Mapping Recovery: The RADAR Scale, Born From a Clinical Round

Abstract

Objective

To introduce a novel, patient-centered assessment tool, the RADAR (Reach, Activities, Dexterity, Awareness, Role) scale, designed to quantify functional recovery and facilitate communication in patients with nerve injuries, particularly when functional improvement differs from electrophysiological data.

Design

This proof-of-concept study details the development and retrospective application of a new assessment scale derived from a single case observation.

Setting

An inpatient ward at an orthopedic center.

Participants

A 73-year-old woman who developed complete radial nerve palsy after a humeral shaft fracture.

Interventions

The patient underwent open reduction and internal fixation with radial nerve neurolysis, followed by a 7-month rehabilitation program.

Main Outcome Measures

The RADAR scale, a 10-item, 50-point tool assessing functional recovery, was retrospectively applied. Scores were compared with serial electromyogram reports of motor nerve amplitude.

Results

The patient’s total RADAR score progressively improved from 0 preoperatively to 50 at 28 weeks, closely tracking her observed functional gains. In contrast, electromyogram data showed minimal improvement, with motor nerve amplitude remaining far below normal values, demonstrating a stark function-data dissociation.

Conclusions

The RADAR scale can effectively quantify patient-centered functional progress that may be overlooked by standard electrophysiological tests. As a simple tool integrating assessment with shared decision making, it holds potential to improve communication and humanize care in nerve injury rehabilitation. Its validity and reliability warrant investigation in larger prospective studies.

“Doctor, my hand feels much better—I can comb my hair and hold a cup. Why does this report still say my nerve damage is severe?” This question from a 73-year-old patient exemplifies a universal clinical dilemma: conflicts between objective electrophysiological data and a patient’s lived functional experience. This phenomenon of “function-data dissociation” is common in nerve recovery, particularly in cases of radial nerve palsy complicating a humeral shaft fracture—an injury with an incidence of around 10%.¹ Its uncertain healing trajectory not only tests a clinician’s experience but can also profoundly affect a patient’s confidence in their rehabilitation. This case prompted the development of the RADAR scale, a new clinical instrument more attuned to the patient’s functional reality.

Methods

This study was approved by the Institutional Review Board of Chengdu Orthopaedic Hospital (CMEC-2025-0811), and written informed consent was obtained from the patient prior to her participation.

A healthy 73-year-old woman sustained a right humeral shaft fracture after a fall. On admission, she presented with a classic “wrist drop,” complete inability to extend her wrist and fingers, and sensory loss over the dorsal forearm, and was diagnosed with complete radial nerve palsy. Because of the high risk of nerve entrapment, the patient underwent immediate surgical exploration without preoperative electromyogram (EMG).

Intraoperatively, the nerve, although in continuity, was found to be severely compressed by a sharp fracture fragment, appearing hyperemic and edematous with a frayed myelin sheath. A 7-cm neurolysis was performed until the nerve could glide freely.

Immediately after surgery, the patient began an active and passive rehabilitation program. This program consisted of self-directed sessions, each lasting approximately 30 minutes, which the patient was encouraged to perform multiple times daily as tolerated. The regimen focused on active and passive range-of-motion exercises for the wrist and hand, including functional tasks such as repeatedly grasping a tennis ball to improve grip strength and fine motor control.

After obtaining written informed consent, the patient was followed for 7 months. The observed dissociation between her functional recovery and objective electrophysiological data prompted the development of a new assessment tool. The case highlights the clinical need for a new tool that can integrate the strengths of existing instruments (eg, MRC scale, Brien score,² DASH questionnaire³) and include a module for clinician-patient communication.

We therefore developed the Radial Nerve Functional Disability and Recovery (RADAR) scale. The acronym “RADAR” maps a clear path of rehabilitation:

• R – Reach: Assesses the recovery of fundamental movements such as wrist and finger extension.

• A – Activities: Evaluates the ability to perform core activities of daily living, such as combing one’s hair or drinking from a cup.

• D – Dexterity: Measures higher-level tasks requiring both strength and coordination, such as gripping a bottle or pinching a coin.

• A – Awareness: Tracks the return of sensation and the reduction of neuropathic pain.

• R – Role: Gauges the patient’s independence and return to their familial and social roles.

A core innovation of the scale is its integrated shared decision making module, designed to guide the clinician in translating a quantitative score into a meaningful dialogue with the patient to collaboratively review progress and set tangible functional goals. The complete scale is detailed in supplemental appendix S1. The RADAR scale was retrospectively applied to this case to quantify the patient’s recovery journey.

To establish an objective, physiological benchmark against which functional recovery could be compared, serial EMG was employed as the reference standard in this study. The primary metric for comparison was the negative peak amplitude (in millivolts) of the motor nerve conduction study for the radial nerve, which reflects axonal integrity. This specific electrophysiological data point was chosen to create a direct contrast with the patient-centered functional outcomes captured by the RADAR scale, thereby allowing for a clear illustration of the function-data dissociation phenomenon.

