Clinical Outcomes of Flexor Tenolysis Following Zone 2-3 Flexor Tendon Repair: A Retrospective Review

Abstract

Purpose

Adhesions and finger stiffness are common complications following zone 2 and zone 3 flexor tendon repairs. When active finger flexion recovery has plateaued, flexor tenolysis can be an effective surgical option. However, literature reporting the outcomes of flexor tenolysis is scarce.

Methods

Medical records were reviewed for patients who underwent flexor tenolysis after primary repair over a 10-year period. Clinical outcomes, including active range of motion, total active motion, pain scores, and composite flexion, were assessed after surgery.

Results

68 digits in 31 patients met study criteria. At the 12-week follow-up, total active motion improved considerably from 146.8° to 183.5°, and active range of motion at the proximal interphalangeal joint increased from 46.1° to 60.0°. Composite flexion improved from 2.5 to 1.9 cm from the distal palmar crease. Half of the digits achieved excellent or good outcomes based on the Modified Strickland score. Reoperation was the most common complication. Flexor tendon rupture occurred in 3% of cases.

Conclusions

Flexor tenolysis can be effective for improving motion following tendon repair, particularly in primary procedures and isolated tendon injuries. Revision tenolysis, dual tendon repairs, and associated digital nerve injuries were associated with poorer outcomes.

Clinical relevance

Flexor tenolysis offers meaningful, though modest, improvements in motion for patients with stiffness after zone 2–3 flexor tendon repair, reinforcing its role as a valuable secondary procedure when recovery plateaus. This study further clarifies which patient and injury characteristics predict better or poorer outcomes, helping surgeons counsel patients more accurately and tailor expectations for recovery.

Complications following flexor tendon repairs in the hand are common, with decreased active motion occurring in 4% to 10% of patients.¹ Loss of active finger flexion may occur because of adhesions between the flexor tendons and their fibro-osseous sheath and the underlying proximal phalanx.^2,3 Risk factors for developing adhesions include high-energy trauma, tendon ischemia, prolonged immobilization, and bulky tendon repairs.² Additionally, concurrent digital nerve damage can disrupt proprioceptive feedback, Golgi tendon organs, and muscle spindle afferents.^4,5 As a result, there is reduced finger motion control and less spontaneous motion, which permits adhesion formation.^4,6

If active motion recovery plateaus after 3–6 months of therapy, flexor tenolysis can be an effective surgical option to increase the active range of motion (AROM) of the finger. Prerequisites for tenolysis include supple joints with near normal passive range of motion, good muscle strength, and motivated patients who embrace postoperative therapy to achieve successful outcomes.^4,6, 7, 8, 9 There is currently a paucity of literature reporting outcomes of flexor tenolysis as a secondary procedure following isolated flexor tendon lacerations. The purpose of this study is to review clinical outcomes and complications in patients who underwent flexor tenolysis to recover AROM after zone 2 and 3 flexor tendon repairs.

Materials and Methods

A retrospective chart review from 2012 to 2022 was performed for patients who underwent flexor tenolysis for inadequate finger flexion following zone 2–3 flexor tendon repair by fellowship-trained hand surgeons at an academic institution. All patients were treated after surgery with early AROM therapy protocols supervised by certified hand therapists. Data were collected before surgery and after surgery at 2, 6, and 12 weeks.

After obtaining Institutional Review Board approval, patients were identified by 2023 Current Procedural Terminology codes 26440 (tenolysis, simple, flexor tendon of the palm or finger) and 26442 (tenolysis, simple, flexor tendon of the palm and finger). Patient records were screened based on inclusion and exclusion criteria. Inclusion criteria required patients had (1) a zone 2 or zone 3 flexor tendon injury because of a laceration mechanism, (2) primary flexor tendon repair, and (3) underwent flexor tenolysis for finger stiffness. Exclusion criteria included patients with (1) flexor tendon injuries in zones 1, 4, and 5, (2) thumbs, (3) concomitant pulley reconstruction, (4) concomitant hand fracture, or (5) finger replantation or revascularization.

Data recorded included patient demographics, comorbidities, procedures performed during the initial flexor tendon repair, and concomitant procedures during the secondary flexor tenolysis. Hand therapist and orthopedic clinic notes were reviewed for active and passive ROM, pain scores, and fingertip to distal palmar crease (DPC) on composite flexion. Pain scores were reported using the visual analog scale-Pain scale. Total active motion (TAM) was calculated by summing the AROM of the metacarpophalangeal, proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints. Functional outcomes were graded on the Modified Strickland, as interpreted in the Table 1.^8,10,11 The Modified Strickland grade was calculated by (PIP + distal interphalangeal active ROM)/175 × 100%.¹² Complications, including reoperation, tendon rupture, infection, and digital nerve injuries, were also recorded.

