Table 1.

Details of the included studies; NS = non-specified; RMQ = Roland Morriss Questionnaire; DRI = Disability Rating Index; VAS = visual analogue scale.

Authors (Year)	Study Design (Level of Evidence)	Number of Patients (M:F)	Mean Age (±or Range or SD) (Years)	Surgery	Timing of PT	Intervention	Control	Outcomes	Complications
Kjellby-Wendt et al. (1998) [14]	Randomized controlled trial (I)	- Early active training program (EAT): 26 (18:8) - Control group: 26 (20:6)	- EAT group: 41 years (range, 24–68 years) - Control group: 39 years (range, 21–66 years)	Lumbar microdiscectomy	Postoperative day 1 in both groups, but control group had a less active program	Education, lumbar braces, stretching, muscular strengthening exercises	Patients in the control group were treated with a less active training program after lumbar discectomy (17 min shorter the first 6 weeks and 21 min shorter the last 6 weeks)	Patients rehabilitated according to the EAT program had significantly less intense pain and more range of motion in the lumbar spine at 12 weeks after surgery. One year after surgery, there was no significant difference between groups in duration of sick leave and treatment satisfaction, even though the patients in the early therapy group were more satisfied compared to the controls (88% vs. 67%)	- ETA: 1 reoperation, 1 spondylolisthesis - Control: 1 reoperation, 1 reoperation at the same level of the lumbar spine
Kjellby-Wendt et al. (2001) [15]	Prospective randomized study (II)	- Early treatment group (EAT): 26 (18:8) - Control: 24 (18:6)	- Treatment: 41 (24–68) - Control: 37 (26–66)	Lumbar microdiscectomy	Postoperative day 1 in both groups, but control group had a less active program	Exercises to restore mobility of the trunk, reduce local edema, and stretch legs. Patients were encouraged to swim or jog	Traditional, less active training program	Both groups improved pain severity and state of anxiety. The multidimensional pain inventory improved more in the EAT group	NS
Erdogmus et al. (2007) [16]	Randomized control trial (I)	- No therapy: 40 (25:15) - Sham therapy: 40 (21:19) - Physical therapy: 40 (21:19)	- No therapy: 41.8 ± 10.4 - Sham therapy: 42.3 ± 9.8 - Physical therapy: 39.8 ± 10.5	Standard laminectomy and either discectomy or microdiscectomy procedure	Within the first postoperative week in both groups, but control group had sham therapy or no therapy at all until after the first 3 months	Education, stretching, endurance exercises	- No therapies for the first 3 postoperative months. - Sham therapy: only massages for 30 min	After 12 weeks, low back pain was significantly less in physical therapy group than in untreated group. After 1.5 years, there were no significant outcome differences, including secondary outcomes (return to work, patient satisfaction, and activity of daily living)	- No therapy: 2 re-herniations - Sham therapy: 2 re-herniations - Physical therapy: 1 re-herniation
Millisdotter et al. (2007) [8]	Prospective controlled trial, not randomized—Level II	- Total: 56 (36:20) - Early Training (ET): 25 (19:6) - Control: 31 (17:14)	- Total: 38 - ETG: 37 - CG: 31	Open microscopic lumbar disc discectomy	- Early training group (ETG): 2 weeks after surgery - Control group (CG—traditional training): after 6 weeks	Education, neuromuscular closed-chain exercises	Control group (CG—traditional training): stabilization exercises mainly using different types of stationary gym equipment and focused on coordination and mobility	Early neuromuscular customized training had a superior effect on disability (RMQ and DRI), with a significant difference compared to traditional training at follow-up 12 months after surgery. No differences in terms of pain (VAS) between groups	- Early training: 2 revision surgeries - Control: 1 revision surgery
