There has been a resurgence
of interest in unicompartmental knee arthroplasty (UKA) for
treatment of medial unicompartmental knee osteoarthritis (OA).
Improved prosthetic design, minimally invasive surgical
techniques, and strict patient selection criteria have resulted
in improved survivorship and functional outcomes. A review of
orthopedic literature was conducted regarding the advantages of
UKA versus total knee arthroplasty (TKA); UKA indications;
survivorship; conversion of UKA to TKA; rehabilitation and
outcomes. The UKA appears to be a viable option for patients
with knee medial compartment OA, including younger and active
patients. Survivorship rates of 94% to 97% at 10 years have been
reported.
A dramatic increase
in the prevalence of osteoarthritis in adults 18 years and older
is expected from 2005 to 2030. According to the Centers for
Disease Control and Prevention, the prevalence of
doctor-diagnosed arthritis is projected to increase from the
current 46 million to nearly 67 million by the year 2030.
Approximately 9.3% of the adult population, 25 million people,
are projected to report activity limitations due to arthritis.
According to the report, working-age adults (45-64 years of age)
will account for almost one-third of the cases.1
The authors of a study of knee osteoarthritis and primary care
physician’s diagnoses, report that the prevalence of painful
disabling knee osteoarthritis in the general population aged
> 45 years is 12.5%.2 The
current management of this problem consumes a significant
portion of health care resources, and the estimated increase
poses a major challenge to the health care system. Prevention,
life-style changes, and disease self-management may help reduce
the burden, however the primary course of management has been
medical. Analgesics for pain relief, braces and orthoses for
load redistribution, exercises to maintain function,
viscosupplemention, and nutritional supplements such as
glucosamine and chondroitin sulfate make up the main thrust of
medical management. Surgical intervention is reserved as a last
resort option when pain becomes debilitating and function is
impaired.1,3
Surgical replacement of the knee improves function by decreasing
pain and reducing deformity. Total knee arthroplasty (TKA) has
long been considered the gold standard for management of
advanced osteoarthritis of the knee. Unicompartmental knee
arthroplasty (UKA) was first introduced in 1973 by Leonard
Marmor4, but did not gain wide
acceptance due to poor early results, high failure rates, and
technical demands of the procedure.5,6
The causes of early failure are multifactorial and include poor
patient selection and surgical technique,3-5,7
inadequate implant design,8
polyethylene wear,9 and poor
understanding of knee kinematics and alignment influences.10,11
A resurgence of interest in the UKA is due in part to improved
devices, surgical technique, survivorship results, and new
minimally invasive techniques.12-14
In a review of literature of unicompartmental knee replacement,
Bert15 concludes that UKA is a
successful procedure in a moderately active older patient
population with only unicompartmental knee pain. The author
further states the importance of strict patient selection
criteria, and that the patient should understand the prosthetic
device will not last forever.15
Improved mid and long term results of the UKA, comparable with
the excellent and well-known results after TKA, have contributed
to the use of UKA on the younger, the active, and the obese
population.12-14,16-19
According to the Millennium Research Group’s US markets for
reconstructive devices 2001 and 2002, as cited in Springer et al6
and Naal et al12, 2500 UKAs
were performed in the United States in 1996 and 1997, making up
approximately 1% of all knee arthroplasties. In 2000 and 2001
this proportion increased to 6%, or 33,900 UKA procedures.6,12
ADVANTAGES OF UKA VS TKA
In
a review by Satku3 of UKA as a
surgical option, arthritis was predominately in one compartment
in 5% to 20% of patients who underwent TKA. According to Marmor4
it is illogical and contrary to basic orthopedic principles to
remove and replace an entire structure if only one portion is
damaged. A revision may be required in the future, but
preservation of the normal structures should be pursued whenever
possible.4 The advantages of
the UKA over the TKA include a preservation of bone stock,
maintenance of more normal joint kinematics due to ACL sparing
techniques, better proprioception, better ROM, and faster
recovery.20 Meek et al21
report that a possible advantage of the UKA is the ability to
convert a failed UKA to TKA, thereby delaying the eventual TKA
by up to a decade. White et al22
notes that timely replacement of the deteriorating medial
compartment with varus correction, before the cruciate ligament
has stretched, may prevent lateral compartment breakdown. Recent
advances in minimally invasive surgical techniques have also
helped renew the interest in the UKA. Smaller incisions, limited
quadriceps disruption, decrease in morbidity, and decreased
rehabilitation time are all benefits of the minimally invasive
technique.18 The use of UKA,
particularly the minimally invasive technique, has also
increased in the younger active population as an alternative to
high tibial osteotomy.20,23 In
a cost-effectiveness analysis between UKA and TKA procedures for
