Reference:  Jain A, et al. Effectiveness of nail bed repair in children with or without replacing the fingernail: NINJA multicentre randomized clinical trial. Br J Surg. March 2023

Date: May 7, 2024

Guest Skeptic: Dr. Brian Lee is a pediatric emergency medicine attending at the Children’s Hospital of Philadelphia and Assistant Professor of Pediatrics at the Perelman School of Medicine at the University of Pennsylvania.

Dr. Brian Lee

Case: A 5-year-old girl comes to the emergency department (ED) after smashing her finger with a hammer. Her mother, who possesses a strong “do-it-yourself” attitude, was busy constructing a bookshelf for her daughter when the girl grabbed a hammer to help and promptly dropped it on her finger. On your exam, the girl is tearful and has a bloody index finger, and the fingernail is almost nearly avulsed. She is otherwise uninjured. Her mother tells you, “I remember this happening to me when I was younger, and they had to remove my fingernail. Is there any way to save the fingernail?”

Background: Fingertip and nail bed injuries are some of the most common hand injuries in children. These can range from subungual hematomas to lacerations to partial amputations. Fingers and hands are important for performing daily activities, and we want to ensure that these injuries heal appropriately. That includes considerations for function and cosmesis.

Some myths have been perpetuated throughout the years regarding finger injuries. For example, the teaching that if a subungual hematoma is >50% of the nail bed, then the nail should be removed because there is likely an underlying nailbed laceration that needs to be repaired. This is not true because we have learned that if the nail is otherwise intact, we can just trephinate it and be done.[1]

Another practice that we’ve encountered in fingertip injuries where the nail is avulsed is replacing the nail during the repair. Reasons for that practice include protecting the repair, splitting the nail fold, and reducing infection. But there is not really high-level evidence to back up those claims, and some centers have even advocated for not replacing the nail given the challenges of adequately cleaning the native nail. [2]

Suturing nailbeds and suturing avulsed fingernails back on tend to be a bloody mess. This might be the time for the “don’t just do something, stand there” approach [3].

Clinical Question: Is discarding the fingernail during nail bed repair superior to retaining it?

 Reference:  Jain A, et al. Effectiveness of nail bed repair in children with or without replacing the fingernail: NINJA multicentre randomized clinical trial. Br J Surg. March 2023

  • Population: Children less than 16 years of age with nail bed injury to a single finger occurring within 48 hours of presentation believed to require surgical repair
    • Exclusion: Infected injury, underlying nail disease, deformity to the injured finger, amputation, loss of nail bed requiring reconstruction, multiple nail bed injuries
  • Intervention: Fingernail replacement after debridement and suturing of the nail bed or fingernail substitute like foil.
  • Comparison: No fingernail replacement.
  • Outcome:
    • Primary Outcome: Co-primary outcomes of surgical site infection at 7-10 days and cosmetic appearance of the nail using the Oxford Fingernail Appearance Score (OFNAS)
    • Secondary Outcomes: Quality of life based on the EuroQol Five Dimensions (EQ-5D-Y), pain at first dressing change, surgical site infection by 4 months, parent assessment of nail appearance at 4 months, cost difference
  • Trial: Multicentre, pragmatic two-arm parallel-group superiority randomized controlled trial

Authors’ Conclusions: After nail bed repair, discarding the fingernail was associated with similar rates of infection and cosmesis ratings as replacement of the fingernail, but was cost saving.

Quality Checklist for Randomized Clinical Trials:

  1. The study population included or focused on those in the emergency department. No
  2. The patients were adequately randomized. Yes
  3. The randomization process was concealed. No
  4. The patients were analyzed in the groups to which they were randomized. Yes
  5. The study patients were recruited consecutively (i.e. no selection bias). No
  6. The patients in both groups were similar with respect to prognostic factors. Yes
  7. All participants (patients, clinicians, outcome assessors) were unaware of group allocation. No
  8. All groups were treated equally except for the intervention. Unsure
  9. Follow-up was complete (i.e. at least 80% for both groups). Yes
  10. All patient-important outcomes were considered. Yes
  11. The treatment effect was large enough and precise enough to be clinically significant. Yes
  12. Financial conflicts of interest. None.

Results: They recruited 451 children presenting to 20 secondary-care hospitals with 224 allocated to the nail-discarded group and 227 in the nail-replaced group. The average age was approximately 5.9 years, about 54% of participants were male and most injuries were due to crush and avulsion of the nail plate.

Key Results: No difference in the number of surgical-site infections at seven days or cosmetic appearance.

Primary Outcome:

There were fewer surgical-site infections in the group that had the nail discarded compared to the group that had the nail replaced (2 vs. 5) but this was not statistically significant (p=0.218). The children in the nail-discard group did not have higher OFNAS scores as compared to those whose nail was replaced. However, given that parents were included as assessors, a post-hoc analysis of scores given by the parents did show a significant difference (OR- 0.24, 0.06-0.96. p=0.044).

Secondary Outcomes: 

The authors compared parent to assessor OFNAS median scores. There was no difference between the OFNAS scores in the nail-discarded vs. nail-replaced groups in the assessor scores. But they found that the parent scores favored the nail-discarded group (p=0.044). This can be seen in Table S2.

There was no statistically significant difference in pain at first dressing change.

When it came to quality of life, ED-5D-Y scores between the two groups were not significantly different. These values can be found in Table S4.

The mean total healthcare cost was lower in the nail discarded group £75.07 (95% CI; £30.05 to £124.11).

Superiority, Equivalence, Non-Inferiority:

The NINJA trial was a superiority trial.

What’s the difference between Superiority, Equivalence and Non-Inferiority? Let’s take a moment to review these types of studies that are comparing two interventions.

