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Orthopaedics & Traumatology: Surgery & Research 101 (2015) 17–21

Available online at

ScienceDirectwww.sciencedirect.com

riginal article

wo-level lumbar total disc replacement: Functional outcomes andegmental motion after 4 years

. Trincata,∗,b, G. Edgard-Rosac, G. Genestec, T. Marnayc

Hôpital privé « les Franciscaines », 3, rue Jean-Bouin, 30032 Nîmes, France65, avenue Jean-Jaurès, 30900 Nîmes, FranceClinique du Parc, 50, rue Emile-Combe, 34170 Castelnau-le-Lez, France

a r t i c l e i n f o

rticle history:ccepted 17 October 2014

eywords:otal disc replacementegenerative disc diseaseow-back pain

a b s t r a c t

Introduction: Lumbar total disc replacement is an effective treatment for single-level discogenic lowerback pain. But the replacement of two disc levels is controversial.Hypothesis: Two-level total disc replacement will improve function while preserving spinal motion.Material and methods: A continuous series of 108 patients (51 women, 57 men) surgically treated overtwo levels with the ProDisc-L implant (Synthes Spine) was evaluated retrospectively with an averagefollow-up of 4 years. Ninety-three of these patients were operated for L4/L5 and L5/S1 degenerative discdisease, while 15 were operated for L3/L4 and L4/L5 disease. The procedure was carried out throughthe left retroperitoneal approach in 65 patients, the right retroperitoneal approach in 42 patients andboth approaches in 1 patient. The Oswestry score, lumbar VAS and radicular VAS were used to evaluatefunction. The motion of the prosthetic disc segments was evaluated using Cobb’s method. Data werecollected prospectively in the context of regular patient monitoring. A retrospective analysis was carriedout by an independent examiner.Results: The procedure led to a statistically significant improvement in the functional scores. The motionof the upper disc segment was 9◦ (0◦–19◦) in flexion/extension and 5.5◦ (2◦–12◦) in lateral bending. Itwas 6.2◦ (0◦–14◦) and 1.9◦ (0◦–7◦) at the lower disc segment. The range of motion was similar in L3/L4and L4/L5, but was less in L5/S1. Lack of mobility was not correlated with alterations in the functionaloutcome. The complication rate was 18%.

Discussion: Two-level lumbar disc replacement improves spinal function while preserving its mobility.But this procedure is fraught with risks and must be carried out by a highly-experienced team. A longerfollow-up is needed to evaluate the sustainability of the results and to detect any adjacent segmentdisease. The French National Authority for Health (HAS) has recommended against two-level lumbar discreplacement, so it no longer can be performed in France.

© 2014 Elsevier Masson SAS. All rights reserved.

. Introduction

Single-level lumbar total disc replacement (TDR) has beenhown to be non-inferior to spinal fusion. Its use is generallyccepted in very specific indications [1,2]. But disc replacementt two levels is controversial because of conflicting results [3–8].urrently, a two-level procedure cannot be performed in Franceecause the HAS (French National Authority for Health) has recom-

ended against it. However, TDR has been shown to be non-inferior

o spinal fusion for the treatment of two-level degenerative discisease (DDD), while improving mobility and functional recovery

∗ Corresponding author. Tel.: +04 66 29 54 55; fax: +04 66 38 31 72.E-mail address: sebastien.trincat@yahoo.fr (S. Trincat).

http://dx.doi.org/10.1016/j.otsr.2014.10.014877-0568/© 2014 Elsevier Masson SAS. All rights reserved.

in the short term [9]. The alternative is to use a hybrid construct[10,11] that combines fusion and arthroplasty, with preservationof segmental motion being the theoretical advantage of the latter.

The goal of this study was to evaluate the perioperative com-plications and functional outcomes in patients who had undergonetwo-level lumbar TDR after a minimum follow-up of 2 years. Thespinal segment motion was evaluated at the last follow-up usingradiographs.

2. Material and methods

This was a continuous retrospective study of 150 patients oper-ated for two-level lumbar TDR who were evaluated at least 2 yearsafter the procedure. Of these 150 patients, only those operated atL3/L4 and L4/L5 or L4/L5 and L5/S1 were included. Patients were