unicompartmental knee osteoarthritis, the authors report that
the UKA procedure is more cost effective over the TKA if
survival rates are a minimum of 12 years.24
INDICATIONS
Restoration of
function and relief of pain that interferes with the patient’s
quality of life is the primary indication for knee arthroplasty.4,12
For the UKA it is pain localized to one compartment with
corresponding radiographic evidence of unicompartmental disease.25
Resurfacing only the involved portion of the knee with
degenerative changes is the basic premise of a UKA. This allows
the relatively normal articular structures to remain intact.5
It is generally accepted that surgical outcomes improve when
careful patient selection criteria are followed. In an early
study by Kozinn and Scott,26
they reported that unicondylar knee arthroplasty is a useful and
reliable alternative for the treatment of unicompartmental
degeneration of the knee in selected patients. They suggest the
following parameters for the best patient selection criteria:
age 60 or more; weight less than 82 kg (180 lbs); low activity
level; no pain at rest (pain at rest may indicate inflammatory
component to disease); pre-operative range of movement of 90
degrees with 5 degrees or less flexion contracture; and angular
deformity of the knee should be less than 15 degrees and
passively correctable. Several other authors have used these
parameters for patient selection guidelines in their research of
UKA surgical outcomes.7,12
Since the introduction of the UKA, many improvements have been
made in prosthesis design and less invasive surgical techniques,
and good long-term results have been reported.27,28
Swienckowski and Pennington13
reported on surgical technique of the UKA in patients sixty
years of age or younger and concluded that UKA was associated
with pain relief and excellent function in a younger, active
patient population. The authors’ criteria for inclusion were:
noninflammatory unicompartmental arthritis; contained mature
osteonecrosis; at least 90 degrees of knee flexion; an intact
anterior cruciate ligament; a flexion contracture of less than
10 degrees; maximum varus or valgus < 20 degrees that can be
passively corrected to five to seven degrees of valgus with the
knee in maximally allowed extension; outerbridge changes no
greater than grade I or II in the opposite compartment or the
patellofemoral articulation; and no age restriction if otherwise
qualified, refractory to conservative care.
According to a review of the literature by Engh and Ammeen,29
unicompartmental knee arthroplasty is not recommended for
patients with an ACL-deficient knee and a history of instability
due to high failure rates from polyethylene wear. The authors
examined 4 device types, both fixed and mobile bearing devices,
and concluded that the increased sliding motion caused by the
deficient ACL ligament lead to accelerated polyethylene wear.
Tabor et al14 reported on the
long-term outcomes of UKA and concluded that age less than 60
and obesity do not appear to be contraindications to the
procedure. Kort et al18 also
found that UKA was an important option for patients 60 years or
younger, but reported that obesity was a contraindication to the
procedure due to technical difficulties, risk of complications,
and early failure rates. In a review of the Finnish Arthroplasty
Register as much as 25% of all UKAs were implanted in patients
aged between 50 and 59 years.30
The authors concluded that younger patients (< 65 years)
were at a 1.5 fold increased risk of revision compared to older
patients (> 65 years).
SURVIVORSHIP
Failures of the UKA have many causes. In a retrospective study
of UKA device types and survival rates, the authors reported ten
year survival rates ranging from 81% to 53% when comparing four
device types: the Oxford meniscal bearing unicondylar (81%); the
Miller-Gallante II unicondylar (79%); the Duracon (78%); and the
PCA (53%).30 Naudie et al28
reported 94% and 90% respectively on five and ten year survival
rates of the Miller-Gallante device. Additionally, Argenson27
reports 10 year survival rates of the Miller-Gallante UKA to be
94%. In an early study evaluating the efficacy of an uncemented
UKA prosthesis, Bernasek et al8
concluded that this prosthetic design was prone to loosening,
persistent pain, and high failure rate (39%). In a matched study
of UKA and TKA patients, survivorship rates at five years were
reported to be far superior for the TKA patients (100%) compared
with the UKA patients (88%).31
The two groups were matched for age, gender, body mass index,
pre-operative active range of motion and pre-operative Knee
Society scores.31 Excellent
survivorship results of 95.7% at 15 years were reported by
Berger et al7 in their
prospective study of 59 patients with medial unicompartmental
arthroplasty of the knee. The authors noted progressive
patellofemoral arthritis was the primary mode of failure despite
the pristine appearance of the patellofemoral articulation at
the time of the initial procedure. Murray et al32
reported on the ten year survival rates of the Oxford medial
unicompartmental arthroplasty using the fully congruous mobile
polyethylene bearings. These authors reported excellent
survivorship results of 97%, with no failures due to
polyethylene wear or aseptic loosening of the tibial component.
