Abstract
Background
Reduced flexion following knee arthroplasty (TKA) may compromise patient’s function and outcome. The timing of manipulation under anaesthesia (MUA) has been controversial. We present our experience in a high volume practice and analyse the impact of timing.
Methods
All TKA patients requiring MUA from February 1996 to June 2015 under the care of a single surgeon were analysed. MUA was offered to patients who had ≤ 75° of flexion post-op, providing that they had 30° more flexion preoperatively. To address the impact of timing from primary surgery to MUA on flexion gain we looked at 3 groups: Group I ≤ 90 days, Group II 91-180 days and Group III > 180 days.
Results
Sixty two out of 7,423 (0.84%) underwent MUA. The MUA patients were significantly younger than the overall TKA cohort 61.2 vs 70.5 years (p = < 0.01). The median duration between arthroplasty and MUA was 3.9 months (IQR 3.4, Range 1.6-72.5 months). Overall flexion gained at 6-12 Weeks and 1 year post MUA showed significant improvements of 20.9° (p = <0.01) and 25° respectively (p = < 0.01). The flexion gain in group I (≤ 90 days) was significantly better than group III ( > 180 days) both at 6 weeks and 1 year following MUA but not better than group II (90-180 days).
Conclusions
MUA is an effective treatment for reduced flexion following TKA and should be the first line of management after failed physiotherapy. It can still have benefit beyond 6 months but the gains become less effective with time.
Keywords: Knee, Arthroplasty, Reduced flexion, Manipulation, Timing
1. Introduction
Total Knee Arthroplasty (TKA) is one of the most effective treatment modalities for patients with advanced osteoarthritis of the knee.1 The primary aims of TKA are relief of pain and restoration of mobility, but achieving adequate flexion is also desirable.2 Despite modern implant designs, contemporary surgical techniques, and physiotherapy, reduced flexion still occurs postoperatively, affecting both function and patient satisfaction.2
Stiffness causing reduced flexion following TKA is a challenging complication for both the surgeon and the patient.3, 4 The incidence has been reported as being between 1.3% and 23%.2, 3, 4, 5, 6, 7 This wide range may be due in part to varied definitions within the literature.2 Kim et al.2 describe it as a flexion contracture of >15° and/or <75° of knee flexion, whereas Christensen et al.8 have defined it as an arc of knee motion <70°. Management of stiffness includes manipulation under anaesthesia (MUA), arthroscopic arthrolysis,9, 10, 11, 12 surgical debridement and revision arthroplasty.2, 10, 12, 13, 14, 15 There are no universally accepted criteria for diagnosis of reduced flexion, nor does consensus exist on appropriate timing of intervention.2, 9
The primary aim of this retrospective review was to determine the impact of the time interval between the date of TKA and MUA with respect to flexion gain. We considered a flexion gain of ≥15° after MUA as being clinically worthwhile and categorized the patients into three groups depending on the timing of the procedure. Furthermore, we analyzed the effect of various factors on the outcome of MUA including, age, gender American Society of Anaesthesiologists (ASA) grading, diabetes, Body Mass Index (BMI), time since primary operation and pre-operative flexion.
2. Patients and methods
This was a retrospective review of prospectively collected data from patients who had an MUA after TKA between 1st of February 1996 and 2nd of June 2015. As this was a service evaluation, ethical approval was not required.
Within our unit, indication for MUA was; ≤75° of flexion following TKA providing that they had at least 30° more flexion preoperatively and failed to improve with physiotherapy. So for example, a patient with 60° of flexion postoperatively would had to have had at least 90° of flexion preoperatively to be eligible. Since 2004 MUA has not be considered before patients are 8 weeks post TKA. Inclusion criteria used were; i. all the patients who fit the unit’s indication for MUA and ii. Patients who had at least one year of follow up. Following MUA, patients were normally reviewed between 6 and12 weeks and at one year to monitor outcome. Data was gathered from theatre records, case notes and our outcomes database (routinely recorded by Arthroplasty Care Practitioners (ACP’s)). Data collection included pre-op ROM, pre-MUA ROM, post-MUA ROM, type of implant used, surgeon grade, timing from TKA to MUA, and various patient-related factors (Table 1). The ROM before and after manipulation and at follow-up were measured using a long-arm goniometer.16 Prior to MUA, patients had a check x-ray to exclude any biomechanical issues such as loosening or malalignment.