1 tology: Surgery & Research 101 (2015) 17–21

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8 S. Trincat et al. / Orthopaedics & Trauma

xcluded from the analysis if they did not have complete and usablereoperative and postoperative clinical and radiological records. Inhe end, the analysis was carried out on 108 patients (57 men, 51omen) having an average age of 46 ± 10 years (range 19–73). The

verage follow-up was 49 months (range 25–63).The surgical indication was established in patients with multi-

evel symptomatic DDD that was resistant to medical treatment orell-conducted rehabilitation and presented Modic 0, 1 or 2 signs

n MRI [12,13], or failing that, a positive lumbar discogram.The procedure was carried out at L4/L5 and L5/S1 in 93 cases

nd at L3/L4 and L4/L5 in 15 cases. It was performed throughhe left retroperitoneal (anterolateral) approach in 65 patients,he right retroperitoneal approach [14] in 42 patients and bothpproaches in 1 patient. The ProDisc-L Total Disc Replacementystem (Synthes Spine, West Chester, PA, USA) was used in allatients. This is a semi-constrained implant consisting of twoobalt-chrome alloy endplates with keels that are coated withorous plasma-sprayed titanium and an UHMWPE core that islipped to the inferior endplate and articulates with the supe-ior endplate through a convex dome. The average duration of therocedure was 111 ± 31 min (70–230) with an average blood lossf 316 ± 453 mL (50–3500). The surgical scar was 10 ± 2 cm (5–18)ong on average.

Data was collected prospectively in the context of regularatient follow-up. The Oswestry Disability Index (ODI) and sev-ral EVA tests (lumbar pain, radicular pain and satisfaction) wereerformed preoperatively and then postoperatively to assess func-ion at 3 months, 6 months, 1 year, 2 years and then every 2 years.adiographic assessment consisted of standard A/P and lateraleight-bearing views, dynamics images (Fig. 1) and standing views

f the entire spinal column. The segmental motion was evaluatedsing Cobb’s method [15].

The data were analysed retrospectively by an observer who wasot affiliated with the surgeons, implant designers and implantanufacturer. Statistical analysis was performed with Statview®

oftware to compare preoperative and postoperative data with Stu-ent’s t-test. Differences were considered significant if P < 0.05.

. Results

Results of the segmental motion analysis are given in Table 1.verall, the two levels remained mobile in flexion/extension and

ateral bending; the range of motion was significantly greater inhe upper segment. Specific analysis of the motion of each type of

onstruct found no differences between the two levels in the L3/L4nd L4/L5 constructs, but significantly lower values in the loweregment of the L4/L5 and L5/S1 constructs. Motion in the L4/L5egment was unaffected by the type of construct used.

able 1ntraprosthetic motion (degrees).

Flexion/extension Lateral bending

Level 1 9 ± 5.7 (0–19) 5.5 ± 3.2 (2–12)Level 2 6.2 ± 4.5 (0–14) 1.9 ± 2.4 (0–7)P < 0.05 < 0.05

L3/L4 8± 5.7 (1–14) 6.9 ± 3.2 (3–10)L4/L5 8 ± 7.0 (1–14) 2.2 ± 3.2 (0–7)P n/s n/s

L4/L5 7.3 ± 8.2 (1–19) 4.3 ± 3.7 (0–8)L5/S1 4.4 ± 5.2 (1–12) 0.75 ± 0.95 (0–2)P < 0.05 < 0.05

L4/L5 (upper level) 8 ± 7.0 (1–14) 2.2 ± 3.2 (0–7)L4/L5 (lower level) 7.3 ± 8.2 (1–19) 4.3 ± 3.7 (0–8)P n/s n/s

/s: not significant.

Fig. 1. A. Dynamic lateral bending X-rays for L4/L5; B. Dynamic flexion/extensionX-rays.

Functionally, there was a significant improvement in the ODI,lumbar VAS and radicular VAS; the satisfaction VAS was 7.9 at thelast follow-up (Table 2, Fig. 2).

If a “mobile segment” is defined as one with more than 2◦

motion, then three types of progression were observed: constructswhere motion was preserved on both levels (74% of cases, including

87% of L4/L5–L5/S1), constructs where motion was preserved in theupper segment (21% of cases) and constructs without any motion(7% of cases). No significant differences were found between these

Table 2Functional results.

Preoperative Last follow-up � P

ODI/50 25 ± 9 12 ± 10 −50% < 0.05Lumbar VAS 7.1 ± 2 2.8 ± 2.4 −60% < 0.05Radicular VAS 5.4 ± 3.1 2.6 ± 3 −52% < 0.05Satisfaction VAS – 7.9 – –

S. Trincat et al. / Orthopaedics & Traumatology: Surgery & Research 101 (2015) 17–21 19

Fig. 2. A. Change in functionnal VAS and patients satisfaction at last follow-up. B.Change in the ODI.

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Table 3Complications.

