Assessment of knee joint range of motion and the level of pain in patients after arthroscopic ACL reconstruction in the selected physiotherapy model

The knee joint is the biggest and most complex joint in a human body. An ability to move and over-come obstacles connected with everyday functioning depends to a large extent on its proper functioning. Also, an ability to use a proper, i.e. economic and safe stereotype of gait which determines general human fitness is related to the functional state of the knee joint [1–5]. Therefore, the effects of its damage resulting from various injuries, including gonarthrosis, belong to the most common disorders in the musculoskeletal system regarding lower limbs. The most profound effects of knee joint injuries include ligament, especially anterior cruciate ligament (ACL) injuries. In the vast majority of cases, a complete ACL tear requires specialist surgical treatment (ACL reconstruction) [6–17].

Most studies published to date regarding a complex treatment of patients with a complete ACL tear present an assessment of therapeutic regimes implemented after the ACL reconstruction. However, there is a scarcity of findings regarding the role of rehabilitation that would prepare patients to the ACL reconstruction although, according to numerous orthopaedists and physiotherapists, several beneficial procedures from the field of physical therapy and kinesitherapy can be performed in this period.

The studies assessing the role of prehabilitation of patients with knee joint dysfunctions (including a complete ACL tear) carried out by Shaarani [38], Swank [39] and Eitzen [40] as well as our previous experiences [22] indicate the necessity to search for evidence to the thesis that physiotherapy in this period is as significant as physiotherapy after the surgery.

Rehabilitation after the surgery is a very important stage of a complex therapy which determines an optimal result of ACL reconstruction [18–24]. The main aim of rehabilitation is to recover a full function of the knee joint and the whole lower limb which was operated on. Achieving this aim constitutes the basis for realising further objectives, i.e. the return of patients to all their social and professional roles and to recreational and sports activity from before the complete ACL tear. Another aim of complex rehabilitation is to prevent secondary injuries and overloads in other parts of the body which compensate for a knee malfunction in a kinematic chain during various forms of activity [24,25]. The aim of the study is to assess the range of motion (ROM) in the knee joint and the level of pain in patients after single-bundle arthroscopic ACL reconstruction in the selected model of rehabilitation.

The study included 72 randomly selected (1^st degree randomisation) individuals with a complete ACL tear who were qualified for its surgical reconstruction. The diagnosis and qualification were based on a full clinical examination carried out by a doctor specialising in orthopaedics and traumatology. The final diagnosis of a complete ACL tear and of the absence of another disease in the knee joint was made on the basis of magnetic resonance examination. The group included 31 women (43.06%) and 41 men (56.94%) whose mean age was 35 (SD±10.1) and median age was 38.5 (minimum 18 years, maximum 60 years). All the patients who were initially qualified for the study were offered presurgical physiotherapy. After voluntary declarations, the patients were randomly divided into two groups (2^nd degree randomisation). The first group included patients who underwent prehabilitation, the second group included patients who did not undergo presurgical physiotherapy. The programme of postsurgical physiotherapy was the same for both groups. All the study participants underwent a single-bundle ACL reconstruction with the use of semitendinosus and gracilis tendon. The study inclusion criteria were as follows: age > 18 years and < 60 years, informed consent of the patient to participate in the study, declaration of participation in the presurgical physiotherapy programme for the research group and the lack of such declaration for the control group. The study exclusion criteria were as follows: age < 18 years and > 60 years, diagnosed counterindications to physiotherapy procedures (for the research group), other significant dysfunctions of the musculoskeletal system, the lack of informed consent of the patient to participate in the study, bad general state of the patient.