Table 1.

Modified Strickland Grading for TAM of the Interphalangeal Joints

Grade	Percentage of Normal ROM
Excellent	>75%
Good	50% to 74%
Fair	25% to 49%
Poor	0% to 24%

Two-tailed t tests were used to compare the range of motion (TAM, PIP, and composite flexion) as well as pain scores. Subanalyses were performed to compare flexor tenolysis with and without PIP capsulotomy, primary and revision flexor tenolysis, single tendon to both flexor tendons repaired, and fingers with and without primarily repaired digital nerves. Statistical analysis was performed using Microsoft Excel 16 (Version 2308).

Results

Over a 10-year period, 360 flexor tenolysis procedures were identified. A total of 68 fingers in 31 patients met the inclusion criteria for analysis. The mean time between flexor tendon repair and tenolysis was 50.8 weeks. The mean age was 45.4 years old (range 17–80) with 20 men and 11 women. The right hand was involved in 17/31 patients, and multiple fingers were involved in 7/31 patients. Eleven patients sustained injuries that qualified for workers’ compensation, 14 were active smokers, and 2 had diabetes. Follow-up data were available for 100% of patients at 2 weeks, 91.2% of patients at 6 weeks, and 69.1% of patients at 12 weeks.

Patients had significant improvements in active motion (P < .001) at the PIP joint as well as TAM (P < .001) at 12 weeks after surgery. Active ROM, TAM, and PIP flexion contracture at each of the time points are shown in Table 2. Composite flexion DPC improved from 2.5 cm to 1.9 cm at 12 weeks (P < .05). At 12 weeks post tenolysis, the Modified Strickland scoring formula determined 21.1% digits scored excellent, 28.9% scored good, 42.1% scored fair, and 7.9% scored poor.

Table 2.

Overall Outcomes

	Mean PIP Flexion Contracture	P Value, Compared to Baseline	Mean PIP Active ROM	P Value, Compared to Baseline	TAM	P Value, Compared to Baseline
Pretenolysis baseline	23.0°		46.1°		145.2°
2 wks	22.4°	.19	47.5°	.99	153.6°	.75
6 wks	21.4°	.50	55.2°	.06	162.8°	.02
12 wks	21.5°	.07	60.0°	<.001	179.5°	<.001

At the time of flexor tenolysis, 10 patients had additional procedures, including 7 volar PIP capsulotomies, 3 metacarpophalangeal capsulotomies, and no cases of extensor tenolysis. Digits that underwent flexor tenolysis and volar PIP capsulotomy had preoperative PIP flexion contracture of 54.3° compared to 18.9° for digits undergoing the flexor tenolysis alone (P < .0001). At 12-week follow-up, the volar PIP capsulotomy cohort achieved 35.0° active extension (P = .11). The same cohort experienced mild improvements in TAM (135.0° to 145.0°, P = .26). In contrast, TAM for flexor tenolysis alone improved significantly from 149.8° to 184.3° (P < .01).

Primary versus revision flexor tenolysis was assessed (Table 3). At 12-week follow-up, TAM data were available for 25 of 55 (45.4%) primary cases and 8 of 13 (72.7%) revision cases.

Table 3.

Primary Versus Revision Flexor Tenolysis

		PIP Active ROM				Total Active Motion				VAS-Pain				Distance to DPC (cm)
		Pretenolysis Baseline	2 Wks	6 Wks	12 Wks	Pretenolysis baseline	2 Wks	6 Wks	12 Wks	Pretenolysis baseline	2 Wks	6 Wks	12 Wks	Pretenolysis baseline	2 Wks	6 Wks	12 Wks
Primary tenolysis (n = 55)	Degrees	46.9°	47.6°	59.6°	63°	150.1°	154.6°	170.8°	183.8°	1.44	1.86	1.45	1.15	2.53	2.26	2.31	1.43
	P value, compared to baseline		.81	.01	<.01		.72	.01	<.01		.46	.75	.48		.16	<.01	.09
Revision tenolysis (n = 13)	Degrees	43.1°	47.1°	39.3°	53.1°	122.5°	147.5°	135.6°	166.3°	1.33	4.00	2.83	2.00	2.13	4.00	4.33	3.17
	P value, compared to baseline		.52	.68	.18		.50	.98	.06		.12	.13	.42		.06	.50	.34

Digits with prior single flexor tendon repair (SFTR) versus both flexor tendon repair (BFTR) before flexor tenolysis were reviewed (Table 4). All single flexor tendon repairs were performed on the flexor digitorum profundus. The SFTR cohort had 2 tendon ruptures compared to 9 reoperations in the BFTR cohort (20.9% of fingers), including 8 revision flexor tenolyzes.

