Table 3 The included studies, number of patients, age, follow-up time, outcome measures, results and complications

Jain et al. 2020 [22]

FHL + G-flap

15

43.5 years

19.07 months (13–24)

AOFAS, ATRS

AOFAS score: 98.4 SD 2.03 (94–100), preop: 72.07 SD 8.29 (62–83)

ATRS score: 98 SD 1.85 (94–100), preop: 61.73 SD 8.16 (52–70)

No re-ruptures. Serous discharge and delayed wound healing (2), wound infection (1)

Elgohary et al. 2016 [13]

FHL + G-flap

19

47 years

29 months (13–52)

AOFAS

AOFAS score: at 6 months 88.4 (72–96), at 12 months and at last follow-up 94 (76–100), preop: 65 (52–72). Mean time for return to work was 90 days (42–120), and to sport activity (4 patients) it was 147.5 days (90–210). All patients had calf muscle hypotrophy with a mean difference of 0.6 cm in calf circumference (0.3–1.8). All patients were able to perform a single leg heel-rise at the last follow-up

No re-ruptures. Deep infection (1). Skin sloughing, needing a skin graft (1). Hypertrophic scar (1). Superficial infection (3)

Koh et al. 2019 [26]

FHL + G-flap

49

60 years

At least 12 months

AOFAS, VAS, SF-36

AOFAS score: at 3 months 76 (SD 22), at 6 months 83 (SD 18), at 12 months 95 (SD 10), preop: 52 (SD 19)

VAS score: at 12 months 0, preop: 5

SF-36: Physical function, physical limitation, bodily pain, and social function improved significantly after surgery, physical component score also improved significantly at 12 months

No re-ruptures. Stitch abscess (1). Wound dehiscence (1)

Massoud 2017 [44]

G-flap

15

25 years

5 years (3–8)

Calf circumference, Range of motion

Calf circumference was equal to the uninjured side in 12 patients. Three patients had calf muscle hypotrophy, which averaged 1.3 cm in difference to the healthy side (range 1–2)

Active ankle motion range was equal to the contralateral in 14 patients

No re-ruptures. Superficial wound infection (3). Deep infection (1)

Kaul et al. 2020 [23]

G-flap

16

Not reported

At least 12 months

LEPPILAHTI

Leppilahti score: 12 months postop: 75% (12) had excellent result, 19% (3) had good result, and 6% (1) had fair result

No re-ruptures. Superficial surgical site infections (2). Delayed wound healing (1)

Guclu et al. 2016 [18]

G-flap

17

33 years

16 years (13–18)

AOFAS

AOFAS score: 95 (SD 3), preop: 64 (SD 4). Mean calf circumference difference: 3.4 cm (1–6). Mean 30 degrees plantar flexion and 120 degrees plantar flexion peak torques: 89 and 45 Nm. Mean deficiency in 30 degrees and 120 degrees: 16% and 17%

No re-ruptures. Superficial wound infection (2)

Sadek et al. 2015 [59]

G-flap

18

40.7 years

21.8 mosnths

AOFAS, calf circumference, Range of motion

AOFAS score: at 3 months 86.8 (82–99), at 6 months 94.6 (89–100), at 12 months 94.9 (89–100). Preop: 62.2 (40–85). ROM (plantar flexion): mean 43 degrees, healthy side was 45.8. Preop: 25.2

ROM (dorsiflexion): 19.4. Preop 21.2, healthy side 22.3

Calf hypotrophy: 3.3 (1–6) cm

No re-ruptures. Delayed wound-healing (2). Superficial wound infection (1)

Seker et al. 2016 [61]

