To unlock this feature and to subscribe to our weekly evidence emails, please create a FREE orthoEvidence account.


Already Have an Account?

Visit our Evidence-Based Covid-19 Website and Stay Up to Date with the latest Research.
Ace Report Cover

Autologous bone cage in PLIF offers similar 2-year results to PEEK cage

Cite This
+ Favorites
Cite This
+ Favorites

Autologous bone cage in PLIF offers similar 2-year results to PEEK cage

Vol: 6| Issue: 3| Number:13| ISSN#: 2564-2537
Study Type:Therapy
OE Level Evidence:2
Journal Level of Evidence:N/A

Comparison of the PEEK cage and an autologous cage made from the lumbar spinous process and laminae in posterior lumbar interbody fusion

BMC Musculoskelet Disord. 2016 Aug 30;17(1):374

Did you know you're eligible to earn 0.5 CME credits for reading this report? Click Here


69 patients scheduled for single-level posterior lumbar interbody fusion were randomized to one of two different implant groups: one group received an autologous cage consisting of the resected spinous process and lamina (ACSP) from earlier in the procedure, and one group received a polyetheretherketone (PEEK) cage. The purpose of this study was to determine and compare clinical and radiographical results of the ACSP group in comparison to the PEEK cage group over 24-month follow-up. Results demonstrated no significant differences between groups in either visual analog pain scores, functional status, fusion success, restoration of disc height, or regional lordosis of the operative level.

Publication Funding Details +
None disclosed

Risk of Bias


Reporting Criteria


Fragility Index


Was the allocation sequence adequately generated?

Was allocation adequately concealed?

Blinding Treatment Providers: Was knowledge of the allocated interventions adequately prevented?

Blinding Outcome Assessors: Was knowledge of the allocated interventions adequately prevented?

Blinding Patients: Was knowledge of the allocated interventions adequately prevented?

Was loss to follow-up (missing outcome data) infrequent?

Are reports of the study free of suggestion of selective outcome reporting?

Were outcomes objective, patient-important and assessed in a manner to limit bias (ie. duplicate assessors, Independent assessors)?

Was the sample size sufficiently large to assure a balance of prognosis and sufficiently large number of outcome events?

Was investigator expertise/experience with both treatment and control techniques likely the same (ie.were criteria for surgeon participation/expertise provided)?

Yes = 1

Uncertain = 0.5

Not Relevant = 0

No = 0

The Reporting Criteria Assessment evaluates the transparency with which authors report the methodological and trial characteristics of the trial within the publication. The assessment is divided into five categories which are presented below.




Outcome Measurements


Inclusion / Exclusion


Therapy Description



Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65

The Fragility Index is a tool that aids in the interpretation of significant findings, providing a measure of strength for a result. The Fragility Index represents the number of consecutive events that need to be added to a dichotomous outcome to make the finding no longer significant. A small number represents a weaker finding and a large number represents a stronger finding.

Why was this study needed now?

Posterior lumbar interbody fusion is a standard procedure performed in the treatment of patients with degenerative lumbar disc disease. Synthetic fusion cages made of polyetheretherketone (PEEK) are often used to complete these procedures. While generally accepted as providing patients with excellent outcomes, PEEK cages, as a result of their synthetic nature, can result in long-term complications and need for removal. An autologous graft composed from en bloc resection of the spinous process and laminae during surgery has been suggested as a possible alternative, although data on the efficacy of this graft material is limited.

What was the principal research question?

In posterior lumbar interbody fusion, is there any significant difference between an autologous cage made from the lumbar spinal process and lamina and a standard, synthetic polyetheretherketone (PEEK) cage in clinical and radiological results over 24-month follow-up?

Study Characteristics -
69 patients, between 30 and 70 years of age, scheduled for posterior lumbar interbody fusion due to symptomatic single-level degenerative lumbar disease for at least 6 months. All cases were performed under general anesthesia, with procedures standardized except for the randomized implant material. Following exposure of the spinous process and lamina, en bloc resection was performed. Decompression and discectomy were then performed, followed by measurement for implant sizing.
ACSP group: The implant was made up from the resected spinous process and lamina harvested previously during the procedure. The spinous process was trimmed appropriate to the size of implant needed (bone block), while the lamina was cut into small pieces to allow for impacting of the main bone block. Lastly, interpedicular screws were inserted and connected via rods. (n=34)
PEEK group: Following discectomy, a polyetheretherketone (PEEK) cage was inserted into the intervertebral space, with interpedicular screws and rods used as in the ACSP group. (n=35)
Clinical assessment was made through a visual analog scale (VAS) for pain, as well as the Kirkaldy-Willis criteria, which grades patients as either Excellent, Good, Fair, or Poor based on the ability to return to work and activities of daily living. Anteroposterior and lateral flexion-extension radiographs were used to assess fusion status. Computed tomography (CT) was used to assess disk height and regional lordosis (ie. angle of the upper and lower edges of the operated intervertebral disc).
RCT; Assessor-blind, Single-surgeon
Follow-up scheduled for 3, 6, 12, and 24 months after surgery.

What were the important findings?

  • VAS pain scores improved significantly from preoperative to postoperative within both the ACSP group (7.54+/-1.24 to 2.05+/-0.61) and the PEEK group (7.23+/-0.88 to 1.86+/-0.63); the difference between groups in postoperative VAS pain score was not statistically significant (p>0.05).
  • An "Excellent" or "Good" functional rating was given to thirty patients of each group; the remaining patients in each group were rated as "Fair". No patient of either group was rated as having a "Poor" functional outcome.
  • Successful fusion within 8-12 weeks of surgery was documented in >90% of patients in both groups, and 100% of patients by 24 months.
  • Disc height increased preoperatively to postoperatively in the ACSP group from 21.50+/-4.77mm to 43.29+/-3.62mm, and in the PEEK group from 21.91+/-3.75mm to 45.43+/-3.51mm; the difference between groups in postoperative disc height was not statistically significant.
  • No significant differences between groups were observed in regional lordosis of PLIFs at either L3/4, L4/5, or L5/S1 (all p>0.05).
  • One superficial wound infection occurred in the PEEK group. No cases of surgery-related neurological injury or hardware failure were documented in either group.

What should I remember most?

In instrumented single-level posterior lumbar interbody fusion, cases completed with an autologous cage using the resected spinal process and lamina during the procedure demonstrated similar clinical and radiological results to those completed with a polyetheretherketone (PEEK) cage.

How will this affect the care of my patients?

The results of this study suggest that an autologous cage using the resected spinal process and lamina in posterior lumbar interbody fusion may offer an effective alternative to standard PEEK cages in these procedures. While the body of evidence on the use of the autologous cage used in the current study is still limited, if consistent efficacy is demonstrated in subsequent studies, it could represent a more inexpensive alternative to synthetic PEEK cages.

CME Image

Did you know that you’re eligible to earn 0.5 CME credits for reading this report!


Join the Conversation

Please Login or Join to leave comments.

Learn about our AI Driven
High Impact Search Feature

High Impact Icon

Our AI driven High Impact metric calculates the impact an article will have by considering both the publishing journal and the content of the article itself. Built using the latest advances in natural language processing, OE High Impact predicts an article’s future number of citations better than impact factor alone.