Table 1

Summary of proximal juntional tether studies include in the present review.

Study	Study Design	Level of Evidence	Patients, n	Patient Population	Mean Age, y	Mean Follow-Up, mo	Tether	Clinical Outcome
Alluriu et al27	Retrospective cohort	III	83	ASD patients	64	20.3	Semitendinous allograft	PJK present in 33% (16/49) of patients in tether group and 32% (11/34) of patients in control group (P = 0.31); PJF occurred in 18% (6/34) in control group but did not occur in tether group (P = 0.01)
Buell et al28	Retrospective cohort	III	120	ASD patients with instrumentation at >6 motion segments without transitional rods or hooks at UIV; all had lower-thoracic UIV (T9-T11)	67	28	Mersilene polyethylene tape	Tethers significantly reduced PJK in ASD patients with lower-thoracic UIV (OR = 0.063, 95% CI = 0.016–0.247, P < 0.001); risk factors for PJK in patients with tether were greater postoperative lordosis of upper lumbar spine and greater UIV angle
Buell et al29	Retrospective cohort	III	184	ASD patients with instrumentation at >6 motion segments without transitional rods, hooks at UIV, or vertebral augmentation	66	20	Mersilene polyethylene tape	PJK rates: 45.3% (29/64) in no-tether group; 34.4% (22/64) in tether-only group; and 17.9% (10/56) in tether with crosslink group; PJK rate was lower for all tethered (26.7%) vs no-tether groups (P = 0.011)
Iyer et al30	Retrospective cohort	III	108	ASD patients with >5-level fusion to the pelvis	55	17.6	Mersilene polyethylene tape	Rates of PJK in tether group (27.3%) and no-tether group (28.6%) were similar (P = 0.827); tether was not protective against PJK
Line et al31	Prospective cohort	II	625	ASD patients with >5 levels fused posteriorly	58.6	31	Polyethylene tether assessed in the context of other PJK preventive approaches (cement, hook, and avoidance of overcorrection)	If no PJF prophylaxis used and sagittal plane overcorrected, PJF rate was 24.2%; if PJF prophylaxis used, PJF rate was significantly lower (10.6%, P < 0.05) and further reduced to 9.9% if also not overcorrected; PJF rate similar (P > 0.05) for cement (12.1%), hooks (7.0%), and tether (16.1%)
Pham et al32	Retrospective case series	IV	4	ASD patients with long-segment spinal fusion to the upper-thoracic spine	60	5.5	Semitendinous allograft	None of the 4 patients developed PJK at 5.5 mo follow-up; mean PJA increased by 3°
Rabinovich et al33	Retrospective cohort	III	184	ASD patients with >5 level fusions to the pelvis	67	45.4	Mersilene polyethylene tape	PJK rates: 60.7% (37/61) in no-tether group; 35.7% (15/42) in tether-only group; and 23.3% (10/43) in tether with crosslink group; rate of PJK in no-tether group was significantly higher than in tether group (60.7% vs 29.4%, P < 0.001); PJK rate was lower in tether with crosslink vs no-tether group (P = 0.016);
Rabinovich et al34	Retrospective case series	IV	71	ASD patients with long-segment spinal fusion	66	14	Polyethylene-terephthalate tape	PJK occurred in 15%; PJA increased by mean of 4°; rates of symptomatic PJK and revision for PJK were 8.8% and 2.9%, respectively
Rodnoi et al35	Retrospective cohort	III	43	ASD patients with fusion from throacolumbar junction (T9–L1) to the pelvis	69	24	Mersilene polyethylene tape	Rate of PJK was significantly higher in no-tether group (17/20; 85%) vs tether group (10/23; 43.5%; P = 0.01); rate of PJF was significantly lower in tether group (0/23, 0%) vs no-tether group (7/20, 35%; P = 0.003)
Rodriguez-Fontan et al36	Retrospective cohort	III	80	ASD patients with >3 levels fused posteriorly	62.3	24	Mersilene polyethylene tape	PJK rate at 2-y follow-up was 15% in tether group and 38% in no-tether group (OR = 0.28, P = 0.04); higher latent period to PJK for tether vs no-tether group (20 vs 7.5 mo, P = 0.018); tether reduced PJK risk after adjusting for confounders (age >55 y, 7–15 levels fused, thoracic UIV, BMI >27, osteoporosis)
Safaee et al37	Retrospective cohort	III	200	ASD patients undergoing instrumented fusion	64	Minimum 6	Soft sublaminar cable	Mean change in PJA was 6° in tether group vs 14° in no-tether group (P < 0.001); PJF rate in tether group was 4% (4/100) vs 18% (18/100) in no-tether group (P = 0.002)
Safaee et al38	Retrospective cohort	III	319	ASD patients undergoing instrumented fusion	65	Minimum 12	Soft sublaminar cable	Rate of reoperation for PJF significantly lower in tether group (8/242, 3.3%) vs no-tether group (12/77, 15.6%; P < 0.001); for patients with upper-throacic UIV, rate of PJF was 0% in tether group vs 6.7% in no-tether group (P = 0.014); for patients with lower-thoracic UIV, rate decreased from 21.3% to 5.3% (P = 0.001); on multivariate analysis, only use of tether and greater number of fused levels were associated with reductions in the rate of reoperation for PJF
Viswanathan et al39	Prospective cohort	II	40	ASD patients undergoing thoracic to ilium instrumentation	64	12 (median)	Braided sublaminar band	PJK developed in 3 of 40 (7.5%) patients; no instances of PJF; 3 procedure-related complications (2 CSF leaks and 1 transient neurological deficit)
Yagi et al40	Retrospective cohort	III	64	ASD patients undergoing instrumented fusion from lower throacic spine to sacrum	67	Minimum 24	Sublaminar polyethylene band	PJA was significantly greater in the no-tether group (17° vs 8°, P < 0.001); incidence of PJF was lower in the tether group (3% vs 25%, P = 0.03), with an OR of 0.1 (95% CI: 0.0–0.8, P = 0.03)
Zaghloul et al41	Retrospective case series	IV	23	ASD patients treated with long-segment posterior instrumented fusion	63	11.9	Mersilene polyethylene tape	None of the patients had developed PJK (0%) as of last follow-up

Abbreviations: ASD, adult spinal deformity; BMI, body mass index; CI, confidence interval; CSF, cerebrospinal fluid; OR, odds ratio; PJA, proximal junctional angle; PJF, proximal junctional failure; PJK, proximal junctional kyphosis; UIV, upper-most instrumented vertebra.