The authors felt that their high success rate was due to strict
patient selection criteria, and that the surgical team had
previous experience with meniscal bearings before starting
unicompartmental knee replacement.32
Alignment has been cited by numerous authors as an important
prognostic factor in the survival of UKA.9-11,33
Limb alignment affects not only the wear of the unreplaced
compartment, but also the polyethylene of the resurfaced
compartment. Hernigou and Deschamps10
found an increased risk of degenerative changes in the opposite
compartment when there was an overcorrection in valgus of the
preoperative deformity (hip-knee-ankle angle >180 deg). Severe
undercorrection of the varus deformity (hip-knee-ankle angle
<170 deg) was associated with increased polyethylene wear in the
tibial component and recurrence of the deformity.10
Engh et al33
noted that polyethylene wear will increase with time as well as
with the weight and activity level of the patient. In their
study of polyethylene wear in TKA and UKA, the authors found
that malalignment or malposition of a unicompartmental implant
may lead to damaging wear patterns and rapidly destroy the
polyethylene.33 Kasodekar et
al11 report on radiographic
alignment and a four year survival rate of 91.7%, and concluded
that long-term outcomes of UKA are influenced by positioning and
alignment of the prosthesis. Swienckowski and Page9
reported a direct relationship between placement of the tibial
component and clinical results, finding that 90 degree placement
in the coronal plane and 80 degree placement in the sagittal
plane had the best clinical results.
Age has been implicated as a factor in outcomes and survivorship
of knee arthroplasties by many authors.14,17,18,30
In a study of the Oxford phase III unicompartmental knee
replacement in patients under 60 years of age, Kort et al18
concluded that age 60 or younger was not a contraindication to
the procedure. Tabor and his colleagues14
found that there was no significant difference in survivorship
based on age over or under 60 at the time of surgery. Cartier et
al34 reported that the ten year
follow-up results of UKA surgery were no worse for the younger
patients than the older patients, with average survivorship
rates of 93%. In a study of patients sixty years of age or
younger and physically active, Swienckowski and Pennington13
reported excellent results in 93% of their UKA patients at
eleven year follow-up. In a minimum twenty-one year follow-up of
a relatively older age group, O’Rourke et al20
reported that the UKAs in these patients performed well.
Survivorships were reported of 96%, 85%, and 72% at 5, 15, and
25 years respectively. The authors did note that the patients
most at risk for revision were younger than 65 at the time of
surgery.20 The author also
noted that while the younger population may be at greater risk
for revision, the UKA can be an intermediate intervention before
the TKA.20
CONVERSION OF UKA TO TKA
Harryson et al17 found a higher
cumulative revision rate of both UKA and TKA patients under 60
years, but because UKA is less invasive, less costly, has a
lower risk of complication, and has a faster recovery time, the
authors recommend UKA procedures as a good solution for primary
knee arthroplasties only. In a review of converted failed
modern unicompartmental knee arthroplasties to TKAs, Levine et
al5 noted the majority of
failures were due to polyethylene wear. Their data suggest that
failed modern UKA can be successfully converted to TKA. The
authors believe that newer devices and new bone conserving UKA
resurfacing techniques offer favorable conversion results
comparable to primary TKA.5
Johnson et al35 examined the
survivorship of total knee replacements converted from UKAs and
found that the procedure was much less demanding than a revision
of a TKA. The authors concluded that appropriate patients should
be allowed the benefit of a UKA knowing that most offer
excellent long term survival rates, and should a revision be
required, that it can be performed with high expectations that
the outcome will be comparable to an initial TKA in both
function and survivorship.35
Springer et al6 evaluated
conversion of UKA to TKA in a small number of patients (18) and
found that conversion of UKA to TKA took place on average of 100
months (8.3 years) and the most common mode of failure (12
patients) was polyethylene wear. The authors also reported that
conversion arthroplasty did affect knee flexion; pre-operative
average flexion was 113 degrees and post-operative was 111
degrees.6 Several authors have
reported that the conversion of UKA to TKA can be a technically
demanding procedure that depends on how conservative the initial
procedure was and the mode of failure.6,36
In their study, Springer et al6
reported that they encountered bone loss in 77% of the knees at
the time of conversion. Early reports of UKA failures and
difficulty with conversion to TKA occurred due to early (1970s)
non-bone conserving UKA devices and the use of UKA with
rheumatoid arthritis patients. Rheumatoid arthritis patients do
not meet today’s accepted patient selection inclusion criteria
for the UKA device, as outlined by Kozinn and Scott.26
In a ten year follow-up study of UKA surgery, Cartier et al34
reported that UKA revision either to another UKA or a TKA need
not be problematic if a resurfacing UKA is used and failure is
addressed in a timely manner. The Oxford device, with a mobile
bearing, thin polyethylene surface, allows bone preservation of
the medial compartment.36
Saldanha et al36 noted good
short-term results of UKA to TKA revision were based on the
primary UKA device employed.