Results

The patient’s functional recovery was remarkable. In the early postoperative period (wk 1-4), she began to regain thumb and finger function, evidenced by her ability to abduct her thumb and grip a piece of paper, although wrist drop persisted. A key breakthrough occurred at week 12, when she achieved antigravity wrist extension for the first time and could perform more coordinated tasks, such as unscrewing a bottle cap. Her grip strength, fine motor skills, and independence in daily activities continued to improve steadily, and by week 28, her function had returned to its preinjury level, allowing her to fully resume her normal life.

We transformed this narrative recovery journey into a quantifiable trajectory using the RADAR scale, as shown in table 1. The patient’s total score steadily progressed from 0 preoperatively to 50 at 28 weeks.

Table 1.

Quantitative assessment of this patient’s recovery journey using the RADAR scale.

Dimension	Assessment Item	Preop	1 Wk Postop	4 Wk Postop	8 Wk Postop	12 Wk Postop	20 Wk Postop	28 Wk Postop
R	1. Wrist extension	0	0	0	3	4	5	5
	2. Thumb extension	0	2	3	4	4	5	5
	3. Finger extension	0	2	3	4	4	5	5
A	4. Upper limb coordination	0	1	2	3	4	4	5
	5. Hand-to-mouth coordination	0	1	2	3	4	4	5
D	6. Power grip	0	0	2	3	4	5	5
	7. Precision pinch	0	2	3	4	4	5	5
A	8. Sensation	0	2	3	3	4	4	5
	9. Pain	0	2	3	5	5	5	5
R	10. Overall self-care independence	0	1	2	3	4	5	5
Total score	(Max score: 50)	0	13	21	29	39	48	50

The table presents a quantitative summary of the patient’s recovery, as measured by the RADAR scale at various time points post operation.

This substantial functional progress, however, stood in stark contrast to her serial EMG reports, which for months continued to show “severe demyelination with concurrent axonal damage” and minimal improvement in motor nerve amplitude. This conflict between technical metrics and the patient’s lived experience caused her psychological distress and created communication challenges. To visually represent this central phenomenon of function-data dissociation, we plotted the total RADAR score and a key EMG metric—the negative peak amplitude of the motor nerve—on the same timeline (figure 1).

Fig 1.

Comparison of functional recovery (RADAR score) and electrophysiological data (motor nerve amplitude). The solid blue line represents the RADAR total score (right y-axis, 0-50), which follows a rapid S-shaped curve, reaching 48 of 50 by week 20. The dashed orange line indicates the motor nerve negative peak amplitude of the affected radial nerve (left y-axis, mV), which shows slow, gradual improvement, reaching only 1.24 mV by week 28—far below the contralateral average of 5.1 mV (dashed gray line). The graph strikingly reveals the significant dissociation between functional recovery and this singular electrophysiological measure.

Discussion

Figure 1 visualizes the dissociation between the patient’s swift functional improvement, captured by the RADAR score, and the slow progress of nerve repair, indicated by the flat EMG amplitude curve. This divergence highlights that functional recovery is a complex process involving mechanisms such as cortical plasticity and neuromuscular compensation, which are not captured by electrophysiology alone.⁴

The primary motivation for developing the RADAR scale was not to replace any existing gold-standard assessment, but rather to solve a specific clinical pain point. When a patient hits a recovery plateau, and objective tests offer no positive signals, this tool can successfully capture meaningful functional progress. It provides a solid evidence base for clinicians to maintain the rehabilitation plan and to continually encourage the patient. We envision it as a practical and efficient adjunctive tool in a fast-paced clinical setting. Its core value lies in its dual function. It provides a common language for both clinicians and patients, translating complex clinical findings into understandable, measurable, and shared goals, and it helps both parties clearly track progress, collaboratively planning the focus of the next phase of rehabilitation.

Study limitations

The main limitation of this study is that the RADAR scale originated from a single case and remains at the proof-of-concept stage. Its reliability, validity, and responsiveness must be rigorously validated in future, larger-scale prospective studies. Furthermore, to ensure scoring consistency, we recommend developing more specific operational guidance for key items before wider implementation. However, the value of this report lies not only in proposing a new scale but in illustrating a research paradigm central to clinical progress: how deep engagement with a single patient’s problem can spark a universally applicable, patient-centered solution.

Conclusions

This case reinforces a core clinical principle: in assessing nerve recovery, patient-reported functional improvement should be placed in a position equal to, and at times even more important than, objective electrophysiological data, especially when the 2 diverge. The RADAR scale demonstrates the immense potential of a simple tool to quantify functional progress, facilitate clinician-patient communication, and foster shared decision making. We believe that developing and applying such patient-centered instruments is a critical step toward advancing a more effective and more humanistic model of care.

Disclosure

The investigators have no financial or nonfinancial disclosures to make in relation to this project.