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.

Functional Analgesic Discography (FAD), what happened?

 Functional Analgesic Discography (FAD), a once promising successor of provocative discography (PD) in diagnosing discogenic low back pain. PD, the already bruised gold standard, has been beaten by Dr. Carragee to half dead and stays at the intensive care unit at this moment. For surgeons and radiologists alike, we almost lost a strong persuader to lure the patients into the operating or radiology rooms.

 FAD is a simpler test than PD that you inject anesthetic agent into the suspected disc, then ask the patients whether their chronic, daily agonizing low back pain has been decreased or gone. If so, lumbar interbody fusion surgery then may be indicated.
 Curiously, the FAD  clinical trial had been withdrawn prior to enrollment, dated Sept. 15, 2010.
 What happened?
 Here, if the news of withdrawn was true, I would like to do a mini-autopsy of this still-born yet important functional test, based on my personal experience of FAD in last 6 years:
 1. in relatively hydrated discs (young patients), the anesthetic agent may be contained inside the nucleus and cannot reach the annulus or bony endplates which have rich yet abnormal innervation (presumed to be the pain sources), hence no analgesic effect occurs;
 2. the amount of anesthetic agent injected may be another one of the important factors;
 3. leakage of the anesthetic agent into the spinal canal may result in false-positive outcomes;
 4. pain provocation does not occur in advanced dessicated discs, as opposed to their findings;
5.  a certain percentage of false-negative FAD proved otherwise by the later successful interbody fusions.

Anesthetic Discography in an 81 years old gentleman. Contrast inside the disc (red arrow).

FAD, like PD has certain limitations. It is a regret that they withdrew the clinical trial. There would have been an interesting and useful (with reservation) report.

P.S. the abbreviation: FAD is an unlucky one, according to urban dictionary: a thing that becomes very popular in a short amount of time, and then is forgotten at about the same speed.

DYNAMIC STABILIZATION?

 DYNAMIC STABILIZATION? 

Dynamic stabilization: A flexible rod in place of a solid metal rod.

 It means: you want to stabilize the lumbar spine (the segment which would have been fused), at the same time, you want to maintain mobilization (of the adjacent normal segment).
 Paradoxical, isn't it? No wonder the US FDA banned this fantastic, heavenly idea: thou shalt not have the best of both worlds.

Dynamic Stabilization:" I am screw, but I have a beautiful, wavy, flexible waist and can do mambo that no other screws can."

FDA: "You look like a screw, taste like a screw, smell like a screw, feel like a screw, so you must be a screw, you have to act like a screw. No mambo here, sorry."  

dynamic stabilization system implanted.

Europeans are more open-minded and optimistic than the die-hard American who can't enjoy the good things in life, as I see it.
 On the other hand, dynamic stabilization of nowadays seems to be a revived zombie (Graf system), or face changing .  

Semi-rigid device. Wider screw holes at each end of the plate which allow motions for upper and lower vertebrae.

The Mother of all Dynamic Stabilization. Graf Device: An elastic band looping around the screws.

  
The basic issue is still there: the pedicle screw. A screw is a screw is a screw. Period.
  Dynamic stabilization is intended to decrease the incidence of adjacent segment disease in which rigid pedicle screw instrumentation is the main culprit. If rigid is bad, then soft must be good, as long as the logic is as such simple. History showed that semi-rigid device failed, Graf system was long gone; are we expecting an almost-doomed-to-fail newly bottled good-old idea to do magic-- surgeons and patients both live happily thereafter forever?
  Screw caused problem cannot be solved by a new screw. In the end, history always repeats itself until we wake up.

脊椎骨釘 (椎弓根螺釘) 疾病 Pedicle Screw Disease

脊椎骨釘 (椎弓根螺釘) 疾病
  脊椎骨釘，是一個繼哈靈頓棒(Harrington rod) 用來矯正脊柱側彎後的偉大創新，它是強有力的脊柱固定物。由於其提供足夠的剛性，脊椎骨釘已成功用於治療脊柱骨折，畸形，脊柱轉移瘤等。脊椎骨釘是治療許多從頸到腰椎的脊椎疾病中不可或缺的武器。

