Volume 6, Issue 4 (11-2019)                   J. Res. Orthop. Sci. 2019, 6(4): 1-6 | Back to browse issues page

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Shahpari O, Bagherifard A, Jabalameli M, Rahbar M, Hajitaghi H. Preoperative Clinical Correctability and Prediction of the Prosthesis Type in Total Knee Arthroplasty for ‌Severe Osteoarthritic Varus Deformity. J. Res. Orthop. Sci. 2019; 6 (4) :1-6
URL: http://jros.iums.ac.ir/article-1-2058-en.html
1- Bone and Joint Reconstruction Research Center, Shafa Orthopedic Hospital, Iran University of Medical Sciences, Tehran, Iran.
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1. Introduction
Osteoarthritis (OA) is one of the leading causes of pain and disability among elderly individuals [1]. The prevalence of knee OA has been reported by 19.34% in rural areas of Iran in 2014 [2]. As the number of patients over 60 years is estimated to double by 2050, OA is expected to turn into the greatest cause of disability in the general population by 2030 [3, 4].
Total knee arthroplasty (TKA) is considered a successful procedure for symptomatic OA, and its number is also expected to increase parallel to the population aging [5]. Nevertheless, up to 30% of patients are not satisfied with the outcome of TKA [6]. Therefore, improvement of the quality of life of the patients by optimizing TKA results is a healthcare necessity.
A successful TKA aims at achieving optimum alignment, appropriate balance, and deformity correction. In primary TKA, these goals can be attained efficiently by posterior stabilized (PS) TKA. However, certain circumstances are extremely difficult to balance and require constrained prostheses even in primary TKA. In such situations, a constrained condylar knee (CCK) design is the prosthesis of choice [7].
Recent investigations reveal that using CCK prosthesis in primary TKA would not be detrimental to the patient and provides similar outcomes compared with PS prosthesis [7, 8]. Even so, it is generally avoided because of its higher cost, the complexity of the procedure, and greater bone removal [9]. Therefore, the implications of CCK prosthesis should be restricted to the patients who have indications.
Preoperative planning is of critical importance in primary TKA and gives the surgeon an insight to anticipate the potential difficulties, as well as to minimize the risk of premature implant failure [10]. The preoperative identification of prosthesis type is also essential as it ensures the availability of appropriate prosthesis and addresses the patients’ expectations through accurate preoperative counseling.
To date, prosthesis type is mainly determined based on the intraoperative information. We hypothesized that the preoperative characteristics of the patients, such as clinical correctability, could be used in the preoperative determination of prosthesis type. In this study, in a series of patients with severe osteoarthritic genu varum deformity, we aim at investigating factors that could help in the identification of patients who might require a CCK prosthesis.
2. Methods
This retrospective study was approved by the institutional review board of our institute, and written informed consent was obtained from patients to use their medical data. In a retrospective study, patients who underwent primary TKA between 2017 and 2019 for severe osteoarthritic genu varum deformity (varus angle ≥20º) were evaluated for the eligibility criteria (Figure 1). Patients with the diaphyseal femoral or tibial canal owing to prior trauma, operation, or retained hardware, were excluded. Patients with incomplete medical records were excluded, as well.
A total of 30 patients were eligible to include in the study. All the patients had tibia vara. No patient had recurvatum. All operations were performed under general anesthesia, using a standard medial parapatellar approach. A tourniquet was inflated at the beginning of the procedure and kept inflated until the wound closure. The decision to use a CCK prosthesis was mainly based on the preoperative level of ligamentous stability, intraoperative evaluation of competency of the collateral ligaments, and on-table evaluation of coronal plane stability following the soft-tissue release. In both groups, Zimmer NexGen® Legacy® knee prosthesis was implanted in the majority of cases.
The demographic data were extracted from the patients’ medical records. The correctability of the deformity was determined before the operation, and categorized as correctable and non-correctable. In this respect, the knee would be considered correctable if it could clinically approximate the knee alignment to the normal alignment, using a valgus force.
Intraoperative information included the data regarding the performance of reduction osteotomy, soft-tissue release, and the pie-crust technique. Soft-tissue release was performed sequentially and the following steps: step 1. osteophyte removal and release of the deep medial collateral ligament; step 2. posterior oblique ligament, and semimembranosus release; step 3. superficial medial collateral ligament release; and step 4. pes anserinus tendon release [11].
Statistical analysis
SPSS V. 16 was used to analyzing the obtained data. The descriptive data were provided as number and percentage of mean±SD. The association between the choice of prosthesis and pre- or intra-operative parameters was analyzed using the Chi-square test. A comparison of means between the two study groups was made using the Mann-Whitney U test. The P<0.05 was considered as significance level.
3. Results
A total of 30 patients with a mean±SD age of 64.6±8.7 years were included in this study. The study population consisted of 4 (13.3%) males and 26 (86.7%) females. Lateral laxity was present in 7 (23.3%) patients. A CCK prosthesis was used in 11 (36.7%) cases. Fourteen (46.7%) deformities were preoperatively correctable. The release was performed at step 1 in 3 (10%) patients, at step 2 in 19 (63.3%), and at step 3 in 8 (26.7%) patients. No step 4 release was performed in this series. Reduction osteotomy was performed in 18 (60%) patients. Pie-crusting was done in 10 (33.3%) patients. Table 1 presents the demographic, preoperative, and intraoperative characteristics of the patients.
