“Supercharge” Nerve Transfer to Enhance Motor Recovery

“Supercharge” Nerve Transfer to Enhance Motor Recovery

METHODS Table 1. Mean Scores for Surgical (SMPA) vs. Non-Surgical Subjects Preoperative 1-Year Postoperative 2-Year Postoperative 3-Year Postoperati...

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METHODS

Table 1. Mean Scores for Surgical (SMPA) vs. Non-Surgical Subjects Preoperative

1-Year Postoperative 2-Year Postoperative 3-Year Postoperative

MHQ Scales1

SMPA

Non-SMPA

SMPA

Non-SMPA

SMPA

Non-SMPA

SMPA

Non-SMPA

Function

37 (22) 58 (19)**

62 (23)

59 (24)

62 (19)

58 (22)

59 (19)

58 (21)

ADL

34 (26) 59 (24)**

55 (30)

60 (26)

58 (29)

61 (25)

55 (27)

61 (27)

Work

41 (22) 59 (23)**

47 (29)

61 (26)

54 (27)

61 (26)

51 (28)

61 (27)

Pain

49 (26)

36 (25)*

34 (25)

36 (26)

36 (25)

32 (25)

38 (26)

31 (24)

Aesthetics

33 (22) 47 (24)**

68 (23)

52 (23)

66 (23)

53 (21)

60 (21)

54 (20)

Satisfaction

27 (20) 47 (25)**

64 (26)

48 (27)

61 (27)

51 (25)

55 (25)

53 (25)

Overall Score

37 (17) 56 (19)**

60 (22)

57 (21)

61 (21)

59 (20)

57 (20)

59 (21)

AIMS2 Scales2 Physical

4.0 (2.4) 2.5 (1.9)** 3.4 (2.4) 2.4 (1.9) 3.3 (2.2) 2.5 (2.0) 3.4 (2.3) 2.6 (2.2)

Affect

4.2 (1.9) 3.1 (1.8)** 3.6 (1.9) 2.8 (1.6) 3.7 (1.8) 2.9 (1.7) 3.7 (2.3) 2.7 (1.6)

Symptom

5.7 (2.8) 4.3 (2.4)* 4.9 (2.7) 4.0 (2.5) 4.6 (2.4) 3.9 (2.3) 5.0 (2.3) 4.0 (2.5)

Social interaction 4.1 (2.0) 3.6 (1.4)* 3.9 (2.0) 3.6 (1.4) 4.1 (2.1) 3.7 (1.3) 4.1 (2.1) 3.5 (1.6) Objective Measurements Grip Strength (kg) Key (lateral) pinch (kg) 2-point (tip) pinch (kg) Three-jaw (palmar) pinch (kg) Jebson-Taylor (s)3

5.4 (5.2) 8.6 (7.4)* 6.1 (4.5) 10.3 (7.8) 6.1 (4.4) 10.6 (7.5) 6.0 (4.2) 9.7 (5.9) 3.5 (2.2) 4.0 (1.8)

3.1 (1.8) 4.1 (2.0) 3.2 (1.9) 3.7 (1.9) 3.0 (2.0) 3.4 (1.8)

2.5 (1.6) 3.1 (1.5)* 2.6 (1.6) 3.1 (1.7) 2.4 (1.5) 2.9 (1.5) 2.2 (1.4) 2.7 (1.3) 2.5 (1.5) 3.2 (1.4)* 2.6 (1.5) 3.2 (1.4) 2.5 (1.4) 3.2 (1.5) 2.4 (1.5) 2.7 (1.2)

Thirty-nine Lewis rats were randomized into three groups. In all groups, the tibial nerve was transected and repaired in one of three ways. Group 1 was repaired with a 10 mm autograft (representing a partial injury) complemented by a SETS nerve transfer using the peroneal nerve. Group 2 was repaired with a 10 mm autograft only (partial injury only). Group 3 was repaired with SETS peroneal nerve transfer alone and the tibial stumps were capped to prevent regeneration across the gap, serving as control. Nerve histomorphometry, retrograde labeling, muscle mass analysis, and muscle force testing were performed. Data was analyzed by NewmanKeuls testing and significance was determined as p<0.05.

RESULTS Nerve histomorphometry of the distal tibial nerve showed significantly (p<0.03) increased myelinated axonal counts in Group 1 (5659±3803) as compared to Group 2 (2904±1752) and Group 3 (2400±850) at 5 and 8 weeks. Retrograde labeling at 8 weeks confirmed increased motor reinnervation in the distal tibial stump. Functional recovery was evaluated with muscle force testing at 8 weeks, which revealed a significant increase in force (p<0.05) in the “Supercharge” group (Group 1) in comparison to the partial injury group (Group 2).

SUMMARY POINTS ∙

55 (27) 43 (12)**

44 (15)

41 (12)

Ulnar Drift3

37 (15)

13 (11)

Extensor Lag3 MCP Arc of Motion PIP Arc of Motion

65 (23) 47 (18)**

28 (15)

20 (15) 37 (18)** 56 (27) 70 (22)**

35 (15)

43 (11)

39 (10)

44 (13)

40 (12)

34 (15)

14 (9)

33 (16)

14 (11)

34 (17)

49 (21)

25 (14)

48 (23)

29 (15)

53 (21)

30 (16)

33 (19)

33 (17)

33 (20)

30 (14)

29 (16)

67 (24)

71 (19)

66 (25)

67 (22)

64 (26)

67 (21)

Abbreviations: AIMS2, Arthritis Impact Measurement Scales 2, ADL, activities of daily living; SMPA, Silicone Metacarpophalangeal Joint Arthroplasty. Cell values are means (SD). 1 Higher scores correspond to better outcomes, except for pain where higher scores correspond to greater pain. 2 For all AIMS2 subscales, higher scores correspond to worse outcome. 3 Higher values correspond to worse outcome. * P < 0.05 and ** P < 0.001 for between group difference at baseline.

∙ ∙

Complementing a regenerating partially injured nerve with a SETS nerve transfer resulted in superior myelinated axonal regeneration as determined by histomorphometry. SETS enhanced motor recovery in the partial injury model as evidenced by a significant increase in muscle force measurements. Our findings may have a significant clinical application particularly in cases where prolonged regeneration across long distances is anticipated and may yield suboptimal recovery.

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“Supercharge” Nerve Transfer to Enhance Motor Recovery

Figure 1. Experimental groups

Not a clinical study ♦ Scott J. Farber, MD 4JNPOF(MBVT .% :JOH:BO .% 1I% %BOJFM)VOUFS 3" 1IJMJQ++PIOTPO 1I% 4VTBO&.BDLJOOPO .%

HYPOTHESIS The use of a “Supercharge” end-to-side nerve transfer (SETS) will enhance functional recovery in situations of an incomplete nerve injury. SETS nerve transfer provides additional axons for early reinnervation of target muscle to prevent atrophy and fibrosis while axons from the injured nerve continue to regenerate.

4

Figure 2. Myelinated Fiber Counts at 5 and 8 weeks

♦ Speaker has nothing of financial value to disclose