Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_17_библиотеки_им_акад_М_И_Перельмана
.pdf
Custom/Patient-Specic Total Knee Arthroplasty
https://t.me/medicina_free
379
33
. Fig. 33.1 Preoperative plain radiography
. Fig. 33.2 Preoperative axial CT imaging (representative cuts of distal femur and proximal tibia)
33
https://t.me/medicina_free
380
N. O. Sarpong et al.
. Fig. 33.3 Intraoperative clinical images demonstrating ConforMIS iJigs utilized for femoral preparation
Tip
and femoral osteophytes. Femoral and tibial trials can
then be placed to test the knee for stability throughout
In rare instances, the initial jig may not secure rmly
onto the femur due to uncaptured osteophytes on CT
imaging. In such cases, it is helpful to reference the
iView planning images for proper jig placement.
a range of motion. With the iTotal CR system, there is
no custom jig for the patella and as such, the patella is
prepared using conventional methods.
Once all cuts are made, the bony surfaces are copi-
ously irrigated with pulse lavage.
> The distal femoral cuts should be checked carefully to
conrm planar resections.
Using the previously referenced rotational pin holes from
> Final components are cemented into place using stan-
dard modern cementing technique polymethylmethacrylate (PMMA) bone cement. The authors’ standard
practice is not to inate tourniquet for this step.
the initial custom guides, anterior, posterior, and chamfer
cuts are carried out using additional cutting guides.
> Care should be taken that these guides sit ush along
the cut surfaces of bone.
Tibial preparation is also carried out using a custom
cutting guide that matches the patient’s native tibial
slope, within certain manufacturer specications. The
custom tibial guide is used, and sagittal and coronal
alignment can be conrmed prior to the cut using an
attached alignment rod. Proximal tibial resection is performed, followed by the removal of all peripheral tibial
Tip
Ensure exposed bony surfaces are completely dry
prior to cementation to achieve optimal osteointegration to cancellous bone.
Trial liners are placed while the PMMA is allowed
to polymerize, and is exchanged for the real liner(s)
after any remaining cement particles are removed. Of
note, current custom cruciate-retaining designs feature medial and lateral components with separate
polyethylene inserts, while posterior-stabilized designs
feature a single polyethylene insert.
Custom/Patient-Specic Total Knee Arthroplasty
https://t.me/medicina_free
381
33
. Fig. 33.4 Postoperative plain radiography
Postoperative Course
z
The patient undergoes an uneventful postoperative
course and is discharged to his home on the rst postoperative day after ambulating 600feet with the physical
therapist and navigating stairs. His mechanical alignment is restored to neutral (. Fig.33.4).
33.3 Discussion
As the number of patients undergoing TKA continues
to rise, so will the number of patients dissatised with
their outcomes from the procedure. The arthroplasty literature suggests that residual pain is the leading cause
of patient dissatisfaction following TKA, with approximately 30% of clinically signicant knee pain attributable to implant malalignment (Mahoney and Kinsey
2010). Furthermore, about half of early revision TKA
is related to malalignment, instability, and failure of
xation (Sharkey et al. 2014). Previous studies have
demonstrated that postoperative alignment within 0–3°
of the mechanical axis is recommended (Jeffery et al.
1991). Many attempts have been made by implant com-
panies to improve the accuracy of traditional (i.e., offthe-shelf) TKA implants, however, signicant variations
in bony anatomy, limitations of conventional jigs, and
surgeon error can result in component malpositioning
(Bäthis etal. 2004).
Custom, patient-specic TKA represents a differ-
ent approach to the conventional surgical technique for
knee arthroplasty. Given the substantial variation in
anatomical geometry between patients, some surgeons
theorize that custom implants may be advantageous
when compared with ethnic- or gender-specic TKA
(van den Heever etal. 2012). These techniques aim to
improve postoperative alignment using the patient’s
unique anatomical data from preoperative axial CT or
MRI to create TKA components that are unique to the
patient’s anatomy, which can be implanted using custom
disposable cutting jigs. The iTotal CR and PS systems
available through ConforMIS are examples of modern
custom TKA systems.