Implant-related Not implant-related

1 unclipping of polyethylenecore

3 iliac vein wounds2 left common iliac vein wounds (2

L4/L5–L5/S1 using left approach)1 right common iliac vein wound (1

L4/L5–L5/S1 using right approach)2 implant subsidence (superiorendplate of middle vertebra)

4 retroperitoneal hematoma1 L5 radicular deficiency1 dura mater wound

the persistence of pain and stiffness, as mentioned above. But this

TC

Fig. 3. ODI/100, comparison of multilevel (2–3) total disc replacement.

hree groups in terms of the functional outcomes (VAS-L, VAS-Rnd ODI) at the last follow-up (P > 0.05).

The complications are listed in Table 3. There was an 18% com-lication rate (all causes combined) for the entire series, which

ccurred in 15% of patients. Early surgical revision was requiredn 2.8% of patients: one for unclipping of the UHMWPE insert andwo for retroperitoneal hematoma secondary to letting go of vein

able 4omparison of flexion/extension motion at L3/L4, L4/L5, L5/S1 in various published studi

Mobility This study Physiological 1 level

Hayes [16] Frobin [17] Huang [

L3/L4 8◦ 10◦ (2◦–18◦) 14.2◦ (± 3.7) 7.5◦ (3◦–L4/L5 8.8◦ 13◦ (2◦–20◦) 16.4◦ (± 4.1) 6.2◦ (2◦–L5/S1 4.5◦ 14◦ (2◦–27◦) 13.2◦ (± 6.1) 4.1◦ (2◦–

2 deep vein thrombosis1 wound dehiscence5 urinary infection

sutures or ligatures. No late revisions were needed during thefollow-up period.

4. Discussion

This study is the first to evaluate the motion of a two-level lum-bar disc replacement construct. It confirms that motion is preservedin the two segments after more than 4 years of follow-up and thatfunctional outcomes are good. The major strength of this study liesin the large number of patients included. The retrospective natureof the study and the inability to process all the radiographic recordsreduces its impact however.

The theoretical amplitude of implant motion is 20◦ in flex-ion/extension and bending [3]. The true range of motion observedin vivo is lower because of the presence of muscle, capsule and lig-ament structures. It is also lower than physiological values [16,17],amounting to 75% at L3/L4, 50% at L4/L5 and 33% at L5/S1 [17].Leivseth [18] reported similar findings of 66% of the physiologicalvalues at L3/L4, 45% at L4/L5 and 27% at L5/S1 [17,19]. This phe-nomenon can be explained by the persistence of pain, apprehensionon the part of the patient and presence of tissue retractions [18].

However, the motion values were near those observed at onelevel with the same implant [3,15,18] (Table 4). The average motionof the CharitéTM Artificial Disc (DePuy Spine, Inc., Raynham, MA,USA) was 7.5◦ in flexion/extension after two years [20]. The motionis less at L5/S1 in comparison to L3/L4 and L4/L5 [3,15,18], likelybecause of interlocking. At this point, no study has compared themotion of hybrid constructs and two-level disc replacement con-structs.

Although the outcomes were positive and motion was pre-served, in some patients the replacement disc was completelyfrozen and did not move at one or both levels. This can be explainedby various factors [18]. First, the mobility of an implant is related tothe quality of its positioning, which must be as close as possible tothe vertebra’s instantaneous center of rotation. Non-optimal posi-tioning reduces implant motion, even if it does not necessarily leadto poor functional outcomes [20]. It is also possible that excessivedisc height has a negative effect of mobility because of the result-ing distraction. This phenomenon can also be explained clinically by

stiffness does not seem to be correlated to the functional outcome.Figs. 3 and 4 compare the functional results reported in stud-

ies of multilevel disc replacement [3,4,6,8]. The improvement was

es.

2 levels Hybrid

15] Leivseth [18] Tropiano [3]

12◦) 8.0◦ (± 5.5◦) – – –18◦) 8.0◦ (± 3.9◦) 10◦ (8◦–18◦) – –10◦) 3.5◦ (± 4.1◦) 8◦ (2–12◦) – –

20 S. Trincat et al. / Orthopaedics & Traumatology: Surgery & Research 101 (2015) 17–21

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Fig. 5. Functional outcomes; comparison to hybrid constructs. A. ODI; B. RadicularVAS; C. Lumbar VAS.

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Fig. 4. VAS/10, comparison of multilevel (2–3) total disc replacement.

omparable both in terms of the ODI (Fig. 3) and the VAS (Fig. 4),ut the small number of patients in some of these studies tempershe interpretation of these results. Only one study provides similarnformation for hybrid constructs [10]. Despite the use of differentonstructs, the ODI and lumbar VAS were decreased by 53% and 65%,espectively, after 2 years of follow-up, which was comparable tohe results of the current study (Fig. 5).