The research group included 37 patients aged 18-60 (mean age 37±10.3 years), i.e. 17 men and 20 women. Mean BMI value for these patients was 24. In this group, 17 patients were diagnosed with ACL injury in the right knee, while 20 patients had an injury in the left knee. Implementing prehabilitation in patients from this group was a significant element of the whole rehabilitation procedure, as it aimed at preparing the knee joint and the patient to function in new conditions. All the participants from this group underwent physiotherapy based on recognised rehabilitation schemes that lasted 28-30 days (2-3 times per week) before the reconstruction. In total, 10-12 therapeutic sessions lasting approximately 120 minutes each were carried out. During prehabilitation patients were informed about the procedures of pre- and postsurgical rehabilitation. Also, mutual expectations were discussed and patients were informed that knee rehabilitation means not only the strengthening of lower limb muscles but also working on the function of the whole lower limb as well as performing stabilising exercises and kinematic chain exercises. Presurgical therapy included the reduction of pain, oedema and inflammation, maintaining or improving ROM, mobilisation of the femoropatellar joint, isometric exercises of the quadriceps muscle, maintaining or improving gait patterns and learning to do exercises which will be performed in the first days after the surgery (flexing the knee with the heel moving on the floor, straight leg raise (SLR), mini squats, limb lifting), making the patients aware of the significance of reaching a full extension in the knee joint and practice of walking with crutches. Moreover, such physical therapy regimes as localised cryotherapy, quadriceps electrostimulation and magnetic field according to the table of treatment procedures defined by the producer were performed in the area of the knee joint.

The control group included 35 patients aged 18-60 (mean age 34±10.0 years), i.e. 24 men and 11 women who did not undergo prehabilitation for various reasons. Apart from general recommendations of an orthopaedist and physiotherapist regarding general prophylaxis of the injury, the participants were instructed about special exercises for patients with ACL injury. Mean BMI value in this group was 25. In the control group, 13 patients were diagnosed with ACL injury in the right knee, while 22 patients had the left knee injury.

There were no statistically significant differences between the groups regarding age, gender, BMI and the injury side (tab. 1).

In order to assess the patients, ROM in the knee joint was measured. The examination started with a patient lying in a prone position and the foot of an examined limb positioned behind the edge of the surface on which the patient was lying. The thigh was stabilised. The stationary arm of a goniometer was positioned along the long thigh axis and towards the greater trochanter, while the movable arm was positioned along the shin towards the lateral ankle. The centre of the measuring device was placed at the head of fibula in line with the transverse axis of the joint. A movement of active flexion and extension in the knee joint was performed under the supervision of the physiotherapist [25,34,35]. In order to assess pain in the operated knee joint, Visual Analogue Scale (VAS) was applied. It is a method aimed at subjective assessment of pain intensity. Pain intensity with the use of VAS was assessed by marking a point which reflected pain intensity subjectively defined by the patient on a 10-centimetre line, where 0 meant no pain and 10 reflected the strongest pain imaginable. Expressing pain intensity in numerical values made it possible to draw comparisons both between control examinations in one patient and between different patients. Due to its simplicity and universal application, this method is one of the most widely used tools for measuring pain intensity [27,33].

The statistical analysis methods used in this study are described below. In order to describe numerical variables, standard descriptive statistics, i.e. mean values, standard deviations, medians, quartiles and ranges were applied. While analysing normal distribution variables, Student’s t-test was used, while in the analysis of variables without normal distribution, Mann-Whitney U test and Wilcoxon test were applied. Moreover, the analysis of variance (ANOVA) was performed. Statistical calculations were made with Excel and Statistica 10.0 software. Statistical significance was set at the level of p<0.05. Statistical calculations were made in the Department of Medical Information Technology and Telemedicine of Warsaw Medical University. The study was accepted by the Bioethical Commission of Warsaw Medical University no. KB/35/2013. All the persons qualified for the study gave their informed consent to participate in the study.

Knee joint ROM in both groups was examined three times, i.e. 1 week, 6 weeks and 12 weeks after the ACL reconstruction.

The ranges of flexion in an operated limb examined 1 week after the ACL reconstruction did not differ significantly between the two groups. Mean values defining the level of extension deficit in the knee joint were higher in the control group. The statistical analysis revealed significantly lower extension deficit in the research group (p<0.05). No significant deviations from physiological values of active ROM in the knee joint of a non-operated limb were noted in either of the groups (tab. 2).