Several recent reports have compared this technology
to the traditional TKA systems. It has been hypothesized
that rening implant component design using a custom
TKA philosophy allows for more normal kinematics
than patients undergoing traditional TKA (Zeller etal.
2017). Using state-of-the-art mobile uoroscopy, Zeller
et al. analyzed in vivo tibiofemoral kinematics during
deep knee bend and rising from a seated position for
patients who had undergone custom TKA, compared
to patients with traditional off-the-shelf implants. They
reported that the patients undergoing custom TKA
exhibited greater weight-bearing knee exion, greater
posterior femoral rollback, greater axial rotation, and
minimal liftoff (hence better stability in early to mid-
382
https://t.me/medicina_free
N. O. Sarpong et al.
33
exion) when compared with patients who underwent
traditional TKA.The authors concluded that the custom TKA implant demonstrated kinematics that were
more similar to a normal knee (Zeller etal. 2017).
Another study investigated the accuracy of custom TKA in restoring coronal plane mechanical axis
alignment (Levengood and Dupee 2018). In this study,
Levengood et al. utilized computer-assisted surgery
to objectify the mechanical alignment and reported
that custom TKA implants resulted in perfect neutral
coronal alignment (0°) in 84% of patients, with the
remaining 16% exhibiting postoperative mechanical
alignment within 2° of neutral. They also highlighted
that no patients had postoperative extension decits
(Levengood and Dupee 2018). The authors attributed the increased accuracy to the use of the full-set
of patient- specic jigs with the custom implants, with
each jig custom to the patient, compared to previous
patient-specic instrumentation techniques which utilized a starter jig on the femur and a single starter jig
on the tibia, but all subsequent steps utilized standard
instrumentation.
Another study by Arbab etal. also evaluated postoperative alignment in a retrospective study of patients
undergoing custom (ConforMIS iTotal) compared to
conventional (Triathlon; Stryker, Mahwah, NJ) TKA
(Arbab etal. 2018). They reported that the rate of outliers within 3° of neutral limb alignment was 16% in the
custom TKA cohort and 26% in the conventional TKA
group. They concluded that the custom TKA technique may offer an advantage over conventional TKA
in terms of restoration of the mechanical axis (Arbab
etal. 2018).
> While the aforementioned reports have highlighted
improved overall alignment with custom TKA, there
is a dearth of high-quality evidence on the benets of
custom TKA on clinical functional outcomes and
survivorship.
Tait et al. conducted a multicenter prospective trial
of patients undergoing custom TKA and evaluated
patient-reported outcome measures and adverse events
at midterm (Tait et al. n.d.). They reported that there
were statistically signicant improvements in the average
range of motion, KOOS, and three out of four domains
of the KSS (objective, function, satisfaction), when
compared to preoperative measures. Moreover, they
observed a 3.1% manipulation under anesthesia (MUA)
rate and a 92% and 90% overall satisfaction rate at 1 and
2years, respectively (Tait etal. n.d.). They highlighted
that at 2 years, the observed MUA rate was consistent
with previously published reports of MUA after TKA
(Rubinstein and DeHaan 2010).
The rate of MUA for newer generation custom TKA
was investigated in another prospective study by Kay
etal. (2018), given that previous iterations of the custom prosthesis design had been implicated as a possible
contributor to arthrobrosis (Cates and Schmidt 2009;
Chaudhary et al. 2008). These previous reports had
demonstrated signicantly higher rates of postoperative arthrobrosis and need for MUA versus matched
controls after patient-specic TKA (White and Ranawat
2016). Kay etal. reported a 3.05% rate of MUA with
the second-generation ConforMIS iTotal TKA, which is
also consistent with typical MUA rates reported in the
literature (1.5–6%), regardless of implant design (Kay
etal. 2018). A few more clinical outcome studies after
custom TKA are under way. More recently, internal
data from our institution compared short-term clinical
outcomes of custom versus traditional TKA in a retrospective study (Frederick etal. n.d.). We found that at
3months, patients with a custom TKA experienced statistically betterSF-12 PCS and Knee Society scores when
compared to patients undergoing traditional TKA, but
no signicant difference in SF-12 MCS or WOMAC
scores. Furthermore, at 1year, we observed that custom
TKA patients exhibited superior KSS scores (Frederick
etal. n.d.).