REHABILITATION &
OUTCOMES
Little is written in the orthopedic literature about
post-surgical rehabilitation following a unicompartmental knee
arthroplasty. Kozin and Scott,26
widely accepted as the pioneers in identifying standard patient
selection criteria, report that care and rehabilitation
following a UKA is similar to that of a TKA. Constant passive
motion may or may not be used, and physical therapy should be
initiated on the first or second postoperative day. Protected
weight bearing and walking should be started as soon as
possible, active assisted muscle strengthening and ROM exercises
should begin on the second postoperative day. Physical therapy
should progress until the patient can actively flex the knee to
90 degrees and independently ascend and descend stairs. These
authors also recommend considering manipulation at 14 days if
ROM goals are not met.26 In a
study of gait and clinical measurements, Borjesson et al37
reported that post-operative rehabilitation started on the day
of surgery with continuous passive motion. Full weight bearing,
active exercise and ADL training was initiated on the first
post-operative day under the supervision of a physical
therapist. After discharge from the hospital, patients were seen
in outpatient rehabilitation 10 times for a program of 10
specific exercises designed to increase ROM of the knee and
muscle endurance of the whole leg.37
Several clinical outcome measurement tools have been described
in the literature for assessing functional improvements
following surgical intervention of the knee. The American Knee
Society Score (KSS)38 is a
clinician-based tool commonly cited in orthopedic literature.
The KSS is divided into separate knee and patient function
scores. The Oxford 12-item knee score39
which is a patient-administered questionnaire that is short,
valid, reliable, and designed specifically for use with knee
surgery. Kleijn et al40
reported on the performance based knee test, the Dynasport ®
Knee Test, which is an accelerometer-based system that
objectively measures functional aspects of gait during various
tasks of daily life. The authors report that the younger, more
active patient values functional improvement more than clinician
based scores, and that the Dynasport Knee Test was able to more
accurately account for higher knee flexion range of motion and
the impact on functional recovery.40
ROM
In a matched study comparing results of UKA versus TKA
outcomes in active ROM, Knee Society Score, and survivorship
rates, the authors reported better ROM with the UKA patients
(mean ROM at 5 years = 104 degrees), but no difference in
clinical outcomes based on the KSS at 6, 18, 36, and 60 months
post-operatively.31 Naudie et
al,28 reporting on UKA with the
Miller-Galante prosthesis, found improved KSS knee and function
scores, and an average ROM of 125 degrees (range = 95 to 145
degrees) at five and ten year follow-up. Kasodekar et al11
reported favorable mid-term results of the UKA with improved
knee and function scores (KSS), and average ROM improvements
from 121.9 degrees to 133.8 degrees. In patients less than 60
years of age with UKA, Kort et al18
reported post-operative knee flexion average ROM was 125
degrees. In a study of patients managed with a modern
unicompartmental arthroplasty that was cemented and performed
with instrumentation and a metal-backed prosthesis comparable to
that used for total knee arthroplasty, the average arc of
flexion was 128 degrees.27
Function: gait,
kneeling, stairs
Restoration of
function is a primary goal of knee arthroplasty. ADL function
includes walking, stair climbing, sit-to-stand ability, and
kneeling. Typical knee flexion angles of 50-60 degrees are seen
during stair climbing, and as much as 90-120 degrees when rising
from a chair.41 In a study of
functional improvements after unicompartmental knee replacement,
Kleijn et al40 found that
functional recovery continues beyond 6 months and even up to two
years. They reported that the average knee flexion ROM leveled
off at one year at 120.5 + 11.7, but that quadriceps
muscle recovery may take longer to recover due to pre-operative
atrophy secondary to osteoarthritis.40
In a study of gait and clinical measurements in knee
osteoarthritis patients after surgery, UKA patients at one year
post-operative reported no pain with walking, had an average of
-3/121 passive knee extension and flexion, and participated in
moderate physical activity.37
The authors also noted that the UKA patients increased their
walking speed the way healthy people do, which is by increasing
both step frequency and step length for both legs.
