Cage Migration of Lumbar Interbody Fusion Cage

  Just heard a buzz from a representative of German Spine company that titanium lumbar cage is revived in Europe instead of PEEK cage. That, titanium cage has less incidence of migration than PEEK cage.

Cage protruded posteriorly. L5-S1 PLIF Ti Cage + pedicle screw,

  Talking about pull out force of both materials , it is understandable from this paper: "The titanium cage pull out force was significantly (P=0.0002) higher compared to both radiolucent cage constructs."
 No wonder, the hearsay may be true of higher incidence of PEEK cage migration.
  Even you make a bigger footprint of PEEK cage, migration is still likely :"The larger footprint radiolucent cage did not increase stability as compared to the standard footprint."

PEEK stand-alone cage at L3-4 level; the cage migrated persistently inside the space  eroding the vertebrae and resulted in a big defect (red arrow). The 58 y/o male was disabled then cured by other method.

  Supplemental posterior instrumentation is not even a safeguard to prevent migration of PEEK cage.
  Fortunately, this case report used lateral access, and the cage migrated to lateral side, no sequel occurred. The authors are thinking about solution of putting a lateral plate with screws to prevent the cage slip away.

  Posterior migration may result in disaster, either titanium or PEEK are alike.

Implanting Fusion Cages in Pig's Vertebrae.

Meet Henry (if presumed male) or Mary, the lab guys did not know the sex, or they kept it as confidential to protect him/her.

Pig has 5 to 7 lumbar vertebrae.  Interestingly, implanting lumbar fusion cage (much smaller ones than in human lumbar interspace, the size is similar to cervical cage for human) is not as difficult as I once thought.  The approach is my preferred one: lateral access. Using this approach, there was not much bleeding, but the psoas muscle had to be transected in order to expose 3 to 4 levels of lumbar discs. The caudal disc (above sacrum) could not be accessed due to obstruction by the pelvis.  But in human, the last lumbar disc can be accessed laterally after mobilizing the great veins, plus other tricks.
  To my surprise, those pigs who had the psoas muscle transected did not have lumbar nerve injury occurred. Unlike human, the opposite is true. All those pigs survived well after cage implantation, without limp, life was as usual: eat, hanging around, and sleep, but no sex, all were castrated. But they seemed to have a short period time of melancholy, possibly due to surgical pain.
  Pig's lumbar disc heights are pretty narrow, may be less than 5 mm. Also the axial surface is more elongated, unlike the oval shape of human disc. The AP diameter may be only 1/2 of transverse diameter.

Axial view of pig's lumbar disc

Implanting the cage in is a difficult task, because of the narrow disc height. Wedge osteotomy has to be done in order to get the curet inside the disc space and clean out disc material. Complete discectomy is difficult not to mention decortication. It seems that only lateral 1/2 or 1/3 of discectomy can be done. Cage insertion is another challenge that you have to use force to punch the cage in. Metal cage is fine but PEEK cage has to be careful not to break it during hammering.

3 months follow-up X-ray. No idea if fused or not.

    Sacrificing the pig and take the lumbar column out is a new experience.  This only happens in autopsy which surgeons rarely do. Fortunately, it is not my routine work. The lab did not provide the necessary tools (chisel, osteotome), the column had to be transected using hand saw.

International Video Conference, Rome and Taipei, April 16, 2011

 April 16 afternoon from 2 to 7 pm (Taipei time; 9 am-2pm Rome time), we held a video conference between Rome and Taipei. The organizer was MOVINGTECH, Rome, Italy, which is an emerging spine product company in Europe. The CEO, Mr. Diego (Herr Diego Pizzicaroli) is an intelligent, humorous, ambitious, and honest gentleman, together with his diligent staffs (Mr. Giuseppe Tricarico, Ms.Daniela Pellegrino, and others; Mr. Mr. Sabatino Vittorio was not available due to tiredness, a regret)

Dr. Bambang (far left), Prof. Lu (middle), me (right), Mr. Jerry Lin (standing), and his secretary Cindy.

Scene of video conference. The assistants: a German interpreter (the lady in the middle), and two ladies from MediaPlus (left and right).

 The scientific video conference was successfully accomplished. The international participants were from Germany, Italy, Indonesia, Hong Kong, and Taiwan.  There were a total of 18 professionals; On European side (Rome, Italy), there were 15 famous German and Italian professors and spine surgeons joined the meeting (they were from various cities in Germany and Italy); on Asian side (Taipei, Taiwan), there were three speakers: Indonesian (Dr. Bambang Darwano), Hong Kong (Professor William Lu, of Hong Kong University), and me (BoneCare Orthopaedic Center).
 The main theme of the conference was to introduce and demonstrate new spine products to the audience: Vessel-X, Vessel-lock, and bioactive cement (Sr-HA) from Mr. Jerry Lin, Taiwan, and Latero of my own design for lumbar interbody fusion.
  The first speaker was Dr. Jaqeline Repman (Mr. Diego's spouse, a seasoned German orthopaedic surgeon), she lectured about her experience of using Vessel-X in treating osteoporotic vertebral fractures, the most feared cement leakage was contained by a perforated bag of Vessel-X; I was the second, introducing the concept of Latero, results of biomechanical test compared with SynFix (Synthes, Switzerland), and its clinical outcomes of Latero in various lumbar disorders requiring interbody fusion. Dr. Bambang talked about Vessel-lock in stabilizing and treating kyphosis due to multiple-level vertebral osteoporotic compression fracture with satisfying outcomes. Professor Lu introduced Strontium (Sr, an element near identical to calcium) based bioactive cement, his extensive lab (animal) studies was impressive; the shortcomings of bone cement (PMMA) may have a better alternative to alleviate.
 All agenda were right on time, just the same as in a formal international conference. The Q & A section was non-stop from the audience, and translated by a German lady from our side. The voices from both sides were clearly heard and answered liked that we all sat in the same room
 When we look at the incidence of several most commonly performed spine procedures, vertebroplasty (or kyphoplasty), and lumbar interbody fusion are the leading twos, due to global aging societies. Both procedures have many medical products from various companies to achieve the same goals of pain relief and to improve quality of life.  However, surgical complications are not uncommon and may result in devastating insult to the patients. To minimize complications and protect patients, the new, safe, and proved medical products are the utmost priority.
 This international video conference demonstrated new ways to treat osteoporotic compression fractures and various lumbar disorders requiring interbody fusion. We all wish more video conferences planned in the future to communicate and exchange ideas synchronously at different countries without the expense of flight and time. Lastly, I would like to thank Mr. Diego for his hard working, Dr. Bambang and Professor Lu for flying to Taipei to attend the conference.