Table 1.
Patient Characteristics and Surgical Information.
| Patient Characteristics | Frequency (n = 62) | Percentage (%) |
|---|---|---|
| Gender | ||
| Male | 19 | 30.6% |
| Female | 43 | 69.4% |
| aASA Grade | ||
| 1 | 11 | 17.7% |
| 2 | 42 | 67.7% |
| 3 | 9 | 14.5% |
| Co-Morbidities | ||
| Cardiovascular Disease | 8 | 12.9% |
| Hypertension | 29 | 46.8% |
| Hypercholesterolaemia | 12 | 19.4% |
| Diabetes | 9 | 14.5% |
| Atrial Fibrillation/Palpitations | 9 | 14.5% |
| Asthma | 9 | 14.5% |
| Gastrointestinal Problems | 19 | 30.6% |
| Depression | 5 | 8.1% |
| Other | 32 | 51.6% |
| BMI Category | ||
| Normal (18.5–24.9) | 8 | 12.9% |
| Overweight (25–29.9) | 18 | 29.0% |
| Obese Class I (30–34.9) | 28 | 45.2% |
| Obese Class II (35–39.9) | 7 | 11.3% |
| Obese Class III (≥ 40) | 1 | 1.6% |
| Side of Operation | ||
| Right | 31 | 50.0% |
| Left | 31 | 50.0% |
| Pre-op Deformity | ||
| Valgus | 16 | 25.8% |
| Varus | 33 | 53.2% |
| Valgus and bPF | 2 | 3.2% |
| Varus and bPF | 6 | 9.7% |
| Neutral | 5 | 8.1% |
| Sperner Grade | ||
| 1 | 27 | 43.5% |
| 2 | 21 | 33.9% |
| 3 | 11 | 17.7% |
| 4 | 3 | 4.8% |
| Primary Implants | ||
| LCS Cemented Knee | 5 | 8.1% |
| LCS Cementless Knee | 54 | 87.1% |
| ROCC Cementless Knee | 3 | 4.8% |
| Primary to MUA | ||
| ≤ 90 days | 13 | 21.0% |
| 91–180 days | 31 | 50.0% |
| > 180 days | 18 | 29.0% |
ASA–American Society of Anaesthesiologist’s Physical status.
PF – Patellofemoral Arthritis.
2.1. Technique of MUA
A general anaesthesic (GA) with peripheral nerve blocks (femoral and sciatic) was used until 2012 thereafter GA was replaced by spinal anesthesia and blocks. We feel that spinal anaesthesia with minimal sedation allows the patient to be aware of their knee being flexed and thus helps reinforce the success of the procedure. The risk of possible fracture was explained to all patients as well as the possibility that the MUA may not be effective and could on occasion result in less flexion. Initially, under adequate muscle relaxation, ROM was accurately recorded prior to MUA. MUA was then performed with the ipsilateral hip flexed to 90° and the leg held by the foot and calf. A steady progressive bending moment was applied to the knee until a palpable and audible break of adhesions was achieved. Firm pressure was then continued until no further movement could be obtained. This can take several minutes of steady pressure. No attempt was made to correct fixed flexion. ROM was then recorded again with two measurements for flexion – one passive and then forced. The senior author (DB) performed all MUAs.
The patient’s knee was then kept flexed until the Continuous Passive Motion (CPM) machine was put in position by the physiotherapist in the recovery ward. The CPM machine was set immediately to the maximum ROM that had been achieved. The CPM remained in place until late the first night and was then reapplied early the following morning with the same being repeated on Day two. The patient was mobilised with care and assistance because of the nerve blocks on Day one. Patients were normally discharged on the afternoon of Day two. All patients had outpatient physiotherapy to try and maintain the increased flexion achieved after MUA.
2.2. Statistical analysis
To address the main aim of this review, patients were divided into three groups based on the time interval between TKA and MUA. Group I ≤ 90 days, Group II 91–180 days and Group III > 180 days. Data was analysed using SPSS (IBM SPSS Statistics for Windows, Version 22.0, Armonk, USA). All appropriate data was assessed for normality of distribution and parametric/non-parametric testing applied. Baseline patient demographics, ASA grade and ROM measurements were compared across groups to assess for significant differences between groups.