> Although the majority of published studies to date
have highlighted the potential benets of custom
TKA, reports of complications also exist, notably in
earlier generations of custom TKA designs.
In a retrospective study, Meheux et al. compared traditional TKA to an older (ConforMIS iTotal G2) and
newer (ConforMIS iTotal G2 Plus) generation custom
TKA designs (Meheux etal. 2019). The authors highlighted that the use of the older generation design was
discontinued after reports of early failure. They reported
no difference in mechanical axis alignment between
the three cohorts, but did observe that the newer generation custom TKA system had superior KSS scores
compared to the traditional and older generation TKA
systems at all time points. Furthermore, they reported
shorter hospital length of stay and blood loss with the
newer generation compared to the older generation and
traditional TKA systems. The principal nding of their
study, however, was the signicant failure rate in the
older generation (23%) compared to the newer generation (0%) and traditional (3%) TKA designs. The most
common mode of failures in the older generation system were tibial component subsidence and polyethylene
Custom/Patient-Specic Total Knee Arthroplasty
https://t.me/medicina_free
383
33
locking mechanism failure, which were eliminated when
the manufacturer modied the design to the newer generation system (Meheux etal. 2019).
> Later generation custom TKA designs have greatly
reduced the reported early failures, but knee arthroplasty surgeons must still recognize that even these
rened systems are not without limitations and certain patients may not be ideal candidates for this technology.
As these custom TKA systems rely on advanced threedimensional imaging for preoperative planning, the
accuracy of custom jig fabrication may be signicantly
affected in patients with exion contractures greater
than 20° or with previous knee instrumentation, as
these may prevent accurate anatomic knee landmarking planning studies (Nam et al. 2016). Furthermore,
manufacturers recommend against the use of their custom TKA systems in situations of severe (>15°) coronal
alignment, severe instability due to signicant bone loss
and/or the absence of collateral ligament instability, and
metal insensitivity, particularly to nickel (ConforMIS
iTotal G2 Surgical Technique Guide 2015). Additionally, as in traditional TKA systems, careful attention to
the cruciate ligaments is recommended during the preoperative examination to prevent inadvertent implantation of a cruciate-retaining custom implant when a
cruciate- sacricing implant is actually warranted.
> In conclusion, custom TKA has been demonstrated
to improve postoperative lower extremity alignment
and some clinical outcome measures in the few studies that exist to date, and these benets may impact
postoperative resource utilization for patients undergoing TKA.
A recent study by O’Connor etal. compared TKA episode expenditure among Medicare fee-for-service beneciaries who underwent custom versus traditional TKA
(O’Connor and Blau 2019). They reported that the average total episode spending was $1695 less for patients
who underwent custom TKA compared to traditional
TKA, and this was attributable to lower average spending on in-patient, skilled nursing facility, and home
health services. Thus, they concluded that the use of
custom TKA may reduce healthcare spending for those
undergoing TKA (O’Connor and Blau 2019). However,
these results may not necessarily be applicable to the
wider Medicare population undergoing TKA, as it is
possible that new technologies (i.e., custom TKA) are
more likely to be used in the healthier population.
Take-Home Messages
5 Restoration of patient anatomy and normal knee
kinematics is the holy grail in TKA.
5 Custom TKA systems have been shown to improve
lower extremity mechanical alignment when compared to traditional TKA systems.
5 Several studies have demonstrated improved clini-
cal outcomes with custom compared to traditional
TKA systems.