In the examination performed 6 weeks after the ACL reconstruction, a significant improvement in the values of active ranges of flexion and extension in the knee joint was noted both in the research and in the control group. However, the results of the statistical analysis in the research group indicated better ranges of active extension in the knee joint of an operated limb which are closer to physiological values (p<0.05). No significant deviations from physiological values of an active movement in the knee joint of a non-operated limb were noted in either of the groups (tab. 3).

The values of active ROM in the operated knee joints obtained in the examination performed 12 weeks after the reconstruction differed slightly from physiological values. In this examination, no statistically significant differences between the groups were noted regarding ROM in the operated knee joints (tab. 4).

In the first examination (after the first week) and in the second examination (after 6 weeks) performed after the ACL reconstruction, no significant differences between the groups regarding a subjective assessment of pain intensity (VAS) in the operated knee joints were noted (p>0.05). In the examination carried out 12 weeks after the reconstruction, lower values of pain intensity in the area of the operated knee joint were noted in the research group. The observed difference in pain intensity between the groups was statistically significant (p<0.05) (tab. 5).

In the work by Smith et al., which is a result of meta-analysis of the studies on the role of rehabilitation in patients with ACL injuries published in recent years, the authors agreed that rehabilitation exerts significant influence on the final effects of the ligament reconstruction. In their conclusions, the authors indicated the necessity to search for a complex, standard rehabilitation programme implemented before and after the ACL reconstruction which would allow for achieving optimally good outcomes for this group of patients [28]. The selected results obtained in a postsurgical period led to a conclusion that implementing physiotherapy prior to the ACL reconstruction is a beneficial procedure in a complex therapy programme [28]. It is also confirmed by several other authors [38–40]. The study by Swank et al. is one of the works in which the authors revealed a significant value of prehabilitation for the treatment of knee joint diseases [39]. The study included 71 individuals qualified for a total knee arthroplasty. The main aim of the observation was to reveal the effects of prehabilitation on an improvement in the strength and function of the knee joint before the arthroplasty. Prehabilitation proved to be an efficient way of regaining muscle strength and improving abilities of performing functional tasks in patients before knee arthroplasty [39]. Another interesting publication regarding the issue of assessing the value of prehabilitation in patients with knee joint dysfunction which has a similar research thesis to our work is the study by Shaarani et al. [38]. In this study, 20 volunteers awaiting ACL reconstruction were randomly divided into two groups. The first group was a control group, while the other group underwent a special 6-week programme of kinesitherapy carried out under the supervision of a physiotherapist in the out-patient conditions. Moreover, patients from this group were instructed on how to perform the exercises in home conditions. The assessment was performed twice, i.e. directly before the reconstruction and 12 weeks after the surgery. A comparative analysis made on the basis of a single-legged hop test and the results of modified Cincinnati scale revealed that a 6-week programme of presurgical exercises applied in the group of patients qualified for ACL reconstruction led to a significant improvement in the knee function compared to the group of patients who did not exercise (p<0.05). These effects were retained until the 12^th week after the surgery [38].

Another significant work which confirmed the value of physiotherapy in the case of ACL injuries is the study by Eitzen et al. [40] carried out on 100 patients. In this group, all the participants experienced a complete ACL tear after a knee injury and underwent a 5-week rehabilitation programme in which a special set of exercises was applied. Knee joint function of the participants was assessed prior to and after the kinesitherapy programme. According to the results, the 5-week programme led to a considerable improvement in knee joint function. Proper rehabilitation may significantly improve knee joint function before the ACL reconstruction or may be the first step towards further nonsurgical procedures [40].

In the present study, postsurgical assessment was performed in the periods which referred to characteristic phases of rehabilitation after ACL reconstruction, i.e. 1 week, 6 weeks and 12 weeks after the surgery.