  但不幸的是，脊椎骨釘使用在腰椎退行性疾病卻又是另一回事。此外，在脊椎上安置脊椎骨釘是一個技術熟練上要求度很高的手術，並存有高發生率的併發症(54%)。
讓我們來看看美國FDA(食品藥物管理局) 在1998年對椎弓根螺釘的裁決： ``警告：脊椎骨釘其 安全性和有效性僅適用於 .. ..顯著不穩定的退行性滑脫合併神經損傷，脊椎骨折，脫位，脊柱側彎，脊柱後凸，脊椎腫瘤，和以前的融合術失敗（造成假關節)。其安全性和有效性..使用在其他脊椎疾病時不明。'' ``注意事項：脊椎骨釘 .. ..只能由經專門培訓，有經驗的外科醫生使用.. ..這是一個技術上要求度很高的手術，亦對病人有造成嚴重傷害的風險。''

 今天全球的外科醫生廣泛使用脊椎骨釘，幾乎到一個輕率的程度，特別是在退行性腰椎疾病。 12年後，我們有足夠的研究文獻，來瞭解脊椎骨釘使用於病患，會有發生率高達54％，嚴重程度不一的併發症：
1。深部感染：超過 4％。據一位同仁，他曾在一個大醫院的脊椎部門待過，他說，深部感染發生率約6％，超過文獻的統計報告，有些是災難性的，導致四肢癱瘓或下半身癱瘓，甚至死亡。
2。永久性神經根損傷：2.3％
3。錯位的骨釘：11-20％

4。背部肌肉損傷

5。後期背痛，需要取出骨釘：23％
6。鄰近節段病變，需要再次腰椎手術。 （骨釘上一節之原本正常節段發生病變）：手術五年後發生率為16.5％，十年後發生率升到36.1％，即十年後有三分之一的病人需要再次腰椎手術。
  
另一篇研究發現，使用脊椎骨釘發生有症狀的鄰近節段病變比率較高（12.2-18.5％）；相比較，不使用脊椎骨釘或使用其他類固定物，此群患者，鄰近節段病變的發生率較低（5.2-5.6％）。

左: 經腰椎骨釘固定後深部感染，傷口分離。右: 大量膿液流蓋住神經管。(慈濟陳世豪醫師提供)

62歲女士，經脊椎骨釘固定術後五年，腰 1-2節 發生鄰近節段病變。箭頭顯示不穩定。

70歲男士，因下背痛兩年經脊椎反覆手術四次，包括一次深部感染(腰 2-3節) ，胸12-腰1節發生鄰近節段病變，骨釘全部鬆脫。。

 上面顯示的可怕且嚴峻的科學數據，是否說明我們需要重新考慮審慎使用脊椎骨釘，尤其是用在腰椎退化疾患。

 

Pedicle Screw Disease

  Pedicle screw, one of the great innovations in spinal implants since Harrington rod  for correction of scoliosis. It has been used successfully in treating spinal fracture, deformities, and spinal metastasis, thanks to its provided rigidity.  Pedicle screw is indispensable in some spinal disorders from top to bottom of the spine.

  But unfortunately, its use in lumbar degenerative disorders is anther story. Also, pedicle screw placement is a technically demanding procedure with a high complication rate. Let's take a look at U.S. FDA's ruling of pedicle screw in 1998:

``Warning: The safety and effectiveness of pedicle screw ..only for.. significant mechanical instability...degenerative spondylolisthesis with..neurologic impairment, fracture, dislocation, scoliosis, kyphosis, spinal tumor, and failed previous fusion (pseudarthrosis). The safety and effectiveness..for any other conditions are unknown.'' ``Precaution:..pedicle screw..performed only by experienced..surgeons with specific training..this is a technically demanding procedure presenting a risk of serious injury to the patient.'' 

 Globally, surgeons have used pedicle screw to an extent of indiscretion (excuse me, folks, I am not pointing the finger at you.)  especially at the degenerative lumbar spines.

12 years later, we have enough literature regarding complications of pedicle screw,  of varying severity in 54% of the patients:

1. deep infection: more than 4%. According to my associate, Dr. SH Chen, who once worked at a gigantic spine unit, he said the actual infection rate was around 6%, higher than the reported statistics; some were devastating, resulting in quadriparesis or paraplegia, even death.

2. permanent nerve root Injury: 2.3% . crippled.