  • A superiority study is looking to demonstrate that one intervention is better than the other. The null hypothesis in a superiority study is that there is no statistical difference between the treatments or interventions. The alternative hypothesis is that there is a statistically significant difference in favor of the new treatment.
  • An equivalence study is looking to see if two interventions are of similar efficacy within a predetermined margin of allowable difference. The null hypothesis of an equivalence study is that there is a difference between the two interventions outside of the margin. The alternative hypothesis is that they are equivalent within that margin.
  • A non-inferiority study is looking to see if a treatment is not acceptably worse than another treatment (often some reference standard) by a predetermined margin. The null hypothesis is that the new treatment is inferior compared to the other treatment by more than the margin. The alternative hypothesis is that the new treatment is non-inferior to the other treatment within the margin.

Does the delineation between all  of these types of trials need to be so sharp? [4] There are examples of where studies are designed as non-inferiority trials but end up demonstrating superiority like the trial that compared diluted apple juice versus electrolyte rehydration solution for rehydration in children with mild gastroenteritis covered in SGEM #158.

Our friend, Justin Morgenstern, of First10EM has a great blog post titled, “You don’t understand non-inferiority trials (and neither do I)

Patient and Public Involvement:

In the methods section, the authors specifically note that patients and the public were involved from the start of the research in developing the pilot study and the final RCT. As patient or family values and preferences are one of the pillars of evidence-based medicine, we are thrilled to see it incorporated into the research design at such an early stage.

This is something we discussed with Dr. Damian Roland in SGEM Xtra: Making Research, Better, Faster, Stronger.

Patients and parents completed a survey to help set the outcomes. There was a patient representative as a trial co-investigator and in the trial management group. They even helped with advice on participation, patient information, and dissemination.

Patient-Oriented Outcomes:

There were fewer surgical site infections in the group that had the fingernail discarded. This did not end up being statistically significant, but still interesting.

The cosmetic outcome was assessed using the OFNAS score. We went back and looked at the initial paper about the OFNAS score where it reported the interrater reliability using kappa.[5] That kappa value was 0.52. This value assesses the agreement between raters. A kappa value between 0.4-0.6 represents only moderate agreement. But even with that limitation, the parents rated the cosmetic outcomes in the nail-discarded group more favorably.


This study was unmasked. The authors did a good job of trying to measure confounders such as type of anesthetic, perioperative antibiotics, surgical prep, dressing, sutures, and operative time. This can be seen in Table S1.

Nevertheless, could there have been other factors not captured in this data? This may be analogous to some of the evidence around laceration care (tap water versus other irrigation, sterile gloves versus regular gloves). The unmasked nature of the intervention may have caused some changes in operative behavior. Maybe due to concern for infection in the nail-discarded group, the surgeons spent a bit more time irrigating or something else? There’s also the caveat that these patients underwent repair by a surgeon, likely in the operating room which is a bit different compared to the chaos of the emergency department.


These were patients recruited from hand surgery units. Around 20% of them underwent general anesthesia and 70% received both general and local anesthesia for repair. There’s probably some practice variability here as many of our listeners are likely repairing these in the emergency department without general anesthesia.

Comment on Authors’ Conclusion Compared to SGEM Conclusion: We agree with the authors’ conclusion.

SGEM Bottom Line: You may not need to replace the child’s fingernail after nail bed repair.

Case Resolution: You assess the integrity of the girl’s affected fingernail and note that it is no longer adhered to the nail bed. X-rays are obtained that demonstrate a small tuft fracture of the finger but no additional fractures. You remove the avulsed fingernail and do not see any additional active bleeding from the affected area. After discussing with the family whether to replace the fingernail, they expressed that they have had a long day and would prefer to just wrap up the finger and go home.

Clinical Application: This superiority study ultimately did not demonstrate statistical superiority. But looking at the results, it seems like the rates of infection, cosmetic outcome, and function were very similar between the two groups. If anything, the infection rate was a bit lower in the group that did not have their fingernail replaced.

This study is yet another example of how sometimes doing less is more. We should still clean and evaluate these finger injuries for any lacerations that need repair and control of bleeding. But if the nail is missing, don’t worry about it too much. If the nail is brought in by the family, not replacing it seems appropriate. It can cut down on time in the emergency department, get the family home faster, and does not seem to be harmful.

What do I tell my patient?  I’m sorry you hurt your finger. Luckily, children tend to heal well. Let’s take an X-ray to see whether or not there is any damage to the bone underneath. It looks like the fingernail is no longer attached. We can discuss whether you would like me to try to re-attach it. Let’s discuss the potential harms and benefits.

Remember to be skeptical of anything you learn, even if you heard it on the Skeptics Guide to Emergency Medicine.


  1. Roser SE, Gellman H. Comparison of nail bed repair versus nail trephination for subungual hematomas in children. J Hand Surg Am. 1999;24(6):1166-1170.
  2. O’Shaughnessy M, McCann J, O’Connor TP, Condon KC. Nail re-growth in fingertip injuries. Ir Med J. 1990;83(4):136-137.
  3. Keijzers G, Cullen L, Egerton-Warburton D, Fatovich DM. Don’t just do something, stand there! The value and art of deliberate clinical inertia. Emerg Med Australas. 2018;30(2):273-278.
  4. Dunn DT, Copas AJ, Brocklehurst P. Superiority and non-inferiority: two sides of the same coin? Trials. 2018;19(1):499.
  5. Jain A, Stokes J, Gardiner MD, et al. The Oxford Finger Nail Appearance Score – a new scoring system for fingernail deformity following paediatric finger tip trauma. J Plast Reconstr Aesthet Surg. 2021;74(1):94-100