Knee Surgery, Sports Traumatology, Arthroscopy
Over-voluming predicted by pre-operative planning in 24% of total
· Eric Renault
· Jeremy Valluy
· Mo Saarini
Received: 2 February 2018 / Accepted: 30 May 2018
© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2018
Purpose Numerous studies demonstrated that prosthetic overhang and over-sizing cause pain and stiﬀness following total
knee arthroplasty (TKA), but none considered volume changes within the joint capsule. This study was designed to inves-
tigate diﬀerences in volumes of resected bone compared to implanted components in TKA, and to determine the incidence
and factors related to ‘over-voluming’.
Methods Three-dimensional reconstructions were created from 100 magnetic resonance imaging scans taken to design
patient-speciﬁc instruments for TKA. The preoperative simulations were used to calculate the volume ratio (VR) by dividing
volume of planned components by that of planned bone resections. Uni- and multi-variable linear regressions were performed
to determine associations between ‘over-voluming’ (VR > 1.0) and gender, implant size and version (standard versus narrow),
osteophytes, resection levels, external rotation of the femoral component, hip–knee–ankle (HKA) angle, mechanical lateral
distal femoral angle (mLDFA), and mechanical medial proximal tibial angle (mMPTA).
Results The overall implant/bone volume ratio was 0.91 ± 0.11 (range 0.63–1.16) with ‘over-voluming’ observed in 24 knees.
Multi-variable regression conﬁrmed over-voluming to be associated with lower mLDFA (OR 0.66; CI 0.45–0.93; p = 0.026)
and extensive osteophytes (OR 0.14; CI 0.03–0.61; p = 0.014), but not HKA angle (OR 0.98; CI 0.76–1.26; p = n.s.).
Conclusions Over-voluming was observed in 24% of knees, in which the implant volume exceeded the resected volume by
up to 16%. Over-voluming was associated with intra-articular femoral valgus (low mLDFA), but not directly associated with
tibial deformity (mMPTA) or HKA angle. Over-voluming could be associated with prosthetic overhang or excessive tensions
within the joint capsule, and, therefore, contribute to unexplained pain and stiﬀness following TKA.
Level of evidence IV, Retrospective cohort study.
Keywords Total knee arthroplasty · Pain · Stiﬀness · Over-sizing · Overhang · Volume
It is estimated that 20% of patients are dissatisﬁed following
primary total knee arthroplasty (TKA) . While patient
dissatisfaction has been shown to correlate with socio-demo-
graphic, preoperative, surgical, and postoperative factors [8,
10], unexplained pain and stiﬀness remain frequent compli-
cations [16, 17, 20, 26].
Pain and stiﬀness are often associated with prosthetic
overhang or over-sizing [5, 6, 19], which could lead to
soft-tissue impingements [2, 5, 6] and patellofemoral over-
stuﬃng [13, 22]. The mismatch between bone and implant
dimensions could also exacerbate tensions within the cap-
sulo-muscular joint envelope, which plays a proprioceptive
role in knee kinematics, and thereby induce pain or limit
mobility . To avoid such complications, several authors
* Mo Saﬀarini
Department of Orthopaedic Surgery, Croix-Saint-Simon
Teaching Hospital, Paris, France
Department of Research and Development, Corin-Tornier,
ReSurg SA, ch. de la Vuarpilliere 35, 1260 Nyon,