5 Osteophytes should be preserved prior to bony
preparation as they are captured in the preoperative CT scan and accounted for in the patientspecic jigs.
5 In rare instances, custom jigs may not secure rmly
onto the bone due to uncaptured osteophytes on
CT imaging. In such cases, it is helpful to reference
the iView planning images for proper jig placement.
5 The authors’ standard practice is not to inate
tourniquet during cementation of the custom TKA
components.
5 A recent study demonstrated potential economic
savings with the use of custom TKA implants in
the Medicare population.
References
Arbab D, Reimann P, Brucker M, Bouillon B, Lüring C (2018)
Alignment in total knee arthroplasty- A comparison of patient-
specic implants with the conventional technique. Knee 25:882–
887. https://doi.org/10.1016/j.knee.2018.05.017
Bäthis H, Perlick L, Tingart M, Lüring C, Zurakowski D, Grifka
J (2004) Alignment in total knee arthroplasty. A comparison
of computer-assisted surgery with the conventional technique.
J Bone Joint Surg Br 86:682–687. https://doi.org/10.1302/0301- -
620x.86b5.14927
Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron
KDJ (2010) Patient satisfaction after total knee arthroplasty:
who is satised and who is not? Clin Orthop Relat Res 468:57–
63. https://doi.org/10.1007/s11999- 009- 1119- 9
Cates HE, Schmidt JM (2009) Closed manipulation after total knee
arthroplasty: outcome and affecting variables. Orthopedics
32:398. https://doi.org/10.3928/01477447- 20090511- 10
Chaudhary R, Beaupré LA, Johnston DWC (2008) Knee range of
motion during the rst two years after use of posterior cruciate-
stabilizing or posterior cruciate-retaining total knee prostheses.
A randomized clinical trial. J Bone Joint Surg Am 90:2579–2586.
https://doi.org/10.2106/JBJS.G.00995
ConforMIS iTotal G2 Surgical Technique Guide 2015
Frederick J, Jennings E, Geller J, Shah R, Cooper H (n.d.) Custom
individually-made total knee implants are associated with
slightly better improvements in early patient-reported outcomes
Hirschmann MT, Behrend H (2018) Functional knee phenotypes:
a call for a more personalised and individualised approach to
384
https://t.me/medicina_free
N. O. Sarpong et al.
33
total knee arthroplasty? Knee Surg Sports Traumatol Arthrosc
26:2873–2874. https://doi.org/10.1007/s00167- 018- 4973- 8
Jeffery RS, Morris RW, Denham RA (1991) Coronal alignment after
total knee replacement. J Bone Joint Surg Br 73:709–714
Kay A, Kurtz W, Martin G, Huber B, Tait R, Clyburn T (2018)
Manipulation rate is not increased after custom total knee
arthroplasty. Reconstr Rev 8:1–48
Levengood GA, Dupee J (2018) Accuracy of coronal plane mechani-
cal alignment in a custom, individually made total knee replacement with patient-specic instrumentation. J Knee Surg
31:792–796. https://doi.org/10.1055/s- 0037- 1608946
Leyvraz PF, Rakotomanana L (2000) The anatomy and function of
the knee – the quest for the holy grail? J Bone Joint Surg Br
82:1093–1094. https://doi.org/10.1302/0301- 620x.82b8.11656
Mahoney OM, Kinsey T (2010) Overhang of the femoral component
in total knee arthroplasty: risk factors and clinical consequences.
J Bone Joint Surg Am 92:1115–1121. https://doi.org/10.2106/
JBJS.H.00434
Meheux CJ, Park KJ, Clyburn TA (2019) A retrospective study com-
paring a patient-specic design total knee arthroplasty with
an off-the-shelf design: unexpected catastrophic failure seen in
the early patient-specic design. J Am Acad Orthop Surg Glob
Res Rev 3:e10.5435. https://doi.org/10.5435/JAAOSGlobal- D- -
19- 00143
Meier M, Zingde S, Steinert A, Kurtz W, Koeck F, Beckmann J
(2019) What is the possible impact of high variability of distal
femoral geometry on TKA? A CT data analysis of 24,042 knees.