Several authors have highlighted the biomechanical risks ofultilevel TDR. Huang [15] reported a 24% rate of junctional

egeneration with hypomobility. It also seems that these implantsncrease the pressure on the posterior facet joints [4,21–23], whichan eventually lead to symptomatic lumbar facet arthropathy. Mul-ilevel constructs can also be the source of coronal plane deformity24].

The rate of early complications related to the implant or theurgery in the current study (Table 5) was similar to other serieseporting results with multilevel implants [4,6,8] (Fig. 6).

Surgically, the main intra-operative risk revolves around theliac and iliolumbar veins; damaging them can cause potentiallyife-threatening bleeding. This risk justifies having a vascularurgeon present in the ward or operating room. Performing preop-rative CT angiography can help to identify the bifurcation level orook for any anatomical variations. These venous wounds are also aostoperative risk with the possibility of retroperitoneal hematomaecondary to vein suture dehiscence or deep venous thrombosisecondary to the compression applied during repair.

As for implant-related complications, two cases of superior end-

late compression occurred in patients above 60 years of age withsteoporotic bone for which the TDR indication was debatable.steoporosis should be a contraindication and preoperative DEXA

able 5omparison of complications with multilevel implants.

Current study Siepe, Spine 2007 Hannibal, Spine 2007 Bertaglioni, Spine 2005

Implant ProDisc ProDisc ProDisc ProDisc

Levels 93 L4/L5 + L5/S1 20 L4/L5 + L5/S1 29 L4/L5 + L5/S1 15 @ 2 levels15 L3/L4 + L4/L5 3 L3/L4 + L4/L5 10 @ 3 levels

Complications 18% 30% 19% 16%3 iliac vein wounds 1 hypogastric plexus 1 left EIV thrombosis 1 implant subsidence4 retroperitoneal hematomas 1 segmental stenosis 2 foot drops 1 PE core dislocation1 L5 radicular deficiency 1 L2/L3 L3/L4 hernia 1 femoral artery

thrombosis1 wound dehiscence

1 dura mater wound 1 wound dehiscence 1 L3/L4 hernia 1 retrograde ejection2 deep vein thrombosis 1 retroperitoneal seroma 1 L5 vertebra fracture1 wound dehiscence 1 posterior facet arthropathy5 urinary infections1 unclipping of PE core2 implant subsidences

S. Trincat et al. / Orthopaedics & Traumatology

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[24] Ching AC, Birkenmaier C, Hart RA. Short segment coronal plane deformity after

Fig. 6. Complication rate for multilevel implants.

can should be considered before the surgical procedure. Vertebralracture can theoretically occur in the middle vertebra because ofhe keels [3,25]. No fractures were observed in the current study.ther rarer complications were observed such as dislocation of theolyethylene core [8] and implant migration [7].

Because of current health regulations in France, two-level totalisc replacement can no longer be performed. As a consequence, were exploring the possibility of using hybrid constructs in patientsith multilevel degenerative disc disease.

. Conclusions

Two-level total lumbar disc replacement resulted in satisfactoryunctional outcomes, while preserving motion in the operated seg-

ent in most patients. The range of motion was similar at L3/L4 and4/L5, but was less at L5/S1. The absence of motion in one or evenwo levels was not correlated with poorer functional outcomes.

But this procedure is not devoid of perioperative risk, especiallyascular ones; it should be performed by teams that are well-versedn the surgical technique, potentially in collaboration with a vascu-ar surgeon.

A prospective randomised study is needed to properly compareultilevel TDR with hybrid constructs. However, multilevel degen-

rative disc disease is a contraindication to arthroplasty in Franceecause of the HAS recommendations.

A medium-term analysis of the current study population will beeeded to re-evaluate the segmental motion and detect any adja-ent segment disease. Additional evaluation of the sagittal balancend segmental lordosis correlated with the functional outcomesould also help us better define the indications and identify riskactors for poor functional outcomes.

isclosure of interest

TM: Clinical trials: principal investigator, study coordinator andrimary researcher for ProDisc-L (Synthes Spine, West Chester, PA,SA).

GG: Clinical trials: co-investigator, non-primary researcher forroDisc-L (Synthes Spine, West Chester, PA, USA).

S. Trincat and G. Edgard-Rosa declare that they have no conflictsf interest concerning this article.

cknowledgements

Nathalie Larive, Clinical Research Associate, Clinique du Parc,astelnau-le-Lez, France.

[

: Surgery & Research 101 (2015) 17–21 21

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