Erfahrungen mit medialen monokondylären Prothesen mit mobilem Plateau

Background

Unicompartmental knee arthroplasty (UKA) has become an accepted therapy for medial osteoarthritis. The main reasons for its popularity are the minimally invasive surgical technique and the reports of excellent long-term results including high patient satisfaction and good knee joint function especially in younger patients.

Objectives

The purpose of our retrospective study was to evaluate the physical activities of patients who had undergone an Oxford III medial UKA. Special attention was paid to implant positioning and osteoarthritis of the patellofemoral joint.

Materials and methods

Of 181 implanted Oxford III prosthesis, 136 (75.1%) could be followed up. The mean age at time of surgery was 65.2 years; the average time of follow-up was 4.2 years. In addition to a physical examination and x-ray, the following scores were obtained: WOMAC (Western Ontario and McMaster Osteoarthritis Index), OKS (Oxford Knee Score), KSS (Knee Society Score), UCLA activity and the Turba score.

Results

The majority of the patients (81%) returned to their sporting activity following knee surgery. Higher complication rates or progression of osteoarthritis associated with sporting activities were not observed. The active patients had significantly higher scores for the OKS, KSS, WOMAC, and UCLA scores. The correct implant position, especially avoiding overcorrection to valgus malalignment, is important for good clinical outcome.

Conclusion

Our results demonstrate that a high degree of patient satisfaction in terms of physical and sporting activity can be achieved using the Oxford III UKA for medial osteoarthritis without an increased risk for complications.     

Moderne unikondyläre Kniearthroplastik

Background

Unicondylar knee arthroplasty (UKA) is an established therapeutic option for advanced medial or lateral gonarthrosis.

Objectives

The cornerstones of a successful UKA, careful patient selection, preoperative planning and precise operation technique, are discussed in this overview article.

Importance

In contrast to total knee arthroplasty, UKA allows preservation of the contralateral and patellofemoral compartments as well as the cruciate ligaments and is often associated with rapid postoperative recovery, improved knee kinematics and knee function. However, UKA is technically very demanding. High revision rates have been reported in particular with widespread application, according to national joint replacement registries.

Conclusion

Successful UKA relies on meticulous patient selection, preoperative planning and surgical technique. It is justified to broaden classic UKA indications. In medial and lateral UKA three types of mechanical varus-valgus deformity can be encountered: type 1 (isolated intraarticular deformity), type 2 (pronounced deformity due to extraarticular varus deformity in medial UKA or valgus deformity in lateral UKA), type 3 (reduced deformity due to extraarticular valgus deformity in medial UKA or varus deformity in lateral UKA). We believe these deformities should be addressed accordingly with surgical technique.     

Does Interlimb Knee Symmetry Exist After Unicompartmental Knee Arthroplasty?

Background

Unicompartmental knee arthroplasty (UKA) has long been a treatment option for patients with disease limited primarily to one compartment with small, correctable deformities. However, some surgeons presume that normal kinematics of a lateral compartment UKA are difficult to achieve. Furthermore, it is unclear whether UKA restores normal knee kinematics and interlimb symmetry.

Questions/purposes

We determined knee kinematics exhibited during stair ascent by patients with medial- (MED-UKA) or lateral-UKA (LAT-UKA) and if the knee kinematics of the operated and nonoperated limbs were symmetrical.

Methods

Participants were 17 individuals with MED-UKA and nine with LAT-UKA, all with nondiseased contralateral limbs. For each limb, participants walked up four stairs for five trials while a motion-capture system obtained reflective marker locations. Temporal events were determined by force platform signals. Interlimb symmetry was classified for temporal gait and knee angular kinematics by comparing observed interlimb differences with clinically meaningful differences set at 5% of stride time for temporal variables and 5° for angular variables. The minimum postoperative followup was 6 months (median, 24 months; range, 6–53 months).

Results

Neither group demonstrated clinically meaningful mean interlimb differences. However, approximately half of participants of each UKA group displayed asymmetry favoring the operative or nonoperative limb with similar frequency.