3. Misplacement of screw: 11-20% , some were inside the spinal canal.

4. Back muscle injury: weakness of the back.

5. Late backache requiring screw removal: 23%

6. Adjacent segment disease (ASD):  16.5% at five years and 36.1% at ten years, requiring additional surgery.

The rate of symptomatic ASD is higher in patients with transpedicular instrumentation (12.2–18.5%) compared with patients fused with other forms of instrumentation or with no instrumentation (5.2–5.6%)

(Left) Deep infection after pedicle screw fixation, Wound Dehiscence .  Right: Pus flew out flooding all over the dura sac. (Courtesy of Dr. SH Chen)

Angulation of L1-2 level (ASD), fortunately no nerve injury. 62 years lady.

T12-L1 ASD, 70 years old male, crippled, underwent 4 spine surgeries in 2 years, including once for deep infection. T12-L1 ASD, screw penetrating the disc and all screws were loosened.

 

The sad and grim scientific evidences shown above indicate that we need to rethink the use of pedicle screw, particularly in degenerative lumbar vertebrae.

Note: I invented the term: Pedicle Screw Disease, all rights reserved (joke). 

國際脊柱視訊會議，羅馬和台北。後感

台灣一向幾乎是醫療科技產業與技術的淨輸入國，輸出的多是量多價低的醫藥器材的產品，如病床，外國已失專利時效的藥品等。這次國際脊柱視訊會議向歐洲醫生展示的全是台灣本身研發並握有世界專利的脊椎產品與手術概念，其中第一位德國講者是在講她使用台灣出口的脊椎注射器，另兩位國外講者(印尼與香港)亦同，我則是介紹我個人設計的經腰側路腰椎間融合椎籠 。
  林智一先生曾提到要取得台灣衛生署證照的困難與辛酸。幾年的向衛生署的反覆申請與答辯完全沒下文。最後得到衛生署證照是一夕之間，在一經濟部舉辦的發展台灣生物科技研討會上，林智一先生特別向經濟部高級官員抱怨取得台灣衛生署證照的困難。此官員立即找來衛生署商榷，後不旋踵即發放許可證照。
 這讓我想到在台灣申請專利案時我本身的事例 。台灣專利局拿出兩項台灣專利說我的申請案與前二者相似而不欲與給專利。我看過它們提出的兩項台灣專利後發現，怎麼會拿皮球與橘子來比擬? 顯然台灣專利局審查人似未詳查兩者的差異，只注意到都是圓的。再看同一案在歐盟專利局它們的提出疑問就相當切題，並同時幫申請人寫出一兩項專利申請案內未書及，而對申請人有利的專利範圍。日本專利局則是對本國人寬鬆，對外國人極度嚴謹，在在是及時保障其本國人，以取得經濟優勢。
   取得專利與商品化完全是兩回事，再好的專利概念若不能商品化，提升生活上的便利，那不過是一張讓自己高興的證書而已。歐盟專利局亦對專利申請。。。再補上，做工去。。。

Live Lateral fusion Surgery for Malaysian Doctors & XLIF

  The Malaysian doctors encountered some trouble when performing XLIF (NuVasive).  They flied to Taipei and wanted to know what was the difference between XLIF and my designed cage using lateral access.
  They were told by XLIF Co. that stand-alone XLIF cage was effective. Also, by elevating the disc height, posterior spinal stenosis might  be relieved (so called indirect decompression) and no need to do decompression.
 My replies were: 
1. stand-alone cage has been shown that it cannot control extension and rotation. This biomechanical fact has been repeated in several papers, unless XLIF rectangular cage has some secret stabilizing mechanism built-in (a case report of XLIF cage migration).  I am wondering whether NuVasive says the same to all western surgeons including Asian ones.
2. Indirect decompression by using cage to elevate disc height is a wishful thinking. I would like to say that decompression procedure is such a simple job. Why not spend a little time to do it and go home sleep tight? Instead of leaving the decompression to the cage, and worrying about the actual outcome?
  They said it took about an hour to setup the whole operating set including probing the nerves inside the psoas muscle before starting lateral fusion procedure. I was joking that when you finish the setup, I had already left the operating table and sipping a cup of espresso. 
  Even they used neuromonitoring, patients still had paresthesia of the thigh.  Some most recent papers show that there was no safe zone or narrow margin of safety for the nerves when performing trans-psoas approach. The most secure way is to retract the psoas muscle and use the muscle to protect the nerves. 
  I told them my principle: respect the anatomy, don't burn the bridge, you or others may have to go back again.