Our primary outcome – flexion gain post MUA, was used as a continuous variable. Analysis of variance (ANOVA) using Kruskal Wallis Tests was carried out with post-hoc analysis (Wilcoxon Signed Rank Tests) to test for significant differences between groups and where these differences specifically lay. Bonferonni adjustment of the alpha value was made for this post-hoc analysis, giving a modified value of p = ≤0.02. We also analysed flexion gain of ≥15° as a categorical variable between groups. Categorical data was analysed using Chi-Square analysis. With the exception of the adjusted alpha value, significance was set at the level of p = ≤0.05.
3. Results
A total of 7423 primary TKAs were performed within our unit between 1st Feb 1996 and the 2nd of June 2015 under the care of the senior author (DB). From this population, 62 patients (0.84%) subsequently underwent an MUA, including one patient who had MUA on consecutive knees done over 4 years apart and one patient who had two MUAs on the same knee 9 months apart.
The mean age of patients at the time of their primary surgery was 61.0 years (±8.6, Range 38–78 years) which was significantly (p = < 0.01) younger than 70.5 years for our general TKA population. In line with the TKA population, the MUA group included more females than males (2:1 ratio) with 43 (69.4%) being female. The MUA group had a significantly lower BMI (p = 0.002; 29.8 vs 32.0) and a higher incidence of diabetes (14.5% vs. 10.2%); p = 0.005). Patient characteristics, baseline and surgical information are provided in Table 1.
The majority of patients (95.2%) had an LCS (Depuy-Synthes, Warsaw) knee implant (Table 1). Fifty-three manipulations (85.4%) were within 12 months of the primary procedure. The median time between arthroplasty and MUA was 3.9 months (IQR 3.4, Range 1.6–72.5). Only three patients had their MUA within 8 weeks of their TKA with the shortest interval being 7 weeks. Since November 2004 all MUAs have taken place beyond 12 weeks. The median length of stay for MUA was 2 days (IQR 1, Range 1–10 days).
Overall, median flexion improved from 60.0° (IQR 20, range, 20°–75°) pre-MUA to 83.0° (IQR 16, range, 40–110°) post-MUA at 6–12 weeks and 84.5° (IQR 25, range 45°–123°) at one year (Fig. 1). Wilcoxon Signed Ranks Tests were performed on median improvements in terms of flexion gained at 6–12 weeks and 1 year post MUA which showed significant improvements of 20.0° (p = <0.01) and 23.5° respectively (p = <0.01). There was no significant difference overall (p = 0.97) in flexion gained between 6 and 12 weeks and 1 year post MUA. Fifty-four (87.1%) patients had a fixed flexion deformity (FFD), median 10° (IQR 10, Range 5–30) prior to MUA. In 21 patients (33.8%) the FFD was ≥15°. Although no attempt was made to correct the FFD at the time of MUA by the 6–12 week timeframe, 15 (24.2%) patients had full extension while 25 (40.3%) had full extension at 1 year. At one year, 56 (90.3%) patients had an improvement in flexion, while 2 (3.2%) patients stayed the same and 4 (6.5%) worsened by 18°, 15°, 5° and 4°.
Fig. 1.
Graph showing the median flexion at pre-op, 6–12 weeks and at one year, in the three groups.
Patients were categorised into three groups depending on the timing of their MUA from their index operation (Group I ≤ 90days, Group II 91–180 days and Group III > 180 days). There were no significant baseline differences between groups in relation to age at date of primary operation, age at date of MUA, gender, BMI, ASA grade, pre-op flexion or in terms of median fixed flexion. Table 2 details flexion gain for each group showing significant differences at both 6–12 weeks and 1 year post MUA. Post-hoc analysis showed that the significant differences lie between Groups I and III, at 6 weeks (30.0° vs 15.0°; p = 0.008) and at one year (40.0 vs 11.5; p = 0.01). There were also differences between groups I and II at one year, however, with the alpha adjustment (p = ≤0.02) for multiple comparisons, these were not significant (p = 0.03). Since the end of 2004 only 2 MUAs have been performed at <90 days one at 86 and the other at 88 days. At one year, more patients in Group I had achieved a flexion gain ≥ 15° than Group III (92.3% vs 44.4%; p = 0.02) (Table 3/Fig. 1).
