A prospective study of day of surgery discharge in 368 consecutive patients with unicompartmental knee replacement.

INTRODUCTION: There has been an increased focus on fast-track (FT) programmes and the potential to convert unicompartmental knee replacement (UKR) from short-term admission to outpatient surgery. However, relatively few studies have been presented and with differences in selection criteria and completion rates. The purpose of this study was to describe patient selection and completion rates in a patient group undergoing UKR in two high-volume FT knee surgery clinics. METHODS: All consecutive patients (n = 368) referred to and selected for UKR were screened for eligibility for outpatient surgery with discharge on the day of surgery (DOS). Reasons why the patients were not discharged were recorded in patients not completing the outpatient pathway, and readmissions and complications were recorded until three months post-operatively. RESULTS: Among all referred and screened patients, 69% were considered eligible for outpatient surgery. DOS discharge occurred in 59% of the operated patients and in 37% of all referred and screened patients. Main reasons for why patients were not discharged were active wound drainage and lack of mobilisation due to pain, nausea and vomiting. Two patients were readmitted during the first 24 hours due to wound drainage. One patient had a lung embolus and one patient an acute myocardial infarction during the follow-up period. CONCLUSIONS: This study illustrates that not all patients in a consecutive patient group for UKR were feasible for outpatient surgery. Further studies should focus on optimising pain treatment and reducing post-operative nausea. FUNDING: none. TRIAL REGISTRATION: not relevant.

Equal tibial component fixation of a mobile-bearing and fixed-bearing medial unicompartmental knee arthroplasty: a randomized controlled RSA study with 2-year follow-up.

Background and purpose - Differences in stress distribution in a mobile-bearing and fixed-bearing unicompartmental knee arthroplasty (UKA) design might lead to a difference in fixation of the tibial component. We compared tibial component migration of a mobile-bearing (MB) UKA and a fixed-bearing (FB) UKA using radiostereometric analysis.Patients and methods - In a randomized, patient-blinded clinical trial 62 patients received either the MB Oxford UKA or the FB Sigma UKA. The patients were followed for 24 months with radiostereometric analysis. Clinical outcome was assessed with Oxford Knee Score (OKS), RAND-36 and leg extension power.Results - Migration of the tibial components was similar between groups throughout follow-up. At 12 months, MTPM of the tibial component was 0.44 mm (95% CI 0.34-0.55) for the MB group and 0.40 mm (CI 0.31-0.50) for the FB group. Between 12 and 24 months, the tibial components migrated with a median MTPM increase of 0.03 mm (CI -0.02 to 0.08) in the MB group and 0.03 mm (CI -0.02 to 0.07) in the FB group. Continuous migration of the tibial component was found for 1 MB UKA and 2 FB UKAs. Both groups showed similar and clinically relevant improvement in clinical outcome.Interpretation - MB and FB tibial components had similar good fixation and clinical improvement until 2 years. Based on this study, a low 5- to 10-year revision rate can be expected for both implants.

The lateral joint space width can be measured reliably with Telos valgus stress radiography in medial knee osteoarthritis.

OBJECTIVE: To examine the reproducibility of valgus stress radiographs with the Telos stress device for assessment of lateral compartment degenerative changes in patients with medial osteoarthritis of the knee. MATERIALS AND METHODS: A prospective reliability study was performed. Seventy-nine patients (80 knees) were included, and standardized valgus stress radiographs were obtained using the Telos stress device. Osteophytes and joint space narrowing (JSN) were graded using the OARSI (Osteoarthritis Research Society International) classification, and the joint space width (JSW) was measured in millimeters. Reproducibility was determined as intra-and inter-rater reliability and test-retest reliability. Weighted kappa was used to determine the reliability of osteophyte and JSN grading, and the intra-class correlation coefficient for JSW. RESULTS: Grading of osteophytes had an intra- and inter-rater reliability ranging from 0.40 to 0.83 on the medial side and ranging from 0.39 to 0.87 on the lateral side. Grading of medial JSN had an intra- and inter-rater reliability ranging from 0.62 to 0.84, and grading of lateral JSN had an intra- and inter-rater reliability ranging from 0.32 to 0.65. Intra- and inter-rater reliability of JSW ranged from 0.84 to 0.98 on the medial side, and from 0.59 to 0.89 on the lateral side. Test-retest reliability of JSW of the medial and lateral side ranged from 0.69 to 0.92. CONCLUSIONS: Standardized valgus stress radiographs taken with the Telos stress device are a reliable supplement in the assessment of medial OA of the knee. Evaluation of the lateral compartment on valgus stress radiographs is most reliable with measurement of the lateral JSW.