Table 4.

Single Versus Both Flexor Tendons

		PIP Active ROM				Total Active Motion				VAS-Pain				Distance to DPC (cm)
		Pretenolysis Baseline	2 Wks	6 Wks	12 Wks	Pretenolysis Baseline	2 Wks	6 Wks	12Wks	Pretenolysis Baseline	2 Wks	6 Wks	12 Wks	Pretenolysis Baseline	2 Wks	6 Wks	12 Wks
Single tendon repair (n = 13)	Degrees	52.1°	60.5°	86.0°	81.8°	163.6°	188.0°	226.3°	214.3°	2.14	3.00	2.13	1.67	2.63	1.67	0.85	1.25
	P value, compared to baseline		.24	.01	.07		.10	.01	.12		.08	.55	1.00		Insufficient data	.04	Insufficient data
Both tendon repair (n = 42)	Degrees	40.5°	41.7°	44.8°	56.6°	132.0°	134.1°	142.5°	174.0°	0.97	2.00	1.93	0.81	2.55	2.61	3.24	2.06
	P value, compared to baseline		.86	.50	.01		.89	.47	.01		.04	<.05	.74		.92	.41	.49

Forty-five digits had prior primary digital nerve repairs before flexor tenolysis (Table 5). The ulnar digital nerve was repaired in seven fingers, the radial digital nerve was repaired in 13 cases, and both radial and ulnar digital nerves were repaired in 25 cases.

Table 5.

With and Without Digital Nerve Repair

		PIP Active ROM				Total Active Motion				VAS-Pain				Distance to DPC (cm)
		Pretenolysis Baseline	2 Wks	6 Wks	12 Wks	Pretenolysis Baseline	2 Wks	6 Wks	12 Wks	Pretenolysis Baseline	2 Wks	6 Wks	12 Wks	Pretenolysis Baseline	2 Wks	6 Ws	12 Wks
No repair (n = 23)	Degrees	54.8°	53.2°	66.0°	56.4°	170.4°	170.0°	181.3°	169.5°	2.00	2.75	1.25	1.64	2.67	1.85	1.67	1.39
	P value, compared to baseline		.31	.26	.22		.30	.34	.14		.51	.58	.60		.18	.19	.38
Single nerve repair (n = 20)	Degrees	37.7°	46.8°	55.7°	59.4°	153.2°	155.8°	187.0°	191.0°	1.80	3.15	2.93	2.00	1.92	1.40	1.00	1.38
	P value, compared to baseline		.13	.03	<.01		.04	.02	.02		.12	.07	.38		.18	.02	.92
Both nerves repaired (n = 25)	Degrees	45.0°	41.8°	45.1°	64.3°	123.1°	127.1°	128.8°	180.0°	0.56	1.60	1.28	0.38	3.14	3.66	4.00	2.33
	P value, compared to baseline		.59	.99	.11		.20	.71	.03		1.00	.34	.36		.09	.02	.01

Complications are enumerated in Table 6. Reoperations following tenolysis occurred on 10 fingers in 8 patients at an average of 4.5 months. The most common procedure was revision flexor tenolysis. Altered digital sensation was reported by eight patients, but no patients had complete sensory loss. As a result of stiffness and months lost to follow-up, one patient elected for a ray amputation. One patient developed a painful digital neuroma, which was excised. Surgical site infection occurred in one patient requiring a surgical debridement, and two patients developed superficial wound dehiscence, which resolved with outpatient wound care.

Table 6.

Complications

Complication	Cases
Reoperation	10
Altered digital sensation	8
Surgical site infection	3
Tendon rupture	2

Discussion

Tendon adhesions following flexor tendon repair can result from multiple etiologies, including trauma to the tendon or overlying sheath, infection, tendon ischemia, and poor tendon repair.¹³ Flexor tenolysis may be an effective surgical intervention to improve AROM in an appropriately indicated patient. Ideal surgical candidates for flexor tenolysis must have pliable soft tissues, good before surgery passive range of motion, healed underlying fractures, and an intact pulley system. High compliance with therapy after surgery is paramount to success.^8,9,14

There is a scarcity of literature to guide patient, therapist, and surgeon expectations following flexor tenolysis of flexor tendon repairs. The present study sought to delineate outcomes of flexor tenolysis following zone 2–3 flexor tendon repair. Our findings align with prior reports showing modest improvements in motion.7, 8, 9 While absolute gains in TAM and composite flexion were comparable to the literature, outcomes in our series were somewhat less favorable as graded by the Modified Strickland score, where only half of our patients achieved an excellent or good outcome.^8,9 However, only 38 cases (55.8%) at 12-week follow-up had sufficient data to calculate the Modified Strickland score at 12-week follow-up, which limits comparability. Compared to other studies, outcome differences may reflect our larger sample size, stricter inclusion criteria, or limited follow-up at 12 weeks, which may underestimate longer-term recovery.