In the postsurgical assessment, ROM examination was employed. This test is often recommended by the leading researchers in this field since the lack of physiological ROM in the knee joint (especially the lack of physiological extension) constitutes a serious threat to the reconstructed ligament and the joint itself [11,34,35].

According to Quelarda et al., disturbed ROM is the most common complication after the ACL reconstruction. The authors of this study formulated this conclusion on the basis of the results obtained in the observation of 217 patients after the ACL reconstruction. The primary aim of this observation was to determine presurgical factors responsible for a lengthened deficit of ROM after the ACL reconstruction. ROM in the knee joint was assessed with the use of a goniometer once before the ACL reconstruction as well as 6 and 12 weeks after the surgery. Moreover, seven risk factors which may affect final treatment outcomes, i.e. age, gender, presurgical ROM limitation, meniscus damage, bone damage, delayed surgery up to 45 days and rehabilitation, were taken into account. The results revealed that presurgical ROM limitation and typical damage of the lateral condyle of the femur and tibial plateau are the most significant factors hampering rehabilitation after the ACL reconstruction [34].

In another study, Isberg et al. concluded that early work on knee joint extension after ACL reconstruction did not affect excessive knee joint relaxation [35].

In their study, Shelbourne et al. revealed a correlation between loss of knee ROM and osteoarthritic changes observed in X-ray images in the long term after the ACL reconstruction. These results were related to decreased knee joint function subjectively assessed by patients. The authors of this research recommended developing a complete and symmetric ROM through the realisation of the physiotherapy programme before and after the ACL reconstruction. They also concluded that particular attention should be paid to precise ROM examination and to achieving and maintaining full, symmetric ROM in the long term after the reconstruction [36].

In our study, while assessing ROM in the operated knee joint, it was revealed that compared to the control group, patients from the research group achieved a statistically significant (p<0.05) extension improvement 1 and 6 weeks after the ACL reconstruction.

Moreover, in the present study, pain intensity in the operated knee joint was assessed with the use of VAS. In the first measurements, i.e. 1 and 6 weeks after the surgery, a significant decrease (p<0.05) in mean values of pain intensity in an operated knee was noted in both groups. During the last measurement, i.e. 12 weeks after the reconstruction, significantly lower pain intensity was noted in the research group than in the control group (p<0.05). This is a significant observation since pain, as a basic clinical symptom and one of the major obstacles in the proper functioning of the musculoskeletal system, determines the direction of therapy and treatment outcomes. A similar opinion concerning pain intensity in a postsurgical period in patients after the ACL reconstruction was expressed by Yabroudi et al., who revealed high usefulness of controlling postsurgical pain and oedema in a knee join area [33]. While assessing the value of exercises in open and closed kinematic chains after the ACL reconstruction, Ucar et al. also applied the Visual Analogue Scale [37].

The results of our study and of other researchers dealing with an issue of complex treatment of patients after a complete ACL tear indicated the need for treating prehabilitation as one of the factors determining final treatment outcomes in this group of patients. In the observation, two values defining clinical symptoms significant for the course of rehabilitation (extension and pain intensity in the operated knee joint) appeared to be better in the research group. Physiological extension in a joint which was operated on was recovered faster in the group with physiotherapeutic preparation, which is confirmed by the results of the examination carried out 1 and 6 weeks after the surgery. The difference between the groups was statistically significant (p<0.05). The delay of this process, and particularly the absence of complete extension, constitutes a serious threat for the reconstructed ligament and the joint itself. The second symptom whose values determined in our study confirmed its significance for the prehabilitation is pain intensity in the area of an injured knee. In the last measurement, i.e. 12 weeks after the ACL reconstruction, significantly lower pain intensity was noted in the research group compared to the control group (p<0.05).

• A quicker recovery of the range of extension in the operated knee joint and lower intensity of pain in the final measurement noted in the research group may indicate a certain therapeutic value of presurgical physiotherapy.