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.

國際脊柱視訊會議，羅馬和台北，2011年4月16日

2011年4月16日
國際脊柱視訊會議，羅馬和台北， 

 4月16日下午2時至7時（台北時間) (羅馬時間:上午9時至下午2點），我們舉辦了羅馬和台北之間的國際脊柱視訊會議。主辦機構為 MOVINGTECH，這是一個新興的歐洲脊柱產品公司，位於羅馬，意大利。 CEO Diego先生（Diego Pizzicaroli）是一個聰明，幽默，富有雄心，誠實的紳士，連同他的勤奮工作人員: Giuseppe Tricarico 先生，秘書小姐Daniela Pellegrino 等; Sabatino Vittorio 先生因工作疲勞未能參加，很遺憾，祝他早日康復。
  此次五小時的學術脊柱視訊會議圓滿完成。國際與會者來自德國，意大利，印尼，香港和台灣。總共有18個專業醫生; 在歐洲方面（意大利，羅馬)，有15個著名的德國和意大利的教授和脊椎外科醫生參加了會議（他們從德國和意大利不同城市到羅馬）;  在亞洲這一面（台北，台灣），有三個演講者：印尼Bambang Darwano 醫生，香港（William Lu教授，香港大學）和我（瀚群骨科醫療中心）。

印尼醫生Bambang （左)，香港大學盧教授（中），我（右），

，林先生（站立）和他的秘書辛迪。

  本次會議的主題是向歐洲醫生介紹和展示台灣的脊柱新產品：Vessel-X，Vessel-lock，活性骨水泥（以鍶元素為基礎）由台灣林智一先生發展，和我自己設計的腰椎椎間融合器 Latero。 
  第一位發言者是博士Jaqeline Repman（Diego先生的配偶，一個經驗豐富的德國骨科醫生），她敘述使用Vessel-X在治療骨質疏鬆性椎體骨折經驗，Vessel-X有一多孔囊袋以避免骨水泥滲漏造成的神經損傷。我是第二個發言者，介紹Latero的設計概念基於簡單物理學，並與類似產品SynFix（Synthes公司，瑞士）在生物力學測試(由慈濟陳世豪醫師施行) 結果上相比較，與Latero其臨床上用於腰椎融合的表現。印尼Bambang Darwano 醫生談到有關Vessel-lock在穩定和治療因多節骨質疏鬆椎體壓迫性骨折造成脊柱後凸畸形，臨床的滿意結果。盧教授介紹以鍶元素（Sr，與鈣元素幾乎相同）的生物活性水泥，他豐富的動物實驗的研究資料，令人印象深刻 ; 此活性骨泥可以跟人骨相生長，以減少傳統骨水泥（PMMA ，聚甲基丙烯酸甲酯）的缺點與併發症。  
  所有議程都準時開始與結束，就如同在一個正式的國際會議。在問答部分很熱絡，一位德國籍翻譯女士從旁協助。雙方的聲音都能清楚地聽到並回答，無異於我們都坐在同一個房間使用麥克風。 

視頻會議現場一景。該助理：德籍翻譯（中間女士）， MediaPlus兩位女士（左，右）。

  當我們看幾個最常見的脊椎手術種類，椎體成形術 vertebroplasty（或後凸成形術 kyphoplasty)，與腰椎椎間融合術 lumbar interbody fusion，兩者是經常使用的，由於全球老齡化社會。這兩種手術有很多來自不同公司的醫療產品，欲達到同樣的目標: 緩解疼痛，改善生活品質。然而，此兩種手術的併發症並不少見，且可能導致災難性的後果。為了盡量減少併發症和保護病人，新的，安全的，並經證明的醫療產品是醫病兩者的急需。
 本次國際視訊會議展示了新的方法來治療: 骨質疏鬆性的腰椎壓縮性骨折，和腰椎退化疾病需要椎間融合的兩方面新產品。我們都希望將來有更多的視訊會議，在未來繼續作學術溝通和意見交流，在不同的國家同步討論，以節省越洋飛行的費用和時間。 

   最後，我要感謝 Diego 先生與同仁的策劃與辛勞，印尼Bambang Darwano 醫生和香港大學 William Lu教授飛到台北參加此次國際視訊會議會議，與台中慈濟骨科主任陳世豪醫師的加入。 

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.