Low implant migration of the SIGMA® medial unicompartmental knee arthroplasty.

PURPOSE: The purpose of this study was to evaluate implant migration of the fixed-bearing Sigma® medial unicompartmental knee arthroplasty (UKA). UKA is a regularly used treatment for patients with medial osteoarthritis (OA) of the knee. UKA has a higher revision rate than total knee arthroplasty. Implant migration can be used as a predictor of implant loosening. METHODS: A prospective radiostereometric cohort study was performed. Forty-five patients with medial OA of the knee were included and received a cemented Sigma® UKA. The patients were followed for 24 months with radiostereometric analysis (RSA) and clinical outcome scores (Oxford knee score). Clinical precision was based on double determinations taken at 4 and 12 months. Tibial implants were classified as stable (difference in MTPM < 0.2 mm between 1 2 and 24 months) or as continuously migrating (difference in MTPM > 0.2 mm between 12 and 24 months). RESULTS: No significant differences in migration were found for the femoral component. For the tibial component, a difference of 0.05 mm was shown for translation on the x-axis between 4 months and 12 (p < 0.01) and between 4 months and 24 months (p < 0.01). A difference of - 0.23 to - 0.50° was shown for rotation around the x-axis (p < 0.01) and a difference of - 0.11° was shown for rotation around the z-axis between 4 and 12 months (p = 0.02). These differences in migration over time were small and fall within the clinical precision of the measurements. Tibial components were divided into a stable group (N = 26) and a continuously migrating group (N = 11), which showed a significant difference in maximal total point motion (MTPM) (p < 0.01). The Oxford knee score improved significantly from poor before surgery (23.2) to good at follow-up (37.5-40.9). CONCLUSIONS: The Sigma® UKA showed low implant migration and good clinical outcomes, suggesting that the Sigma UKA can be used in clinical practice. However, continuous migration was found in 30% of our patients which could indicate a risk of later revision surgery in this group. LEVEL OF EVIDENCE: II.

Methylprednisolone reduces pain and decreases knee swelling in the first 24 h after fast-track unicompartmental knee arthroplasty.

PURPOSE: Unicompartmental knee arthroplasty (UKA) results in less operative trauma and faster patient recovery than after a conventional total knee arthroplasty. Despite an increased focus on multimodal analgesic strategies, there is still a substantial level of patient-reported pain in the early postsurgical period after UKA. The purpose of the study was to evaluate the effect of a single preoperative dose of systemic methylprednisolone on postsurgical pain after fast-track UKA. METHODS: Seventy-two patients in two consecutive series undergoing unilateral UKA were included in a prospective cohort study. The patients (n = 35) in the treatment group received a single preoperative dose of systemic methylprednisolone 125 mg, whereas the control group (n = 37) did not. Outcome measures were postsurgical pain at rest and during walking, consumption of opioids for pain rescue, knee swelling and knee range of motion, and complications. RESULTS: In the first 24 h after surgery, the treatment group had less pain at rest (p < 0.001) and during walking (p < 0.001) and less consumption of opioids (p = 0.01) in comparison with the control group. Furthermore, the treatment group had 2.2 cm less knee swelling (p = 0.02) in the first post-operative day, and better knee extension (p = 0.004), whereas knee flexion was similar (n.s.) between groups. No serious complications were associated with the treatment. CONCLUSION: Addition of a single preoperative dose of 125 mg systemic methylprednisolone to a multimodal analgesic regime significantly reduced postsurgical pain and opioid consumption and decreased knee swelling in the first 24 h after fast-track UKA. LEVEL OF EVIDENCE: Therapeutic study, Level II.

Effect of compression therapy on knee swelling and pain after total knee arthroplasty.