G-flap

21

32.1 years

145.3 months

AOFAS, Range of motion, calf circumference, heel-raise, VAS, FADI. Peak torque

AOFAS score: 98.5 (90–100). FADI score: 98.9 (96.2–100). VAS score: 0. Calf circumference: 36.2 (30–40) compared with 37.2 (32–41) in healthy side. Ankle dorsiflexion: 18 (10–20) degrees compared with healthy side 19 (15–20) degrees. Plantar flexion: 30 (20–40) for both sides. Mean time for return to daily activities: 11.1 (8–16) weeks. Single heel rise was attainable after a mean of 14.1 (9–20) months after surgery. The mean plantar flexion peak torque for 30 and 120 degrees were 82 (70–142) and 42 (39–69) compared with the healthy side of 96 (70–145) and 43 (40–75). Median peak force deficiency was 6 (0–21) % at 30 degrees and 4.8 (0–12.5) % at 120 degrees. Mean dorsiflexion peak torque for 30 degrees: 51 (45–60) Nm compared with 55 (44–67) Nm on the healthy side. And the same bilaterally for 120 degrees with 39 (35–54) on the operative side and (31–55) on the healthy side

No re-ruptures. Superficial soft tissue infection (1)

Khiami et al. 2013 [25]

G-flap

23

52.1 years

24.5 months (12–43)

AOFAS

AOFAS score: 96.1 SD 6.8 (range, 79–100). Preop: 63.6 SD 11.5. The group without abnormal MRI signal had a mean AOFAS score of 98.3 SD 3.9, and those with abnormality 92.5 SD 10.5. Twelve patients resumed leisure sports at their previous level by a mean ± SD (range) 9.4 SD 2 months (7–12); three competitive sportsmen resumed sport at their previous level by a mean 7.6 months. MRI performed at 1 year showed increased tendon volume without abnormality in 57% (8/14) of cases; 43% (6/14) showed abnormal images

No re-ruptures. Partially regressive sural nerve hypoesthesia (1). Aseptic superficial skin necrosis (1). Septic partial tendon necrosis (1)

Pavan Kumar et al. 2013 [55]

G-flap

78

No mean, between 38–66 years

12 months

LEPPILAHTI, ultrasonography

LEPPILAHTI: 62 patients had excellent results (90-100p), 8 had good results (75-89p), 4 had fair results (60-74p), 2 had poor results (< 60p) and 2 were lost to follow up after 1 year. Nearly all patients resumed work at 6 months post-op and had normal walking, and stair climbing as well as normal dorsiflexion

No re-ruptures. Scar hypertrophy (2). Deep infection (1), superficial infection (2). Delayed wound healing (3)

Ozan et al. 2017 [52]

G-flap

15

35.2 years

19.6 months

Range of motion, Hooker, Heel-rise

Mean calf hypotrophy was 1.2 cm (0–2.5). No patient had any limitations to daily living and the active and passive ankle ROM was "good". Mean time to work was 38 months. The mean time for patients to return to daily activity was 3.2 months (range, 2—5 months). All patients were able to perform singe-leg heel rises. Hooker scores were excellent for 11 patients and satisfactory for 4 patients

No re-ruptures. No infection, no complications reported

Lins et al. 2013 [33]

ST-graft

13

42.2 years

12 months

AOFAS, Gait-pattern, Range of motion, Calf circumference

AOFAS score: at 6 months postop: 68.5 (SD 18.7), at 12 months postop: 85.2 (SD 18.7). The control group walked faster. Their stance phase was also shorter than patients affected by rupture. The calf circumference at 6 months was 257 compared with 24.5 at 12 months. The ROM-values were lower for the injured ankle at both 6 and 12 months

No re-ruptures. No infections. Weakness at the donor site (1)

El Shazly et al. 2014 [11]

ST-graft

15

37.7 years

24 months

AOFAS, Isokinetic testing

AOFAS score: at 24 months postop: 90.8. Preop: 32.6. Isokinetic testing showed a non-significant deficit (< 10%) of the plantar flexors on the injured side

No infections. Temporary sural nerve injury (1)

Bąkowski et al. 2020 [5]

ST-graft

18

53 years

15.3 months (12–24)

ATRS, VAS, QOL questions, calf circumference

ATRS improved significantly (no data). Lower calf circumference (no data). VAS pain 1.0. VAS satisfaction 9.0. Median EQ-5D 80.0. Heel-rise endurance 10.5 vs 7.0. Isokinetic flexor peak torque better on non-injured side, 91.3 vs 111. Single hop showed no statistical difference between injured and uninjured side

No re-ruptures. Moderate donor site pain and weakness (1)