In
a study comparing three types of knee surgeries and
post-operative kneeling ability and the ability to descend
stairs, the UKA patients performed better than the TKA and
patellofemoral replacement (PFR) patients at one year.42
Kneeling ability was difficult and painful for most patients
pre-operatively with 80-85% of patients reporting it was
impossible or extremely difficult to kneel. It continued to be
challenging for all the groups post-operatively in this study,
with 23% of UKA patients reporting easy or little difficulty
kneeling versus 15% of TKA patients. Stair climbing ability was
significantly better for the UKA group at one year, with
approximately 86% of the patients reporting easy or little
difficulty with descending stairs versus 70% for TKA.42
Weale and colleagues23 reported
on 31 UKA patients compared with 130 TKA patients and found that
the UKA patients were better able to descend stairs and slightly
better at kneeling than the TKA patients, but the patient’s
perceptions of functional outcome, based on the Oxford 12-item
knee questionnaire, showed the results from the Oxford UKA were
no better than those from AGC total knee replacement.
Proprioception &
Kinematics
It
is generally accepted that tricompartmental total knee
arthroplasty significantly alters the kinematics of the knee.
Engh and Ammeen29 report that
evidence from laboratory studies of gait analysis, video
fluoroscopy, and implant retrieval analysis indicate that TKA
motion patterns across the articular surface is very different
compared to the healthy, ACL-intact knee. One of the noted
benefits of UKA is the preservation of the patellofemoral joint,
the anterior cruciate and posterior cruciate ligaments,
meniscus, and articular cartilage of the unaffected compartment,
thereby retaining normal proprioception and kinematics of the
knee.26 In a study of
fixed-bearing unicompartmental design, assessing
closed-kinetic-chain knee kinematics and quadriceps tension,
Patil et al41 report knee
kinematics (rotation and roll) during knee flexion were similar
to an intact knee. These encouraging results of this cadaver
study suggest unicompartmental design may offer the potential to
restore or preserve normal kinematic function better than the
tricompartmental knee replacement. The authors conclude that the
restoration of normal knee function may benefit patient
rehabilitation, extensor function, implant survival, and wear.41
Patient’s Perceptions
There was no difference in patient’s perception of functional
outcomes, using the Oxford knee score, between UKA and TKA
patients, however patients receiving unicompartmental
replacement were better able to descend stairs and had slightly
better ability to kneel.23 In
contrast, Walton et al19 found
a significant difference between the Oxford knee score of
patient’s perceived functional improvement between TKA and
patients with the minimally invasive UKA. They also found UKA
patients were significantly more likely to return to or increase
their level of sporting activity postoperatively than TKA
patients. These authors also universally advised their patients
to cease high-impact activities such as jogging.19
Return to Sport
Several authors have noted their concerns over patients
returning to physical activity following a joint replacement,
and that it must be balanced out by the potential overall health
benefits of exercise on cardiovascular, metabolic, and
musculoskeletal systems.12,16,43-45
Many studies examining physical activity and sports after joint
replacement have reported on TKA only,43-45
and some highlights are reported here. Due to the biomechanical
differences between the TKA and UKA, we can not simply transfer
TKA recommendations to the UKA patient. Several TKA studies
have been referenced for general information and background.
In
a review of current literature and exercise recommendations
after total joint replacement, it is generally advised to avoid
jogging, tennis, and running sports due to concerns that these
activities cause excessive stress in the polyethylene joint
bearings risking delamination and polyethylene wear, prosthetic
loosening, and increased revision rates.43-45
Loads during these high impact activities can reach up to 8-10
times body weight (BW), with running at 16km/hr reaching 14 BW.44,45
The peak loads of these activities generally occur between 40
and 60 degrees of knee flexion, where many of the modern TKA
designs do not have high conformity, and which the contact area
is stressed beyond the yield point.44
Walking, swimming, and cycling are exercise activities that are
generally accepted and encouraged activities after TKA.43-45
Cycling peak loads were found at approximately 80 degrees of
flexion, but the tibiofemoral load is approximately 1.2 BW and
therefore not overly stressful on the implant. Tibiofemoral peak
loads during power walking can reach up to 4 BW at 20 degrees of
flexion, but because at that ROM a mobile bearing prosthetic
design demonstrates near conformity, the stresses never exceed
the yield point of the polyethylene.44
In a retrospective review of participation in sports after total
knee replacement, Bradbury et al43
reports 65% of patients that participated in sports before
surgery returned to regular sports after surgery. The authors
also report that the patients were more likely to return (91%)
to low-impact activities such as lawn bowling, than high-impact
activities such as tennis (20% returned). In a literature
review of exercise recommendations after total joint
replacement, Kuster45 notes
that patients should be encouraged to be physically active after
a total joint replacement; that the wear on the prosthesis is a
function of how it is used and not time. Further, exercise
increases muscle strength and coordination (reduces risk of
falls); and improves prosthetic fixation; and that even high
impact activities (hiking, skiing, tennis) may be performed on
an occasional basis but not used for regular endurance exercise.