Table 2.
Flexion Gain by Time from Primary Operation to MUA.
| Follow-up | Flexion Gain by Timeframe Median (IQR) |
|||
|---|---|---|---|---|
| ≤90 Days | 91–180 Days | >180 Days | p | |
| 6–12 Weeks | 30.0° (23.0) | 20.5° (21.0) | 15.0° (14.0) | 0.02* |
| 1 Year | 40.0 (24.0) | 22.0 (15.0) | 11.5 (16.0) | 0.001* |
*p = ≤0.05.
Table 3.
Flexion gain ≥15° at 6–12 Weeks and 1 Year by Time to MUA.
| Flexion Gain ≥ 15° | Time to MUA–Grouped |
p | ||
|---|---|---|---|---|
| ≤90 Days | 91–180 Days | >180 Days | ||
| 6–12 Weeks | 12 (92.3%) | 23 (76.7%) | 11 (64.7%) | 0.21 |
| 1 Year | 12 (92.3%) | 24 (77.4%) | 8 (44.4%) | 0.008* |
*p = ≤0.05.
None of the patients had further surgery but there were three patients who had complications all of which resolved with conservative management. One patient had readmission post MUA for pain management, another had a haemarthrosis following MUA and a third patient suffered a cerebrovascular accident (CVA) on day 2 post MUA from which they made a full recovery. One patient who initially improved after the first MUA but later developed reduced flexion with no obvious underlying cause detected. She had a second MUA nine months later with more lasting benefit, with a flexion of 90°at one year review following the second MUA.
4. Discussion
Our cohort included 62 MUAs carried out over a 17 year period. The incidence of MUA following TKA varies widely between 1.3% and 23%.2, 3, 4, 5, 6, 7 In comparison, the MUA incidence in our unit of 0.83% is, to our knowledge, the lowest currently cited in the literature. Laubenthal et al.17 showed that patients require 67° of knee flexion during the swing phase of gait, 83° to ascend stairs and between 90° and 100° of flexion are required to descend stairs. To stand up from a normal sized chair, people require knee flexion range of approximately 93°.17 The aim after TKA is therefore to achieve flexion of about 90°–100° thus minimising the potential of functional problems in the patient’s daily life.
Although preoperative ROM is the most important influencing factor for postoperative ROM,10 the aetiology for reduced flexion following TKA is poorly understood and is often described as being multifactorial. Several factors such as patient-related factors, surgical technique errors, and postoperative complications should be considered.3, 18, 19, 20, 21 Inflammatory arthritis such as juvenile rheumatoid arthritis and ankylosing spondylitis seem to play a role in the development of postoperative flexion loss.3 Some studies have shown that patients with higher BMIs had a greater incidence of MUA and a lower preoperative and postoperative ROM22 while others have shown no association.23 Interestingly, in our series the BMI was significantly lower (29.8 vs 32.0, p = 0.01). Age also seems to play a controversial role with some authors reporting a higher incidence of postoperative stiffness in younger patients undergoing TKA.4, 5 Our series supports this finding with our MUA patients being significantly younger (61 vs 70.5; p = ≤0.01) than our standard TKA population There is a reported correlation with diabetes and reduced flexion,23, 24 and again our study supports this with a higher incidence of diabetes in the MUA population (14.5% vs. 10.2%); p = 0.005. Reflex sympathetic dystrophy characterized by knee pain and stiffness can be present in 0.8% of patient undergoing TKA.25 We had none in our cohort.
Various surgical techniques have been described for the treatment of reduced flexion after TKA with variable results. Arthroscopy (with or without MUA) results in similar gains in ROM in patients with arthrofibrosis after TKA.10 Open arthrolysis to treat arthrofibrosis after TKA seems to have inferior results when compared with MUA or arthroscopy.10 Arthrolysis and exchange of the tibial insert generally has had poor outcomes.13 Arthroscopic release of the posterior cruciate ligament for the treatment of stiffness is shown to be of value if the retained posterior cruciate ligament is tight.26 Revision arthroplasty for the treatment of stiffness has had satisfactory outcomes, although an optimal range of motion has not been attained.8, 12, 13, 26
Significant confusion in the literature is caused by the fact that final increase in knee arc of motion was reported in flexion in some studies and ROM in others. Four studies reported motion in terms of knee flexion,5, 7, 27 whereas three studies reported motion as increase in ROM.12, 15, 28 The reported mean increase in flexion is between 5° and 58.4°.5, 10, 29, 30 The average flexion gain in our patients at 1 year was 23.5° [IQR 30, range;18–63]. The indications for the MUA also vary widely in literature, from <75° flexion at 10 days post op period to <95° flexion at the three month period.10, 15 The protocol in our unit is that any patient with ≤75° flexion following a knee replacement is offered an MUA providing their preoperative flexion range was at least 30° more than their postoperative range. With regard to timing our present practice would be to wait for a minimum of 3 months. Since November 2004 only 2 of our 40 MUAs have been done before 90 days but at 86 and 88 days both were beyond 12 weeks.