Newsome et al. (2009) [17]	Prospective randomized control trial (I)	- Intervention group: 15 (7:8) - Control: 15 (11:4)	- Intervention group: 38 (27–43.3) - Control: 37 (30.5–45)	Lumbar microdiscectomy	- Intervention group: postoperative hour 2 - Control: postoperative day 1	Passive hip and knee flexion toward the chest. Mobilization out of bed and education	Started on postoperative day 1, similar care but no knee and hip flexion	Significantly reduced time to independent mobility and return to work (median 6 vs. 8 weeks in the intervention group compared with the control group). At 15 h after surgery, independent mobility was attained in 80 and 40% of the intervention and control groups, respectively. There were no significant differences in disability and pain scores at 4 weeks and 3 months	- Intervention: 1 recurrence of symptoms - Control: 1 recurrence of symptoms
Abbott et al. (2010) [18]	Randomized control trial (I)	- Total: 107 (41:66) - Control: 54 (23:31) - Physical therapy: 53 (18:35)	- Control: 50.3 ± 10 - Physical therapy: 51.0 ± 10.9	Lumbar fusion surgery	Starting from postop week 3 in both groups, but controls had a less active program	Education, motor relearning exercises, cognitive behavioral relearning exercises	Patients in the control group received education on walking, daily living exercises, and activity restrictions	Physical therapy improved functional disability, self-efficacy, outcome expectancy, and fear of movement/(re)injury significantly more than control group at the respective follow-up occasions. Similar results occurred for pain coping, but group differences were non-significant at 2 to 3 years of follow-up	- Control: 2 removals of instrumentation, 1 adjacent-level degeneration, 2 pseudoarthroses - Physical therapy: 5 removals of instrumentation, 2 adjacent-level degenerations, 5 pseudoarthroses
Oestergaard et al. (2012) [9]	Randomized control trial (II)	- Total: 82 (38:44) - Intervention: 41 (21:20) - Control: 41 (17:24)	- 6 weeks: 52 ± 8.5 - 12 weeks: 51.3 ± 9.9	Lumbar spine fusion for degenerative disc disease	- Intervention: starting at postop week 6 - Control: postop week 12	Education, muscle strengthening, exercises focusing on trunk and large muscle groups	The same physical therapy protocol, but started at 12 weeks	According to the Oswestry Disability Index, at 1-year follow-up, the 6-week group had significantly lower median reduction compared to the 12-week group. The Dallas Pain Questionnaire showed the same tendency overall, and daily activities were significantly reduced in favor of the 12-week group. For back pain, the 6-week group had a median reduction similar to the 12-week group. The results at 6 months of follow-up were similar. No difference was found in return to work 1 year post-surgery	- 6 weeks: 3 revision surgeries, 2 removals of instrumentation - 12 weeks: 5 revision surgeries, 2 removals of instrumentation
Ju et al. (2012) [19]	Randomized control trial (II)	- Exercise therapy group (ETG): 7 - Control: 7	- ETG: 45.2 ± 3.96 - CONG: 46.2 ± 5.3	Lumbar disc discectomy	- Exercise Therapy Group: postoperative week 2 - Control: no physical therapy	Lumbar extension program, resistance exercises	The control group did not participate in any exercise rehabilitation programs	ETG showed significant improvements in all items that measured lumbar extensor muscle strength and pain after the intervention, but the control group did not exhibit any significant improvements	NS
Oestergaard et al. (2013) [20]	Randomized control trial (I)	- Total: 82 (38:44) - 6 weeks: 41 (21:20) - 12 weeks: 41 (17:24)	- 6 weeks: 52 ± 8.5 - 12 weeks: 51.3 ± 9.9	Lumbar spine fusion for degenerative disc disease	- Intervention: starting at postop week 6 - Control: postop week 12	Education, muscle strengthening, exercises focusing on trunk and large muscle groups	The same physical therapy protocol, but started at 12 weeks	No statistically significant difference was found in walking distance or fitness over time. In both groups, the patients achieved an overall increase in walking distance but no improvement in fitness	- 6 weeks: 3 revision surgeries, 2 removals of instrumentation - 12 weeks: 5 revision surgeries, 2 removals of instrumentation