Clin Orthop Relat Res 477:561–570. https://doi.org/10.1097/
CORR.0000000000000611
Nam D, Park A, Stambough JB, Johnson SR, Nunley RM, Barrack
RL (2016) The Mark Coventry Award: custom cutting guides
do not improve total knee arthroplasty clinical outcomes at 2
years followup. Clin Orthop Relat Res 474:40–46. https://doi.
org/10.1007/s11999- 015- 4216- y
O’Connor MI, Blau BE (2019) The economic value of custom versus
off-the-shelf knee implants in medicare fee-for-service benecia-
ries. Am Health Drug Benets 12:66–73
Patil S, Bunn A, Bugbee WD, Colwell CW, D’Lima DD (2015)
Patient-specic implants with custom cutting blocks bet-
ter approximate natural knee kinematics than standard TKA
without custom cutting blocks. Knee 22:624–629. https://doi.
org/10.1016/j.knee.2015.08.002
Rubinstein RA, DeHaan A (2010) The incidence and results of
manipulation after primary total knee arthroplasty. Knee 17:29–
32. https://doi.org/10.1016/j.knee.2009.07.001
Sharkey PF, Lichstein PM, Shen C, Tokarski AT, Parvizi J (2014)
Why are total knee arthroplasties failing today– has anything
changed after 10 years? J Arthroplasty 29:1774–1778. https://
doi.org/10.1016/j.arth.2013.07.024
Tait H, Kurtz W, Clyburn T (n.d.) Outcomes after custom individu-
ally made total knee arthroplasty. ICJR Pan Pacic Congress
2016 Presentation 1632
van den Heever DJ, Scheffer C, Erasmus P, Dillon E (2012) Classication
of gender and race in the distal femur using self organising maps.
Knee 19:488–492. https://doi.org/10.1016/j.knee.2011.06.009
White PB, Ranawat AS (2016) Patient-specic total knees demon-
strate a higher manipulation rate compared to “off-the-shelf
implants”. J Arthroplasty 31:107–111. https://doi.org/10.1016/j.
arth.2015.07.041
Zeller IM, Sharma A, Kurtz WB, Anderle MR, Komistek RD
(2017) Custom versus patient-sized cruciate-retaining total knee
arthroplasty: an invivo kinematics study using mobile uoros-
copy. J Arthroplasty 32:1344–1350. https://doi.org/10.1016/j.
arth.2016.09.034
Alternative Bearings inTotal
https://t.me/medicina_free
Knee Arthroplasty
BrianP.Chalmers andSteveB.Haas
Contents
34.1 Introduction – 386
34.2 Case Example – 386
34.3 Surgical Technique – 387
34.4 Ceramic Bearings – 391
34.5 Metal Allergy – 391
385
34
34.6 Wear Properties – 392
34.7 Clinical Outcomes – 392
References – 393
© The Author(s), under exclusive license to Springer-Verlag GmbH, DE, part of Springer Nature 2022
E. Hansen, K.-D. Kühn (eds.), Essentials of Cemented Knee Arthroplasty,
https://doi.org/10.1007/978-3-662-63113-3_34
386
https://t.me/medicina_free
B. P. Chalmers and S. B. Haas
34
34.1 Introduction
The goal of this chapter is to outline the senior author’s
(SBH) surgical technique in achieving a well- aligned
While there have been a number of technological and
philosophical evolutions in primary total knee arthroplasty (TKA) over the last several decades, the principles remain the same: achieve a well-balanced and
and well-balanced TKA with proper cement technique
with an illustrative case example. Finally, the current literature on alternative bearing surfaces in primary TKA
will be reviewed.
well- aligned TKA with durable xation (Mercuri and
Schwarzkopf 2019; Dennis 1991; Donaldson etal. 2015;
Nikolaou etal. 2014).