Several articles support early manipulation6, 14, 15 while other studies support later manipulation.5, 12, 27, 31 However, the exact timing is unclear. Yercan et al.15 state that patients who had manipulation less than 3 weeks from the index procedure had better final ROM than patients who had manipulation after 3 months from the index procedure. Daluga et al. & Issa et al.4, 23 support using MUA less than 3 months from the index procedure. Esler et al.28, 29 suggest MUA helps motion more when performed before 4 months but reported patients also had noteworthy gains in knee flexion after 4 months. Scranton et al.12 found that the group of patients who had manipulation before 12 weeks had a similar average gain in ROM as patients who had manipulation after 12 weeks (36° vs. 35°). However, in the early group, only one of 12 patients underwent revision surgery, whereas in the late group three of seven patients had revision surgery. Keating et al.5 reported no major difference in final knee flexion before or after 3 months. The general body of current literature suggests that MUA to increase flexion after TKA appears to give better results when performed less than 3 months from the index procedure which is contrary to our practice.
In our experience the median time from knee arthroplasty to manipulation was 3.9 months. In our series there was a statistically significant difference in the flexion gain in patients who had an early MUA (≤90 days) compared to >180 days but not between ≤90 and 90–180 days. Therefore based on our experience we would suggest that MUA is more effective during the first six months. It is also clear that if the threshold for MUA was set at 75° at 3 and 6 weeks many patients would have an unnecessary MUA. Therefore, inevitably any studies which performed MUAs earlier will have a better average increase in flexion as it will include patients who would improve spontaneously. Anecdotally, we had one patient who had a preoperative ROM of 0–130° with 25–70° at 12 weeks. The patient refused MUA and at one year the ROM was 5–120°. It would be interesting to know whether physiotherapy alone, would improve flexion. However, a literature search did not reveal any such case-control studies. It is interesting to note that many of our MUA patients had a spontaneous improvement in fixed flexion post MUA even though this was not addressed at the time of MUA.
The immediate results from MUA in our group were satisfactory. Fifty six patients (90.3%) had improved flexion but six patients (10%) did not benefit from MUA of which two patients (3.5%) had no change and in four patients (6.5%) the flexion was worse by an average of 10.5°. The reported complications from MUA in the literature are fracture, wound dehiscence, patellar ligament avulsions, haemarthrosis, heterotopic bone formation and pulmonary embolism.5, 10 We had three patients with complications all of which resolved with conservative management. None of the patients had further surgery.
There are a number of limitations to this review. It was retrospective, and patients were only followed until one year postoperatively however, the literature suggests that any gains from MUA are maintained in the longterm.5, 27, 31, 32 In addition, we have no control cohort for comparison over time. Nevertheless, the authors believe that the results are valuable because there is paucity in the literature on studies of MUA stratified by the timing of the procedure to improve reduced flexion following TKA.
5. Conclusions
Reduced flexion following TKA can be a devastating complication. MUA can offer a safe and effective solution albeit of limited benefit. We recommend MUA as the first line of treatment after failed physiotherapy for reduced flexion following TKA. Its appears to be more effective if performed within 6 months but MUA can still be beneficial after 6 months. Studies reporting results from early MUA within 6 weeks of TKA will always be better due to inclusion of patients whose flexion would improve spontaneously.
Funding source
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflicts of interest statement
Each author certifies that he or she has no commercial associations (e.g., consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article.
Acknowledgement
The authors would like to thank the outcomes team in Musgrave Park Hospital for help in collecting the data used in the paper.
References
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