Conclusions

Many patients undergoing UKA demonstrate kinematic interlimb symmetry during stair ascent. Interlimb asymmetry may be affected by a variety of factors unrelated to the UKA.

Clinical Relevance

A MED- or LAT-UKA can potentially restore normal knee function for a demanding task of daily life.     

Proximal Tibial Bone Density Is Preserved After Unicompartmental Knee Arthroplasty

Background

Bone mineral density (BMD) in the proximal tibia decreases after TKA and is believed to be a factor in implant migration and loosening. Unicompartmental knee arthroplasty (UKA) is a less invasive procedure preserving knee compartments unaffected by degeneration. Finite element studies have suggested UKA may preserve BMD and that implants of differing stiffnesses might differentially affect BMD but these notions have not been clinically confirmed.

Questions/purposes

We therefore asked whether (1) proximal tibial BMD decreases after UKA, and (2) a cemented metal tibial component with a mobile polyethylene (PE) bearing would have greater BMD loss than a cemented PE tibial component.

Methods

We prospectively followed 48 patients who underwent 50 UKAs using one of two implants: one with a cemented metal tibial baseplate and a mobile PE insert (n = 26) and one with a cemented all-PE tibial component (n = 24). In followup we assessed pain and function (Oxford Knee Score, SF-12, The Knee Society Score^©) and radiographs. BMD changes were assessed using quantitative CT osteodensitometry performed postoperatively and at 1 and 2 years after the index procedure.

Results

Mean cancellous BMD decreased 1.9% on the medial side and 1.1% on the lateral side. Mean cortical BMD was static, decreasing 0.4% on the medial side and increasing 0.5% on the lateral side. The greatest observed difference between implants for any region was 3.7%. There were no differences in pain or functional outcome scores.

Conclusions

BMD was preserved 2 years after UKA with no major differences seen between implant types.     

Feasibility and safety of performing outpatient unicompartmental knee arthroplasty

Purpose

Unicompartmental knee arthroplasty (UKA) has a faster short-term recovery than total knee arthroplasty (TKA). The purpose of this study was to determine the feasibility and safety of performing outpatient UKAs in a consecutive group of patients presenting with unicompartmental knee osteoarthritis.

Methods

A total of 105 consecutive patients underwent unicompartmental arthroplasty before noon with the intention of being discharged as an outpatient. All patients followed an established rapid recovery pathway to facilitate a same-day discharge. Post-operative complications and hospital readmissions were retrospectively recorded for all patients at one week and at three months after surgery.

Results

All of the 105 patients (100 %) indicated for outpatient UKA could be discharged home on the same day of surgery. No patients required readmission within the first week post-operatively, while one patient required readmission between week one and week 12. The single patient who required readmission developed a post-operative infection requiring irrigation/debridement with polyethylene liner exchange and intravenous antibiotics.

Conclusion

Using an established, multidisciplinary, rapid recovery protocol, outpatient UKA is safe and feasible in the vast majority of patients.     

In vivo kinematics of a robot-assisted uni- and multi-compartmental knee arthroplasty

Background

There is great interest in providing reliable and durable treatments for one- and two-compartment arthritic degeneration of the cruciate-ligament intact knee. One approach is to resurface only the diseased compartments with discrete unicompartmental components, retaining the undamaged compartment(s). However, placing multiple small implants into the knee presents a greater surgical challenge than total knee arthroplasty, so it is not certain that the natural knee mechanics can be maintained or restored. The goal of this study was to determine whether near-normal knee kinematics can be obtained with a robot-assisted multi-compartmental knee arthroplasty.

Methods

Thirteen patients with 15 multi-compartmental knee arthroplasties using haptic robotic-assisted bone preparation were involved in this study. Nine subjects received a medial unicompartmental knee arthroplasty (UKA), three subjects received a medial UKA and patellofemoral (PF) arthroplasty, and three subjects received medial and lateral bi-unicondylar arthroplasty. Knee motions were recorded using video-fluoroscopy an average of 13 months (6–29 months) after surgery during stair and kneeling activities. The three-dimensional position and orientation of the implant components were determined using model-image registration techniques.