UKA has been gaining in popularity, and a younger, more active
patient population has been undergoing the surgery. There is,
however, a lack of literature regarding sporting activities
following a UKA procedure. Walton et al19
compared TKA and UKA patients on return to sport and work, and
found that UKA patients were significantly (P = .0003)
more likely to increase or maintain their pre-operative level of
sporting activity following surgery than TKA. Fisher at al16
looked at sporting and physical activity following Oxford medial
unicompartmental knee arthroplasty, and reported 93% of patients
were able to return to their regular sporting or physical
activity following surgery. The two main activities were
swimming and golf, with approximately 35% of the patients
returning to cycling, dancing, hiking, or lawn bowling. Three
patients also returned to gym, squash, and jogging. This is a
higher rate of return to sporting activities than previously
reported for TKA (65%),43 and
the authors attribute that to the Oxford UKA device, which
functions mechanically in a more physiological manner than the
TKA.16
A
study by Naal and his colleagues12
in the American Journal of Sports Medicine evaluated the return
to sports and recreational activity in a mostly Swiss patient
population after unicompartmental knee arthroplasty. They found
that the vast majority of UKA patients were able to return to
sports and recreational activity. In their study, these authors
demonstrated a return to activity rate after UKA of about 95%,
which is better than rates after TKA. Ninety percent of these
patients stated that surgery had maintained or improved their
ability to participate in sports. The top five sports that the
patients (men, women, older than 66 years, under 66 years)
participated in were hiking, cycling, swimming, downhill skiing,
and exercise walking (5% of the younger group played tennis).
Hiking and cycling were the most common sports, with
approximately 51% of patients participating in one of the two
activities.12 The vast
majority of patients treated with UKA in this study were very
active and they were able to return to sports and recreation
following surgery. The authors note that the primary indication
for knee arthroplasty is still pain relief and improved
function, but that patient’s expectations are rising regarding
the return to unrestricted daily activities and the restoration
of the ability to participate in sports. At times these
expectations are unrealistically high, and prosthetic wear
remains a major concern for long-term implant survival. In this
current study, the follow-up period of 1-2 years is too short to
formulate a valid conclusion regarding prosthetic wear and
loosening in physically active patients after UKA.12
Conclusion :
A
resurgence in the UKA since Marmor’s first procedure in the
1970’s has occurred due to improved surgical technology,
improved devices, and minimally invasive procedures. UKA
appears to be a viable option for patients with osteoarthritis
of the knee that involves only the medial compartment, including
the younger and the more active patients. Excellent survivorship
rates of 94% to 97% at 10 years have been reported in the
literature. While the younger patient may require a second
surgery in their lifetime, the conversion from the modern UKA to
a TKA can be performed with minimal technical difficulties, and
the patient can have high expectations for optimal outcomes.
Functional outcomes (stairs, gait, kneeling) are better and
return to physical activity more likely for the UKA patient than
the TKA patient. It is unanimous amongst the reviewed authors
that high impact running activities should be avoided for a
joint replaced knee.
Reference :
1.Hootman JM, Helmick CG. Projections of US
prevalence of arthritis and associated activities
limitations. Arthritis & Rheumatism. 2006 Jan;54(1):226-229.
2.Bedson J, Jordon K, Croft P. The prevalence and history of
knee osteoarthritis in general practice: a case-control study.
Family Practice. 2004;21:1-6.
3.Satku K. Unicompartmental knee arthroplasty:Is it a step in
the right direction? Surgical options for osteoarthritis of the
knee. Singapore Med J. 2003;44(11):554-556.