Maffulli et al. 2014 [36]

ST-graft

26

46 years

31.4 months

ATRS, calf circumference, isometric strength, heel-rises

ATRS score: Postop latest follow-up: 86 (78–95). Preop: 42 (29–55). Calf circumference: 37.9 cm on the injured side vs 42.8 on the healthy side. Isometric 357 J on injured side vs 408 on healthy side. All patients could perform 10 heel-rises

No re-ruptures. No infections nor nerve injuries. Persistent pain over the distal operating wound (1)

Song et al. 2018 [63]

ST-graft

36

36 years

53 months

AOFAS, ATRS, VISA-A, Tegner

AOFAS score: Postop at latest follow-up 100 (86–100). Preop: 50 (5–75). VISA-A: Postop at latest follow-up: 94 (52–100). Preop: 23 (5–59). ATRS score: Postop at latest follow-up: 99 (84–100). Preop: 22.5 (6–67). Tegner score: Postop at latest follow-up: 4 (3–9). Preop: 1 (0–3)

No re-ruptures. No infections or nerve injuries. Pain related to the operation wound (4)

Dumbre et al. 2014 [10]

ST-graft

35

47 years

30.7 months (20–42)

Weight bearing MMT

Weight-bearing MMT postop at latest follow-up: 4/5. Preop: 2/5. Non-weight-bearing MMT postop at latest follow-up: 5/5

No re-ruptures. No complications reported

Maffulli et al. 2018 [38]

ST-graft

21

44.8 years

35.4 months

ATRS, calf circumference, plantar flexion strength

ATRS score: Postop at latest follow-up: 89.4 SD 3.2. Preop: 50.4 SD 7.5. Calf circumference postop: 38.7 cm SD 3.6 cm on the injured side, compared with 39.3 cm SD 3.4 cm on the healthy side. Plantar flexion strength: 424.3 N SD 42.9 N on the injured side, compared with 488.0 N SD 44.8 N on the healthy side

No re-ruptures reported. No complications reported

Bansal et al. 2021 [6]

ST-graft

10

45.1 years

12 months

AOFAS

AOFAS score: Postop at latest follow-up: 80.4. Preop: 40.8. All except one patient were able to walk on tiptoes

No re-ruptures. Superficial wound infection (1)

Gedam et al. 2016 [15]

ST-graft + G-flap

14

45.6 years

30 months (12–78)

AOFAS, ATRS

AOFAS score: Postop at latest follow-up: 96.9 (90–100). Preop: 64.5 (35–79). ATRS score: Postop at latest follow-up: 91.4 (83–97). Preop: 49.4 (30–70)

No re-ruptures. No complications reported

Li et al. 2020 [31]

ST-graft

26

44.2 years

15 months (12–18)

AOFAS, Plantar flexion strength, VISA-A scale, VAS

AOFAS score: Postop at latest follow-up: 91.3 SD 6.5. Preop: 44.9 SD 2.1. VISA-A: Postop at latest follow-up: 84.1 SD 3.9. Preop: 49.1 SD 3.2. VAS: Postop at latest follow-up 1.08 SD 0.3. Preop: 5.97 SD 0.7. Plantar flexion strength: Postop at latest follow-up: 133.7 N SD 17.5 N in injured side, compared with 141.5N SD 11.8 N in healthy side. All 26 was able to perform single leg heel-rises

No re-ruptures. No complications reported

Bai et al. 2019 [4]

ST-graft + G-flap

Total: 26,

G-flaps: 11,

ST-grafts: 15

36.7 years

12 months

AOFAS, Leppilahti score

ST-grafts: AOFAS score: Postop at latest follow-up: 93.5 SD 2.5. No preop measurement. Leppilahti score: Postop at latest follow-up: 95.1 SD 3.1. No preop measurement

Gastrocnemius-flaps: AOFAS score: Postop at latest follow-up: 92.6 SD 3.0. No preop measurement. Leppilahti score: Postop at latest follow-up: 94.7 SD 3.1. No preop measurement

No re-ruptures. Nerve injury (1 in ST-graft group). Infection (2 in G-flap group), DVT (2 in the Gastrocnemius-flap group)