The role of adjunctive volar PIP capsulotomy is less clear. In our series, PIP extension and TAM improved in the early postoperative period, but most fingers lost PIP extension gains at the 12-week follow-up. This finding contrasts with some reports of substantial benefit.^8,9 It is important to consider that capsulotomy was performed at the discretion of the treating surgeon, typically to address a joint contracture in addition to tendon adhesions. Compared to patients with tendon adhesions with full passive ROM who elected for flexor tenolysis, the addition of capsulotomy may not improve final motion and may result in increased scar formation.

Patients who underwent revision flexor tenolysis gained nearly 45° of TAM, but this was not significant. Digits undergoing secondary tenolysis demonstrated worsened overall distance to DPC (2.13 cm to 3.17 cm) and higher pain scores, perhaps because of compounded scarring and decreased tissue compliance. Additionally, higher pain scores may impact vigorous engagement in hand therapy and home exercise programs. To our knowledge, these outcomes for revision flexor tenolysis have not been previously reported and highlight the need to temper expectations.

The number of flexor tendons repaired during the index procedure also influenced outcomes. Digits with BFTR demonstrated significant motion gains following flexor tenolysis. In comparison, SFTR patients demonstrated greater absolute motion improvements compared to the preoperative baseline, but lost significance by 12-week follow-up. The trend of greater motion recovery and final TAM with flexor tenolysis following a single tendon repair, compared to both tendon repairs, echoes Tang’s findings that greater repair bulk within the sheath predisposes the tendon to greater adhesion formation.¹⁵ Tang suggested that leaving FDS unrepaired may reduce the risk of adhesion formation and lead to a greater range of motion.¹⁶

Fingers with concomitant digital nerve injuries had worse pretenolysis TAM. Fingers without prior nerve repair demonstrated a TAM of 170°, compared with 153° in the single nerve group and 123° in the double nerve repair group. Our finding is consistent with prior work by Diehm et al,⁴ suggesting impaired proprioceptive feedback hinders the benefits of post-op rehabilitation.⁴ Despite the worse preoperative TAM, patients with both nerves repaired had greater gains in TAM, going from 123.1° to 180° at the 12-week time point. The same study noted fingers with bilateral digital nerve injuries have more tendon ruptures (0.4% of patients) compared to those without nerve injury (n = 0; P < .05).⁴ Though our study observed a low rate of tendon rupture (3%), it is worth noting that tendon ruptures only occurred in digits that had previously undergone digital nerve repair.

Flexor tenolysis procedures have a high rate of complications, with reoperation being the most common. Thirteen fingers (19.1%) underwent revision flexor tenolysis, and 4 cases additionally received a capsulotomy. Eight patients (11.8%) reported altered digital sensation, though none had complete sensory deficits. Digital nerve injuries following flexor tenolysis have not previously been reported in the literature. Flexor tendon rupture rate was 3% (2 fingers), which is lower than other studies, which range from 5% to 13%.^4,6,9

There are multiple limitations of this study. First, this is a retrospective study with a considerable number of patients lost to follow-up, particularly between the 6-week and 12-week time points. Second, this study was limited to short term follow-up at 12 weeks. It is difficult to speculate what the outcomes may be at 6 months or longer with continued supervised hand therapy and return to activities of daily living. Third, the current study does not include adhesions related to infectious or traumatic crush etiologies or those with concomitant hand fractures. These deeper injuries may involve the volar plate, collateral ligaments, or capsule, which may potentially limit motion improvements with flexor tenolysis.

Flexor tenolysis is a technically challenging surgery for tendon adhesions following flexor tendon repair. The present study found modest improvement in PIP motion and TAM over 12 weeks after flexor tenolysis in patients with prior zone 2–3 flexor tendon repair with or without digital nerve injury. The best improvements were observed in patients undergoing primary tenolysis, those with single tendon repairs, and those with concomitant digital nerve injuries. In contrast, revision tenolysis and those with both tendons repaired demonstrated a reduced TAM following tenolysis. When volar PIP capsulotomy was combined with tenolysis, the surgical gains to reduce the contracture were temporary. Flexor tendon rupture is rare following flexor tenolysis. Although overall improvement in range of motion can be expected, patients should be counseled on the modest improvement in outcome and potential complications.

Conflicts of Interest

The authors have no relevant conflicts of interest that pertain to the research in this article.