Results

Knee kinematics during maximum flexion kneeling showed femoral external rotation and posterior lateral condylar translation. All knees showed femoral external rotation and posterior condylar translation with flexion during the step activity. Knees with medial UKA and PF arthroplasty showed the most femoral external rotation and posterior translation, and knees with bicondylar UKA showed the least.

Conclusions

Knees with accurately placed uni- or bi-compartmental arthroplasty exhibited stable knee kinematics consistent with intact and functioning cruciate ligaments. The patterns of tibiofemoral motion were more similar to natural knees than commonly has been observed in knees with total knee arthroplasty. Larger series are required to confirm these as general observations, but the present results demonstrate the potential to restore or maintain closer-to-normal knee kinematics by retaining intact structures and compartments.     

UKA in combination with PFR at average 12-year follow-up

Introduction

Safety and efficacy of unicompartmental knee arthroplasty (UKA) has been shown in large patient series. Patellofemoral replacement (PFR) is known to be a viable solution to end-stage patellofemoral arthritis. Bicompartmental osteoarthritis (OA) affecting the medial tibio-femoral and the patello-femoral compartment (medio-patellofemoral OA) is often treated with total knee arthroplasty (TKA). It was hypothesized that medio-patellofemoral OA can successfully be treated with bicompartmental arthroplasty.

Method

In a retrospective approach nine patients who had received UKA in combination with PFR were included into the study. Intact ACL and lateral compartment were conditions for the indication. Patients were clinically examined including clinical scores (KSS and WOMAC) and radiographies were evaluated. Satisfaction of patients was recorded under four categories.

Results

Average follow-up after bicompartmental arthroplasty was 11.8 ± 5.4 years (4–17 years). Among the nine patients there were eight females and one male at an average age at operation of 64 ± 5 years. No surgical revisions were required following bicompartmental arthroplasty. The KSS score increased from a preoperative 68.8 ± 26.2 to 175.5 ± 22.9 at latest follow-up (p = 0.002). WOMAC was 18.3 ± 8.6 at latest follow-up. All patients included were satisfied (n = 3) or very satisfied (n = 6) with the outcome of this surgical procedure.

Conclusion

This small case series shows that a bicompartmental arthroplasty can be a successful approach to prevent or postpone TKA. However, this intervention is technically demanding and requires experience in both UKA and PFR.     

The Role of Patient Characteristics on the Choice of Unicompartmental versus Total Knee Arthroplasty in Patients With Medial Osteoarthritis

Background

Medial unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) are both viable treatment options for medial osteoarthritis (OA). However, it remains unclear when to choose for which arthroplasty treatment. Goals of this study were therefore to (1) compare outcomes after both treatments and (2) assess which treatment has superior outcomes in different patient subgroups.

Outcome of Unicondylar Knee Arthroplasty vs Total Knee Arthroplasty for Early Medial Compartment Arthritis: A Randomized Study

Background

With increasing number of patients with early osteoarthritis of knee opting for total knee arthroplasty (TKA), there has been increase in patients dissatisfied with surgical outcomes. It is being presumed that offering unicondylar knee arthroplasty (UKA) to them would improve outcomes.

Preoperative Patient-Recorded Outcome Measures Predict Patient Discharge Location Following Unicondylar Knee Arthroplasty

Background

Advantages of unicondylar knee arthroplasty (UKA) over total knee arthroplasty include rapid recovery and shorter lengths of stay following surgery. Patients requiring extended postoperative care fail to recognize these benefits. Patient-reported outcome measures have proved useful in predicting outcomes following joint arthroplasty. The purpose of this study was to identify and report preoperative patient-reported outcome measures and clinical variables that predict discharge to skilled nursing facilities following UKA.