Maffulli et al. 2013 [37]

ST-graft

26

42 years

8.2 years (7–10)

ATRS, calf circumference, isometric strength

ATRS at latest follow-up was 88. Lower isometric strength in injured side vs healthy side. Calf circumference 39.7 (SD 7.1) cm on the injured side vs 41.5 (SD 6.6) cm on the healthy side

No re-ruptures. Superficial wound infection (2). Wound adhesion (1)

Nilsson Helander et al. 2008 [47]

G-flap

28

46 years

29 months (12–117)

ATRS, questionnaire for symptoms, physical activity, and satisfaction

ATRS score: Postop at latest follow-up: 83 (24–100). 16 patients were satisfied with the final outcome

No re-ruptures. Deep infection (1), wound closure complication (2), DVT (2)

El Shewy et al. 2009 [12]

G-flap

11

34.3 years

7.45 years (6–9)

AOFAS, Holz scale, Range of motion, calf circumference

Holz scale: preop 10 poor, 1 fair. Postop 11 good. AOFAS: Preop 42.27 (39–46). Postop 98.9 (88–100). Ankle ROM (mean + SD): plantar flexion preop 20.5 SD 2.70. Postop 49.6 SD 1.5. Dorsiflexion preop 11.4 SD 3.23. Postop 17.7 SD 2.6. Calf (cm): Circumference (mean + SD)) Preop 31.6 SD 0.9. Postop 34.4 SD 0.89. Wasting (mean + SD) Preop 1.6 SD 0.4. Postop 0.7 SD 0.2

No re-ruptures. Small wound gaping (3), superficial wound infection (2)

Sarzaeem et al. 2012 [60]

ST-graft

11

30 years

25 Months

AOFAS, ATRS, Range of motion, Calf circumference

ATRS: Preop: 32 SD 6 (24–39). Postop: 89 SD 4 (82–95)

AOFAS: Preop: 70 SD 5 (61–78). Postop: 92 SD 5 (83–97)

Circumference: Injured side: 36 SD 3 (30–42) cm. Healthy side: 38 SD 4 (33–45) cm

ROM: Plantar flexion: Injured side: 36 SD 8 (22–50) degrees. Healthy side: 39 SD 6 (30–50) degrees. Dorsiflexion: Injured side: 13 SD 4 (5–20) degrees. Healthy side: 17 SD 4 (10–25) degrees

No re-ruptures. Superficial infection (2), DVT (1)

Takao et al. 2003 [65]

G-flap

10

51 years

75.1 months (26–192)

Calf circumference, Range of motion

AOFAS—Preop: 72.6 SD 5.3 (68–82). Postop: 98.1 SD 2.5 (94–100)

Cybex—30 degrees, preop: Torque effect ranged from 8 to 68% at the low setting and from 19 to 33% at the high setting. Postop, the torque ranged from –9% to 17% at the low setting and from –13% to 23% at high setting

Not reported

Mulier et al. 2003 [45]

G-flap with and without FHL

19

37 years

18 months

Leppilahti score, stiffness, muscle weakness, Range of motion, isokinetic calf muscle strength, CYBEX

Leppilahti: Postop Gastrocnemius -flap: Fair, 62 (48–78). Postop Gastrocnemius-flap + FHL: Good, 77 (67–89)

Cybex: G-flap: 23% (5–45) decrease in power and strength. Gastrocnemius -flap + FHL: 14% (5–35) decrease in power and strength

ROM: Gastrocnemius -flap: dorsiflexion 9 degrees (-5–20), plantar flexion 33 degrees (20–45). Gastrocnemius -flap + FLL: dorsiflexion 13 degrees (-5–25), plantar flexion 36 (20–45)

Re-rupture (1). Deep infection (1 in g-flap only), DVT (1 in each group, 2 total), delayed wound healing (3 in g-flap, 4 in Gastrocnemius-flap + FHL)

Lin et al. 2019 [32]

G-flap

20

38.5 years

32.8 months (12–68)

AOFAS, ATRS

ATRS: Preop: 39.6 SD 14.2 (20–72). Postop: 94.1 SD 4.9 (86–100)