4.Marmor L. Unicompartmental knee arthroplasty: ten to 13 year
follow-up study. Clin Orthop Relat Res. 1988;226:14-20.
5.Levine WN, Ozuna RM, Scott RD, Thornhill TS. Conversion of
failed modern unicompartmental arthroplasty to total knee
arthroplasty. J Arthroplasty. 1996;11(7):797-801.
6.Springer BD, Scott RD, Thornhill TS. Conversion of failed
unicompartmental knee arthroplasty to TKA. Clin Orthop Rel Res.
2006;446:214-220.
7.Berger RA, Meneghini RM, Sheinkop MB, Della Valle CJ, Jacobs
JJ, Rosenberg AG, Galante JO. The progression of patellofemoral
arthrosis after medial unicompartmental replacement. Results at
11 to 15 years. Clin Orthop Rel Res. 2004;428:92-99.
8.Bernasek TL, Rand JA, Bryan RS. Unicompartmental porous coated
anatomic total knee arthroplasty. Clin Orthop Relat Res. 1988
Nov;236:52-59.
9.Swienckowski J, Page BJ. Medial unicompartmental arthroplasty
of the knee. Use of the L-cut and comparison with the tibial
inset method. Clin Orthop Relat Res. 1989 Feb;239:161-167.
10.Hernigou P, Deschamps G. Alignment influences wear in the
knee after medial unicompartmental arthroplasty. Clin Orthop Rel
Res. 2004;423:161-165.
11.Kasodekar VB, Yeo SJ, Othman S. Clinical outcome of
unicompartmental knee arthroplasty and influence of alignment on
prosthesis survival rate. Singapore Med J.2006;47(9):796-802.
12.Naal FD, Fischer M, Preuss A, Goldhahn J, von Knoch F, Preiss
S, Munzinger U, Drobny T. Return to sports and recreational
activity after unicompartmental knee arthroplasty. Am J Sports
Med. 2007;35(10):1688-1695.
13.Swienckowski JJ, Pennington DW. Unicompartmental knee
arthroplasty in patients sixty years of age or younger: surgical
technique. J Bone Joint Surg Am. 2004; 86-A Suppl 1,
(pt2):131-42.
14.Tabor OB, Tabor OB, Bernard M, Wan JY. Unicompartmental knee
arthroplasty: long term success in middle-age and obese
patients. J Surg Orthop Adv. 2005;14(2):59-63.
15.Bert JM. Unicompartmental knee replacement. Orthop Clin N Am.
2005 Oct;36(4):513-522.
16.Fisher N, Agarwal M, Reuben SF, Johnson DS, Turner PG.
Sporting and physical activity following Oxford medial
unicompartmental knee arthroplasty. Knee. 2006
Aug;13(4):296-300.
17.Harrysson OL, Robertsson O, Nayfeh JF. Higher cumulative
revision rate of knee arthroplasties in younger patients with
osteoarthritis. Clin Orthop Relat Res. 2004 Apr;(421):162-8.
18.Kort NP, van Raay JJ, van Horn JJ. The Oxford phase III
unicompartmental knee replacement in patients less than 60 years
of age. Knee Surg Sports Traumatol Arthrosc. 2007 Apr;15(4):
356-60.
19.Walton NP, Jahromi I, Lewis PL, Dobson PJ, Angel KR, Campbell
DG. Patient-perceived outcomes and return to sport and work: TKA
versus mini-incision unicompartmental knee arthroplasty. J Knee
Surg. 2006 Apr;19(2):112-6.
20.O’Rourke MR, Gardner JJ, Callaghan JJ, Liu SS, Goetz DD,
Vittetoe DA, Sullivan PM, Johnston RC. The John Insall Award:
Unicompartmental knee replacement. A minimu twenty-one-year
follow-up, end-result study. Clin Orthop Relat Res.
2005;440:27-37.
21.Meek RMD, Masri BA, Duncan CP. Minimally invasive
unicompartmental knee replacement: rationale and correct
indications. Orthop Clin N Am. 2004; 35:191-200.
22.White SH, Ludkowski PF, Goodfellow JW. Anteromedial
osteoarthritis of the knee. J Bone Joint Surg
[Br].1991;73-B:582-586.
23. Weale AE, Halabi OA, Jones PW, White SH. Perceptions of
outcomes afte unicompartmental and total knee replacements. Clin
Orthop Rel Res. 2001; 382:143-153.
24.SooHoo NF, Sharifi H, Kominski G, Lieberman JR.