Oestergaard et al. (2013) [21]	Randomized control trial (I)	- Total: 82 (38:44) - 6 weeks: 41 (21:20) - 12 weeks: 41 (17:24)	- 6 weeks: 52 ± 8.5 - 12 weeks: 51.3 ± 9.9	Lumbar spine fusion for degenerative disc disease	- Intervention: starting at postop week 6 - Control: postop week 12	Education, muscle strengthening, exercises focusing on trunk and large muscle groups	The same physical therapy protocol, but started at 12 weeks	The 6w group had significantly poorer outcome in relation to functional disability than the 12w group. The same tendency was found for QALY, although this difference was not statistically significant	- 6 weeks: 2 readmissions before rehabilitation - 12 weeks: 1 readmission before rehabilitation
Ozkara et al. (2015) [22]	Prospective randomized control study (II)	- Treatment group: 15 (6:9) - Control: 15 (7:8)	- Treatment group: 48.5 ± 11.9 - Control: 44.1 ± 8.8	Lumbar disc discectomy	Postoperative day 1 in both groups, but control group did not perform any exercises but only education	Education, exercises for pelvic tilt, abdominal and isometric quadriceps strengthening. Back exercises, leg raises, and hip flexions were added after the sixth week	Only instructions regarding lying, standing, sitting, and walking	When the groups were compared at week 12, a statistically significant difference was found in the VAS, Oswestry Low Back Pain Disability Questionnaire, and physical functioning of the SF-36, including body pain and social functioning subparameters. There was no significant difference in terms of return to work and patient satisfaction	NS
Oosterhuis et al. (2017) [23]	Multicenter, randomized, controlled trial (I)	- Experimental group: 92 (38:54) - Control: 77 (20:57)	- Exp: 47 (12) - Con: 47 (12)	Lumbar disc discectomy	- Experimental group: starting the first week after discharge - Control: only education after discharge	Education, daily activity training, gradually increasing intensity of exercises	Participants assigned to the control group were not referred for rehabilitation after discharge from the hospital	No clinically relevant or statistically significant overall mean differences between rehabilitation and control for any outcome adjusted for baseline characteristics (global perceived recovery, functional status, leg pain, back pain, physical health, and mental health)	- Exp: 1 nerve root injury, 2 dural tears - Control: 1 nerve root injury, 2 dural tears, 1 increase in sensimotor deficit
Kernc et al. (2018) [24]	Randomized controlled trial (I)	- Control group: 14 (5:9) - Training group: 13 (9:4)	- Control group: 60.3 ± 8.1 - Training group: 61.1 ± 8	One-level instrumented trans-foraminal interbody fusion	- Training group: starting 3 weeks after the surgery - Control group: started 3 months postoperatively	Isometric exercises focused on trunk extension, flexion, and lateral flexion muscles. Leg adduction and hip extension	- Control group: no exercises or physical therapy prior to 3 months postoperatively	Both groups improved their walking speed after 3 months, although improvement in the training group was significantly greater than that in the control group. The training group significantly improved in all isometric trunk muscle measurements	- Training group: 0 - Control group: 2 hardware loosenings
Zhang et al. (2021) [25]	Randomized controlled trial (I)	- Total: 92 (48:44) - Intervention group: 46 - Control group: 46	57.4 ± 6.1 (20–68)	Percutaneous trans-foraminal endoscopic discectomy	- Intervention group: started at postoperative day 1 - Control group: no exercises were performed	Education, daily activity training, extension and flexion exercises of lower limbs, back muscle exercises	Control group performed routine functional exercises after their operations (not mentioned when)	Scores for residual lumbocrural pain, straight leg raising, muscle strength, sensory (skin), nerve reflex, and lumbar function of patients in the intervention group were significantly better than those of the control group	NS