Percutaneous Transforaminal Endoscopic Discectomy Learning Curve: A CuSum Analysis

Thursday, June 1, 2023

8:30 AM – 6:15 PM

Location: Salons 7-8

Co-Author(s)

OM

Omri Maayan, BS

Hospital for Special Surgery, United States

View E-Poster

Presenting Author (Person doing the Podium Present(s)

AP

Anthony Pajak, BS

Hospital for Special Surgery, United States

Co-Author(s)

PS

Pratyush Shahi, MBBS

Hospital for Special Surgery
New York, New York, United States
TS

Tejas Subramanian, BS

Hospital for Special Surgery, United States
KA

Kasra Araghi, BS

Research Fellow
Hospital for Special Surgery
Scottsdale, Arizona, United States
MK

Maximillian Korsun, BS

Hospital for Special Surgery, United States
NS

Nishtha Singh, MBBS

hospital for special surgery, United States
EZ

Eric Zhao, BS

Hospital for Special Surgery, United States
OT

Olivia Tuma, BS

Hospital for Special Surgery
New York, New York, United States
TA

Tomoyuki Asada, MD

Hospital for Special Surgery, United States
SS

Sumedha Singh, MD, MBBS

Hospital for Special Surgery, United States
SQ

Sheeraz A. Qureshi, MD, MBA

Attending Surgeon
Hospital for Special Surgery
York, New York, United States
SI

Sravisht Iyer, MD

Assistant Attending, Spine Surgery
Hospital for Special Surgery
New York, New York, United States

Submitter(s)

HS

HSS SpineTeam

New York, New York, United States

Disclosure(s):

Tejas Subramanian, BS: No financial relationships to disclose

Nishtha Singh, MBBS: No financial relationships to disclose

Tomoyuki Asada, MD: No financial relationships to disclose

Sravisht Iyer, MD: No financial relationships to disclose

Introduction:
Percutaneous transforaminal endoscopic discectomy (PTED) is a less invasive alternative to tubular microdiscectomy for lumbar disc herniations. Although the learning curve for PTED is purported to be steep, it has not yet been standardized in the literature.
Aims/

Objectives:
The purpose of this study is to describe the learning curve for PTED and the cutoff point required to achieve technical proficiency.

Methods:
This retrospective cohort study included consecutive patients who underwent lumbar PTED by a single surgeon between December 2020-2022. Cumulative Sum (CuSum) analysis was applied to operative and fluoroscopy time to assess the learning curve. Observed inflection points were used to divide cases into early and late phases. The two phases were analyzed for differences in operative and fluoroscopy time, length of stay (LOS), operative complications, and patient-reported outcome measures (PROMs). Baseline parameters including patient demographics, body mass index (BMI), Charlson Comorbidity Index (CCI), comorbidities (smoking, hypertension, stroke, lung disease, osteoporosis, anxiety, depression), and operated levels were also compared. PROMs entailed the Oswestry Disability Index (ODI), Patient-Reported Outcomes Measurement Information System (PROMIS), Visual Analog Scale (VAS) Back/Leg, and 12-Item Short Form Survey Physical and Mental Component Scores (SF-12 PCS and MCS) at preoperative, early postoperative ( < 6 months), and late postoperative (> 6 months) timepoints. Early and late phase cases were subsequently divided in half (Early Phase: Group A and B; Late Phase: Group C and D) to allow for intra-group comparisons. Alpha was set at 0.05.

Results:
55 patients were included. The most common operated level was L4-5 (45%). CuSum analysis indicated that both operative and fluoroscopy time diminished rapidly after case 31, indicating a learning curve of 31 cases for PTED (Early Phase n=31; Late Phase n=24). The late-phase cases exhibited significantly lower operative times (85.7 vs 62.2 minutes, p=0.001) and fluoroscopy times (131.0 vs 97.2 seconds, p=0.001) compared to the early-phase cases. Despite the learning curve, both early- and late-phase cases showed significant improvement in all PROMs at the early and late timepoints with no significant differences in the magnitude of improvement between the two phases. In addition, there were no significant differences in baseline demographics, BMI, CCI, comorbidities, operated levels, LOS, or complications between (Early vs Late) or within (Group A vs B; Group C vs D) phases.

Conclusions:
The learning curve for PTED was found to be approximately 31 cases. Importantly, this learning curve did not seem to impact PROMs or complication rates. The information herein presented may prove beneficial as more spine surgeons incorporate PTED into their armamentariums.