Identification of the cause(s) for pain after TKR is of paramount importance. This is critical before an effective treatment plan can be employed. In patients with clear mechanical problems or infection after TKR, the treatment is surgical. In these patients with clear causes of the pain after TKR, physical therapy will not permanently change the symptoms. No miracles can be expected. There is, however, a group of patients with more functional problems, with no clear cause of their problems or a low probability of improvement by revision surgery who should be treated nonsurgically. Physical therapy remains a cornerstone for the treatment here. It also represents the primary treatment in most of the patients with problems after TKR for at least two different reasons. Firstly, it is not rare that the physical therapist helps to establish the cause of the problem while performing a detailed functional assessment. Secondly, it is a less invasive treatment modality and includes a variety of different methods such as manual therapy, electrotherapy, cryotherapy and muscle strengthening exercises.

The physical therapist should make a choice of the right interventions with the goal of preventing complications related to “over treatment”. Up to five percent of patients undergoing TKR will develop severe postoperative motion loss that does not respond to the normal standard of care [5, 13]. In most of the cases, early signs are already present during the hospital stay. Range of motion should normally be 0–110° by weeks 6–8 postoperatively. Physical therapists should contact the orthopaedic surgeon if there is no further weekly improvement in range of motion. A “yellow flag” situation is present when knee flexion is less than 90° after 4–6 weeks. Then a more aggressive physical therapy in combination with sufficient pain management is necessary. This is the case when the patient lacks motivation or shows low self-efficacy. In the situation when the patient’s ROM decreases due to swelling and pain, a too aggressive therapy might have been administered. In these cases, physical therapy should be changed from more stressing range-of-motion exercises to more relaxing and calming physical therapy options. Diabetes mellitus and the type of implant are negative predictors for limitation in range of motion after manipulation under anaesthesia MUA [2].

If physical therapy fails to improve knee motion, MUA might be considered. MUA can be performed before or after 30 days after surgery [27]. The entire spectrum of physiotherapy needs to be tried before MUA is considered.

However, the interval between TKR and MUA seems to correlate inversely with the ROM after MUA. Therefore, manipulation should be performed within the first 4–6 weeks after index surgery.

In our opinion, physical therapy in patients with pain and problems after TKR should consist of the following.

Training dosage is critical to achieve an optimal balance between improving knee function and preventing a further increase in pain that subsequently will lead to even further reduced knee function. As a general rule, patients should be informed about the following guidelines in regard to training dosage. “Exercise smart but not hard” should be the guideline to be adopted and followed [30]:

These guidelines need to be tailored to each patient on an individual basis. Never use these guidelines as a “cookbook”; every patient’s recipe needs a different mixture of spices.

Manual lymph drainage therapy (MLD) is helpful to treat postsurgical oedema of the lower leg. The inclusion of MLD as part of the postoperative rehabilitation pathway following TKR has immediate benefits to swelling and knee motion, arguably the two most important factors that affect early recovery. It has a sympathicolytic, analgetic and muscle tonus decreasing effect. MLD should be performed in the early postoperative phase and has been shown to be effective in improving flexion up to 6 weeks after TKR when compared to conventional care [12] (Figs. 39.1 and 39.2).

CPM combined with physical therapy may offer beneficial results compared to physical therapy alone in the short-term rehabilitation following TKR (Fig. 39.3) [25]. Although there is a lack of strong evidence, a prolonged use of CPM slightly improved short-term ROM in patients with limited ROM at the time of discharge after TKR when added to a semi-standard PT program [20]. CPM may be most effective in a subset of patients with very stiff or painful knees. The frequency and duration of ROM exercises should be tailored to the individual tolerance of the patient, keeping in mind that we want to move forward in terms of ROM and reduction of pain [11]. The Cochrane analysis showed that CPM in combination with PT significantly improves active knee flexion and decreases the length of hospital stay and also the risk of post-surgical MUA [15].

Cycling is an excellent activity to help regain muscle strength and knee mobility (Fig. 39.4). The seat height should be adjusted so that at the bottom of the pedal stroke, the patient’s foot barely touches the pedal. Initially, backward pedaling is easier compared to forward pedaling. Forward pedaling should only be started if a comfortable backward cycling motion is achieved. At the beginning, cycling should last no longer than 5–10 min twice a day, which then can be gradually increased to 20–30 min on a daily basis. Patients should start cycling with an adjusted seat height and short crank to allow for repetitive motion without exceeding the pain level VAS pain >5. If tolerated, the patient can progress to cycling with a normal crank setting.