> While cementless TKA is becoming more common,
cemented TKA remains the gold standard (Nugent
etal. 2019). Proper and meticulous surgical technique
is essential for achieving these principles, including
proper cementation technique.
34.2 Case Example
Our case example is a 62-year-old male with end-stage
right knee varus degenerative arthritis that has failed a
comprehensive conservative management program and
has been indicated for primary TKA (. Fig. 34.1).
Prior to surgery, we obtain long leg standing radio-
ab c
de
. Fig. 34.1 Full-length standing a, standing AP b and lateral c, PA exion d, and Merchant view e patellar radiographs of the right knee
obtained routinely for preoperative assessment
Alternative Bearings inTotal Knee Arthroplasty
https://t.me/medicina_free
387
34
graphs to assess overall alignment and any pathology
of the contralateral limb or hips (. Fig. 34.1a). We
also obtain an AP, lateral, PA exion, and Merchant
view of the knee as we routinely note signicant posteromedial degenerative, bone-on-bone changes on the
PA exion view (. Fig. 34.1d), more so than the AP
view (. Fig.34.1b). We template our femoral and tibial
cuts on the full-length standing view to better plan our
bony resections. We also template sizes for a posterior
stabilized, oxidized zirconium TKA with calibrated
radiographs in order to better prepare for surgery
(. Fig.34.2).
34.3 Surgical Technique
The senior author has utilized a minimally invasive,
modied mini-midvastus surgical approach that has
been previously reported with excellent results for the
past several decades (Haas etal. 2004, 2006). A medial
release is performed, the extent of which is determined
by the preoperative deformity, and the anterior cruciate
ab
ligament (ACL), posterior cruciate ligament (PCL), and
anterior horn of the lateral meniscus are incised.
After measuring the patellar thickness, a preliminary
ush cut is made to gain exposure and make a at surface for a thin bent Homan to retract upon; in patients
with softer bone or thinner patellae, this step is skipped.
The femoral canal is then accessed with an opening
reamer, starting typically just superior to the origin of
the PCL. After irrigating, an intramedullary guide is
inserted in the femoral canal with a 5° valgus cut angle
planned, variable depending on the patient’s anatomy
on the preoperative long-standing radiograph, and a
9mm resection planned. The angular guide is pinned to
the distal medial femoral condyle (MFC) (and should be
proud on the distal lateral femoral condyle [LFC]) and
the cutting guide is pinned in place with two headless
pins. The distal femoral resection is adjusted with the
guide in order to achieve a bony resection to the trochlear groove. Patients with remaining cartilage may
require a “+2” distal femoral cut, while patients with
distal MFC bone loss, which may be evident as the guide
sitting ush with the LFC, may require an initial “–2”
. Fig. 34.2 Full-length standing a radiograph with the femoral and tibial cuts templated. The component sizes can be accurately templated
on the lateral radiograph b
388
https://t.me/medicina_free
B. P. Chalmers and S. B. Haas
34
cut. After the bony resection, the intramedullary guide
is re-inserted to check the quality of the resection; the
resection is re-visited until the distal angular guide is
ush with the distal femoral resection.
The tibiais then exposed in the normal fashion with
the knee subluxated forward. An extramedullary tibial
cutting guide or accelerometer-based navigation guide is
utilized to cut the tibia at 3° of posterior slope and 90°
to the mechanical axis, referencing the preoperative long
leg template to approximate the depth of the tibial resection medially and laterally. A spacer block with a drop
rod is utilized to ensure that the cut runs along the tibial
crest, in patients with neutral tibial anatomy, and points
to the second ray. The spacer block is then utilized to
balance the knee in extension and check the overall limb
alignment. A drop rod is placed caudad and cephalad in
the spacer block to ensure that the tibial alignment is
neutral and the femoral alignment rod points toward the
femoral head which lies roughly two ngerbreadths
medial to the anterior superior iliac spine (ASIS).