Cost-effectiveness analysis of unicompartmental knee
arthroplasty as an alternative to total knee arthroplasty for
unicompartmental osteoarthritis. J Bone Joint Surg Am.2006;
88-A(9):1975-1982.
25.Laskin RS. Unicompartmental knee replacement: some unanswered
questions. Clin Orthop. 2001;392:267-71.
26.Kozinn SC, Scott R. Current concepts review unicondylar knee
arthroplasty. J Bone Joint Surg Am. 1989;71:145-150.
27.Argenson J, Chevrol-benkeddache Y, Aubaniac J. Modern
unicompartmental knee arthroplasty with cement. JBone Joint Surg
Am. 2002;84(12):2235-2239.
28.Naudie D, Guerin J, Parker DA, Bourne RB, Rorabeck CH. Medial
unicompartmental knee arthroplasty with the Miller-Galante
prosthesis. J Bone Joint Surg Am. 2004 Sep;86-A(9):1931-5.
29.Engh GA, Ammeen D. Is an intact anterior cruciate ligament
needed in order to have a well-functioning unicondylar knee
replacement? Clin Orthop Relat Res. 2004;(428):170-3.
30.Koskinen E, Paavolainen P, Eskelinen A, Pulkkinen P, Remes V.
Unicondylar knee replacement for primary osteoarthritis. A
prospective follow-up study of 1,819 patients from the Finnish
Arthroplasty Register. Acta Ortho Scand. 2007;78(1):128-135.
31.Amin AK, Patton JT, Cook RE, Gaston M, Brenkel IJ.
Unicompartmental or total knee arthroplasty? Results from a
matched study. Clin Orthop Rel Res. 2006;451:101-106.
32.Murray DW, Goodfellow JW, O’Connor JJ. The Oxford medial
unicompartmental arthroplasty. A ten-year survival study. J Bone
Joint Surg [Br]. 1998;80-B:983-989.
33.Engh GA, Dwyer KA, Hanes CK. Polyethylene wear of
metal-backed tibial components in total and unicompartmental
knee prostheses. J Bone Joint Surg {Br}. 1992; 74-B:9-17
34.Cartier P, Sanouiller JL, Grelsamer RP. Unicompartmental knee
arthroplasty surgery, 10-year minimum follow-up period. J
Arthroplasty. 1996;11(7):782-788.
35.Johnson S, Jones P, Newman JH. The survivorship and results
of total knee replacements converted from unicompartmental knee
replacements. Knee. 2007;14(2):154-157.
36.Saldanha KAN, Keys GW, Svard UCG, White SH, Rao C. Revision
of Oxford medial unicompartmental knee arthroplasty to total
knee arthroplasty – results of a multicentre study. Knee.
2007;14(4):275-279.
37.Borjesson M, Weidenhielm L, Mattsson E, Olsson E. Gait and
clinical measurements in patients with knee osteoarthritis after
surgery: a prospective 5-year follow-up study. The Knee.
2005;12:121-127.
38.Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee
Society clinical rating system. Clin Orthop Rel Res.
1989;(248):13-14.
39.Dawson J, Fitzpatrick R, Murray D, Carr A. Questionnaire on
the perceptions of patients about total knee replacement. J Bone
Joint Surg [Br]. 1998;80-B:63-69.
40.Kleijn LLA, van Hemert WLW, Meijers WGH, Kester ADM, Lisowski
L, Grimm B, Heyligers IC. Functional improvement after
unicompartmental knee replacement: a follow-up study with a
performance based knee test. Knee Surg Sports Traumatol Arthrosc.
2007;15:1187-1193.
41.Patil S, Colwell CW, Ezzet KA, D’Lima DD. Can normal knee
kinematics be restored with unicompartmental knee replacement? J
Bone Joint Surg. 2005; 87-A(2):332-338.
42.Hassaballa MA, Porteous AJ, Learmonth IA. Functional outcomes
after different types of knee arthoplasty: kneeling ability
versus descending stairs. Med Sci Monit. 2007;13(2):CR77-81.
43.Bradbury N, Borton D, Spoo G, Cross MJ. Participation in
sports after total knee replacement. Am J Sports Med.
1998;26(4):530-535.
44.Kuster MS, Spalinger E, Blanksby BA, Gachter A. Endurance
sports after total knee replacement: a biomechanical
investigation. Med Sci Sports Exerc. 2000; 32(4): 721-724.
45.Kuster MS. Exercise recommendations after total joint
replacement. A review of the current literature and proposal of
scientifically based guidelines. Sports Med. 2002;
32(7):433-445.