AOFAS: Preop: 59.3 SD 12.3 (40–75). Postop: 96.6 SD 3.8 (90–100)

No re-ruptures. Superficial infection (1)

Werken et al. 1983 [67]

G-flap

10

51 years

At least 2 years

Calf circumference

Calf Circumference difference between the healthy and injured sided was 1–3.5 cm

No re-ruptures. Wound infection (2)

Gunaratne et al. 2021 [19]

G-flap

13

56 years

12 months

ATRS

Mean ATRS postop 72

Not reported

Nilsson et al. 2022 [46]

ST-graft

22

60 years

12 months

ATRS. ATRA. Heel-rise height. Heel-rise reps. Calf circumference. Ultrasonography. Concentric power. Heel-rise work

ATRS 76 (45–99). 89% were able to perform a single-leg heel-rise on the injured side. Tendon length 2.8 cm longer on the injured side compared with the non-injured and calf circumference 1.5 cm lower. ATRA was 60 (15) vs 49.5 (6) on the non-injured side. The same numbers for heel-rise height were 5.5 (5.75) vs 9.0 (2.75) and for heel-rise reps 11 (18) vs 26 (14)

No re-ruptures. 2 superficial wound infections and 1 sural nerve injury

Nordenholm, Nilsson et al. 2022 [49]

G-flap

22

61 years

12 months

ATRS. PAS. FAOS. Heel-rise height. Heel-rise reps. Calf circumference. Ultrasonography. CMJ. Heel-rise work. Hopping ratio. ATRA. Dorsiflexion range

Mean (SD) ATRS 62 (26) and mean (SD) PAS 3.5 (1.1). The patients performed less well in the heel-rise test on the injured side compared with the healthy side with a median (IQR) of 20 (10) vs 24 (12) in heel-rise repetitions (p = 0.004), 8 (7) vs 10 (8) cm in heel-rise height (p < 0.001), 872 (1740) vs 1590 (2145) joule in total heel-rise work (p = 0.001) and 0.37 vs 0.48 in hopping ratio (p = 0.005). Patients with chronic Achilles tendon rupture exhibited an elongation of the injured Achilles tendon with median (IQR) ATRA of 55° (3) compared with 50° (9) (p < 0.001) and a median of 22.4 (2.9) cm compared with 20.5 (2.0) cm measured by ultrasound (p = 0.06). Calf circumference was smaller on the injured side with a median (IQR) of 37 (4) compared with 38 (4) cm (p = 001)

No re-ruptures. 1 superficial wound infection

Nordenholm, Senorski et al. 2022 [50]

G-flap

23

61 years

12 months

Gait-analysis

Significantly reduced step width (0.01 m (p = 0.014)), increased speed (− 0.12 m/s (p = 0.013)), stride length (− 0.12 m (p = 0.002)), ankle moment (− 0.64 Nm/kg (p < 0.001)) ankle power (− 1.38 W/kg (p < 0.001)) and knee power (− 0.36 W/kg (p = 0.003)) compared with the preoperative status

Not reported

Raju et al. 2022 [57]

G-flap

12

47 years

34 months

Calf diameter. Dorsiflexion. Heel-rises. VAS. Rupp-score

Calf-diameter increased 2.2 cm. Dorsiflexion increased 10 degrees. Rupp-score with 5 excellent and 7 good

No re-ruptures or complications

Tsukada et al. 2022 [69]

ST-graft

10

52 years

35 months

AOFAS. ATRS. VAS. Months until the patient could perform 20 single-leg heel-rises

AOFAS increased significantly from 64.2 SD 5.6 (range 58–72) points preoperatively to 95.0 SD 5.3 (range 90–100) points at the final follow-up (P < 0.001), as did mean ATRS, from 29.8 SD 4.4 (range 22–35) points to 86.2 SD 7.7 (range 70–94), respectively (P < 0.001). Mean time between surgery and ability to perform 20 continuous double-leg heel rises of the operated foot was 13.5 SD 3.4 (range 10–18) weeks

Re-ruptures not reported. 1 sural nerve injury