Age and sex of the patients were not statistically associated with the type of prosthesis (P=0.52 and P=0.73, respectively). The presence or absence of preoperative lateral laxity was not related to the kind of prosthesis, as well (P=0.48). A significant association was found between the preoperative correctability of deformities and the type of prosthesis; all CCK prostheses were used in patients who were preoperatively non-correctable (P<0.001). Also, the step of release was significantly associated with the type of prosthesis so that CCK prosthesis was used in all patients with step 3 release and no patients with step 1 release (P<0.001). Reduction osteotomy and pie-crusting were not associated with the type of prosthesis (P=0.53 and P=0.17, respectively). Table 2 presents the comparison of the demographic, preoperative, and intraoperative characteristics of the patients.
Preoperative correctability was significantly associated with the step of release; all deformities with step 3 release were preoperatively non-correctable (P=0.008). No significant association was found between the preoperative correctability and other intraoperative characteristics, as well as demographic features.
4. Discussion
Several surgical treatments have been developed for the treatment of osteoarthritic genu varum deformity ranging from attempted osteotomy techniques to TKA [12, 13]. Severe osteoarthritic genu varum deformities are generally managed with TKA. However, optimizing ligamentous balance and maximizing the range of motion is challenging in these patients and many patients will require a CCK prosthesis. The identification of patients who may need a CCK prosthesis could help the optimal preoperative planning of TKA, which is of paramount importance [10, 14].
In this study, we aimed at investigating factors that could be used in the identification of patients who might require a CCK prosthesis. Based on the results of the present study, the preoperative correctability of the deformity could be used as a critical factor in the prediction of the patients who might require a CCK prosthesis. 
A significant association was also found between the preoperative correctability and the step of release so that a higher step of release was required in non-correctable deformities. The step of release was also significantly associated with the type of prosthesis. Thus, non-correctability results in the higher stages of release and more implication of CCK prosthesis.
Puah et al. compared the clinical and functional outcomes of CCK and PS in 38 paired patients who underwent TKA. There was no significant difference in 6-month knee extension, knee flexion, Oxford Knee Score, and 36-item short form survey total hip arthroplasty scores of the two study groups. There was no significant difference in 2-year knee extension, knee flexion, Oxford Knee Score, and SF-36 scores of the two study groups, as well. They concluded that using CCK in primary THA provides similar clinical and functional outcomes as those of PS prostheses, despite increased constraint [9]. The study of Rai et al. revealed the same results. However, they mentioned that using CCK has its complications [7]. Besides, CCK is associated with high cost, complexity, and bone removal. This evidence supports the importance of preoperative identification of patients who might need a CCK prosthesis in TKA.
Baldini et al. reviewed patients’ or deformity-associated factors that can make TKA a challenging procedure. These factors include several previous operations and incisions, severe coronal deformities, a stiff knee, genu recurvatum, extra-articular deformities such as tibia vara, previous osteotomy around the knee, and chronic dislocation of the patella [15]. The present study revealed that the preoperative non-correctability of the deformity could group the factors, as pointed out in the study of Baldini et al.
Goltzer et al. aimed at determining if preoperative radiographic criteria of valgus knees can help to predict the extent of required soft tissue release, as well as the level of constraint needed to balance the knee. A total of 807 consecutive TKA standing hip-knee-ankle radiographs were analyzed in this study. Their analyses revealed that preoperative radiographic characteristics of the valgus knee could be implicated in predicting the extent of the lateral soft-tissue release and the necessity of constrained articulation in TKA. They suggested that this information could be useful to offer accurate preoperative counseling to patients and to ensure the availability of appropriate prosthesis during the operation [16]. 
The results of the present study revealed that preoperative clinical correctability could also be used as a factor to predict the amount of soft-tissue release, as well as the necessity of constrained articulation.
Some surgeons consider factors such as older age and gender in their decision-making to use a constrained articulation [16]. The results of the present study revealed no association between the demographic factors of the patients and the choice of prosthesis.
This study has some limitations. The main limitation of the study was the retrospective nature of the survey, as well as the small number of samples. Besides, the level of correctability was not determined quantitatively. We believe that the quantitative evaluation of preoperative correctability will result in the further codification of patients, who might require a CCK prosthesis. Therefore, we suggest further prospective investigations with larger sample sizes and quantitative evaluation of preoperative clinical correctability.
5. Conclusion
The preoperative clinical evaluation of correctability could be used in the identification of patients who may need a CCK prosthesis. This information could be used to facilitate surgical planning and efficiency by ensuring that appropriate prosthesis options are available when required. Furthermore, it may facilitate preoperative patients’ counseling to address their expectations more accurately.
Ethical Considerations
Compliance with ethical guidelines
Written informed consent was obtained from patients to use their medical data.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Authors' contributions
Conceptualization: Abolfazl Bagherifard; Study supervision: Mahmoud Jabalameli; Critical revision of the manuscript: Mohammad Rahbar; Data collection: Omid Shahpari; Interpretation of results and drafting the manuscript: Hossein Hajitaghi.
Conflict of interest
The authors declared no conflict of interests.

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Type of Study: Research Article | Subject: Knee surgery
Received: 2019/08/10 | Accepted: 2019/10/5 | Published: 2019/12/25

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