non-adherent gauze placed under the nail fold as a nail plate substitute and found no difference in cosmesis and nail when compared with the native nail plate.^8,15 Our study indicates that replacing the nail plate may be associated with increased complications with little cosmesis benefit. This is in line with previous pediatric studies which showed replacement of the nail plate or nail plate substitutes were associated with an increased risk of infection and could subsequently damage the nail bed or lead to osteomyelitis.^1,16 There is also the theoretical added risk of possible germinal matrix damage when suturing the nail plate back in place.

There is a paucity of studies directly assessing the effects of not replacing the nail plate after nail bed repair. O'Shaughnessy et al compared 10 patients who underwent nail plate replacement after nail bed injury repair with 54 patients for whom the nail plate was not replaced and found no statistically significant difference in terms of rate or regrowth or appearance of the nail.³ This study did not specify if a nail plate substitute was used, and the decision to replace versus not replace the nail plate was based on the severity of the injury. Appearance grading was also not clearly defined. Zook et al compared replacement of the nail plate with a nail plate substitute and showed a non–statistically significant trend toward better outcomes when the original nail plate was used.⁸ However, in this and similar studies, treatment "without replacement" of the nail plate was defined as those performed with a nail plate substitute inserted under the nail fold. Gu et al performed a retrospective analysis of outcomes in nail bed injuries and concluded that careful suture and replacement of the nail plate to the nail fold was important for good cosmetic and functional results.¹² Their study, however, was primarily comparing nail trephination to nail extraction followed by nail plate replacement and did not look at results of nail bed injuries without nail plate (or nail plate substitute) replacement.

Despite being a prospective, randomized study there are some significant limitations. First, we had low enrollment rates and a high loss to follow-up of nearly 50%. One explanation may be that nail bed injuries are considered relatively minor injuries and therefore many patients may not have felt the need to follow up if they were satisfied with their outcome. It is also possible that patients elected to not follow up or sought care elsewhere because they were dissatisfied with their outcome. Each treatment group had the same proportion of loss to follow-up, implying that this was not directly influenced by a specific treatment assignment. The study was also underpowered. We enrolled 50 patients total compared with the 73 per group desired based on our power analysis. As previously mentioned, there was a trend toward better outcomes in the non-replacement group; however, this difference was not statistically significant. This could imply no difference in outcomes between treatment pathways; however, we cannot definitively make this statement. We also did not collect data on the severity or cause of the nail bed lacerations. Degree or mechanism of injury may play a role in cosmetic outcome and could thus skew results if allocated disproportionately.¹² Randomizing patients prior to assigning treatment groups should have theoretically mitigated this potential bias.

Based on this limited prospective study, we feel that there is no evidence of clinical benefit to replacing the nail plate following a nail bed repair. Given the limitations presented in this study, however, a definitive recommendation cannot be made without further investigation. We feel that a similarly designed study with better recruitment and follow-up would be appropriately powered to show no difference in outcomes, and perhaps this paper could serve as a nidus for future research.