Once satised with the overall alignment and balance in extension, attention is turned to the femur. One
of the most crucial steps in the operation is setting femoral rotation in order to properly balance the knee as
well as ensure proper patellofemoral tracking and
mechanics. The senior author utilizes a medially pivoting sizing guide that allows variable rotation in order to
customize femoral external rotation to a patient’s anatomy. The medial pivot maintains the posterior medial
resection and augments the posterior lateral resection,
rather than a central pivoting guide which would overresect posterior medial bone in order to add femoral
external rotation (Coyle etal. 2019). Whiteside’s line and
the posterior condyles are utilized as a reference to set
femoral external rotation (Poilvache etal. 1996; Arima
etal. 1995; Anouchi etal. 1993). Once rotation is set, the
guide is drilled, the appropriate size is selected with the
sizing guide. The four-in-one cutting block is placed and
the anterior, posterior, anterior chamfer, and posterior
chamfer resections are made.
> Care is taken on the anterior femoral resection in
order to avoid notching the femoral cortex but also to
ensure that the proper size has been selected.
The resection should be close to or right in line with the
cortex in order to avoid overstufng the patellofemoral
joint and ensuring proper posterior offset is restored for
a balanced exion space. With the knee at 90° of exion and with a laminar spreader, the medial and lateral
menisci are removed as well as any posterior osteophytes
that may tension the posterior capsule and affect soft
tissue balancing.
The tibia is then exposed with the knee subluxated
and various sized tibial trays are trialed in proper
external rotation, in line with the medial one-third of
the tibial tubercle, to select the appropriately sized
tibial tray. The senior author utilizes an asymmetric
tibial tray that ts the anatomy of the tibial plateau,
optimizes tibial plateau implant coverage, and allows
proper external rotation of the component without
posterolateral uncoverage (Minoda et al.
2018;
Stulberg and Goyal 2015). Once the size and rotation
are set, the tibial tray is pinned in place and the tibia is
prepared. We utilize the drill initially on forward but
then drill on reverse at the last one-third to compact
the bone distally as a plug for later cementation. In
sclerotic bone, a small saw is utilized prior to impaction of the keel to avoid fracture of the tibial plateau
or shifting of the component position. The keel is then
punched.
The femoral trial is then inserted and the box is prepared. A PS polyethylene trial is inserted and the range
of motion, balance, and alignment are trialed with
various polyethylene thicknesses. Alignment rods are
again utilized to check the femoral, tibial, and overall
limb alignment. If required for proper balance or
alignment, additional tibial or distal femoral resections are performed and the TKA is re-trialed. Finally,
the patella is recut to a straight surface to a level in
which the overall thickness, taking into account the
thickness of the planned polyethylene implant, is similar to the pre- resection thickness of the native patella
as measured previously. The patella is sized with
appropriate medialization of the component to lateralize the patella and ensure proper patellar tracking. The
knee is taken through range of motion to conrm that
the patella tracks centrally without any lateral tilt or
subluxation.
Once satised with the overall TKA balance, alignment, and patellar tracking, the knee is copiously irrigated and the femoral, tibial, and patellar surfaces are
thoroughly dried. Meticulous cement technique is essential for the durability of cemented TKA implants. Drill
holes are made in any sclerotic bone in order to enhance
cement interdigitation. The senior author cements the
tibia, femur, and patella in that order. Cement is mixed
manually in a bowl. Antibiotic cement is not routinely
utilized but reserved for patients at potentially higher
risk of developing a periprosthetic joint infection (PJI)
(obesity, diabetes mellitus, etc.).The tibia is subluxated
and circumferentially exposed. Utilizing high-viscosity
(HV) cement in the early stages, the keel is ngerpressurized (.
Fig. 34.3a) until fat and marrow con-
tents are seen from the tibia guide pins and the tibial
plateau; the prior bone plug created by reverse reaming
assists in creating a plug for pressurization into the tibia.
The tibial plateau is then fully coated with cement, interdigitating the cement with nger pressure into the plateau (. Fig.34.3b).
Соседние файлы в папке Библиотека им академика М.И. Перельмана