PURPOSE: Knee swelling after total knee arthroplasty may impair postoperative mobilisation and training, and as medical elastic compression stockings are well tolerated and effective to prevent oedema, haematoma and postoperative pain after venous surgery, we wanted to study whether this effect could be transferred to total knee arthroplasty surgery reducing postoperative swelling and pain and thereby facilitating mobilisation and improving patient-reported knee function. METHODS: In a randomised controlled study, 88 patients were randomised to use either a medical elastic compression stocking or no stocking from the first postoperative day and the following 4 weeks after total knee arthroplasty. Outcome measures were knee, calf and ankle swelling, knee flexion, pain and patient-reported knee function. RESULTS: Seventy per cent of the swelling had occurred before application of the stocking the day after surgery. Knee, calf and ankle swelling and knee flexion measured on days 2, 7, 14 and 30 showed no significant difference between the two groups. Maximum pain level at rest and at walking was similar for both groups during the observation period. Also, the Oxford knee score was similar between the two groups on days 14 and 30. CONCLUSION: We did not find any clinical effect using a medical elastic compression stocking after total knee arthroplasty. LEVEL OF EVIDENCE: I.

Early recovery after fast-track Oxford unicompartmental knee arthroplasty. 35 patients with minimal invasive surgery.

BACKGROUND AND PURPOSE: After total knee arthroplasty with conventional surgical approach, more than half of the quadriceps extension strength is lost in the first postoperative month. Unicompartmental knee arthroplasty (UKA) operated with minimally invasive surgery (MIS) results in less operative trauma. We investigated changes in leg-extension power (LEP) in the first month after MIS Oxford UKA and its relation to pain, knee motion, functional performance, and knee function. PATIENTS AND METHODS: In 35 consecutive Oxford UKA patients, LEP was measured 1 week before and 1 month after surgery together with knee motion, knee swelling, the 30-second chair-stand test, and Oxford knee score. Assessment of knee pain at rest and walking was done using a visual analog scale. RESULTS: 30 patients were discharged on the day after surgery, and 5 on the second day after surgery. LEP and functional performance reached the preoperative level after 1 month. Only slight postoperative knee swelling was observed with rapid restoration of knee flexion and function. A high level of pain during the first postoperative night and day fell considerably thereafter. None of the patients needed physiotherapy supervision in the first month after discharge. INTERPRETATION: Fast-track MIS Oxford UKA with discharge on the day after surgery is safe and leads to early recovery of knee motion and strength even when no physiotherapy is used.

Preoperative lateral subluxation of the patella is a predictor of poor early outcome of Oxford phase-III medial unicompartmental knee arthroplasty.

BACKGROUND AND PURPOSE: There is disagreement in the literature about the importance of patellofemoral joint degeneration and knee pain for the outcome of unicompartmental knee arthroplasty (UKA). We therefore investigated the importance of selected predictors including patellofemoral joint degeneration and the location of preoperative knee pain for the early outcome of UKA. PATIENTS AND METHODS: The study group comprised 260 consecutive patients from 5 hospitals who underwent Oxford UKA for anteromedial osteoarthritis. Data were collected at baseline and included pain location, radiologically observed degeneration of the patellofemoral joint including subluxation of the patella, intraoperative cartilage status of the patellofemoral joint, disease-specific knee status, and Oxford knee score (OKS). Outcomes were evaluated after 1 year using the OKS, global patient satisfaction, and global patient result. RESULTS: The average OKS score at baseline was 24 (SD 7), and it was 40 (SD 8) at the 1-year follow-up. 94% of the patients claimed improvement after the operation and 90% were satisfied with the UKA. Lateral subluxation of the patella was a predictor of poor outcome, and the preoperative OKS score was also a predictor of outcome. Full-thickness cartilage loss at any location gave a similar outcome to that with a normal or near-normal joint surface, and likewise, preoperative anterior knee pain was not a predictor of outcome. INTERPRETATION: We conclude that the good early outcome after UKA in this study is in line with the best reported results. Patellofemoral degeneration should not be considered a contraindication to Oxford UKA. Patients with lateral subluxation of the patella have an increased risk of a poor result after UKA and should preferably be offered a total knee replacement.