Differences in Patient-Reported Outcomes Between Unicompartmental and Total Knee Arthroplasties: A Propensity Score-Matched Analysis

Background

The purpose of this study was to compare the patient-reported outcomes regarding joint awareness, function, and satisfaction after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA).

Impact of patellar height on unicompartment knee arthroplasty: does patella baja lead to an inferior outcome?

Background

Though a number of series with long-term results have been published, there is still a paucity of literature on the role of patellar height after unicompartment knee arthroplasty (UKA). The present study was conducted with a hypothesis that patella baja may lead to a poor outcome at follow-up.

Materials and methods

A retrospective review of 134 knees was performed and patellar height calculated before and after UKA by Blackburne-Peel index (BPI) and the Insall-Salvati ratio (ISR) on true lateral radiographs of the patients in 30° of flexion taken pre-operatively and at 1 year, 2 years and final follow-up (minimum 5 years). Statistical analysis was performed to evaluate the outcomes.

Results

There was a decrease in ISR in 14.18 % and in BPI in 19.4 % at final follow-up. There was a significant decrease in BPI values while the decrease was not significant for ISR. After eliminating the pre-operative patella baja, 7.3 % developed post-operative patella baja, according to ISR, while 11.5 % developed patella baja as per BPI. At final follow-up there was a statistically significant decrease in stair climbing scores in patients with patella baja when compared to patients with normal ISR.

Conclusion

Patients with a decrease in patellar height as per ISR have a decrease in stair climbing score at mid-term follow-up while the overall KSS, and pain scores are not affected by a change in patellar height and neither is there a significant progress in patellofemoral osteoarthritis among patients with patella baja compared to normal patella.     

Reduziert ein erh?hter tibialer Slope den Abrieb bei unikondyl?ren Schlittenprothesen?

Introduction

Unicompartmental knee arthroplasty (UKA) has become a standard procedure with good clinical outcome in patients with isolated medial osteoarthritis of the knee. However, the survival rates of UKA are still inferior compared to that of total knee arthroplasty. Aseptic loosening and wear are responsible for more than 50% of revisions. Therefore, this study evaluated the influence of the tibial slope on the wear rate in a medial UKA.

Materials and methods

The wear rate of a medial mobile-bearing UKA (Univation? Aesculap, Tuttlingen, Deutschland) was evaluated according to the ISO 14243-1:2002(E) norm with a customized four-station servo-hydraulic knee wear simulator (EndoLab, Thansau, Germany). In the first group, the prostheses was medially implanted with 0° slope (n?=?3) and in the second group the prostheses was medially implanted with 8° slope (n?=?3). The lateral side was kept constant with 0° in both groups. For each implant, a total of 5.0 million cycles was performed and after every 0.5 million cycles the gravimetric wear rate was determined.

Results

The wear rate in the 0° slope group was 3.46?±?0.59?mg/million cycles and therefore significantly higher than in the 8° slope group with 0.99?±?0.42?mg/million cycles (p?Discussion An increase in the tibial slope leads to a reduced wear rate in a mobile-bearing UKA. Therefore, at least for this mobile-bearing UKA a higher tibial slope seems favorable to reduce the wear. However, before an optimal position of the tibial slope can be recommended, further investigations are required to evaluate the influence of the tibial slope on other factors, such as the ligament tension or the strain on the lateral compartment.     

The Survivorship and Clinical Results of Minimally Invasive Unicompartmental Knee Arthroplasty at 10-Year Follow-up

Background

In this study, we investigated the long-term clinical results and survival rate of minimally invasive unicompartmental knee arthroplasty (UKA) by collecting cases that had been implanted more than 10 years ago.

Methods

One hundred and twenty-eight patients (166 cases) who underwent Oxford phase 3 medial UKA using the minimally invasive surgery from January 2002 to December 2002 were selected. The mean age of the patients at the time of surgery was 61 years, and the duration of the follow-up was minimum 10 years. Clinical and radiographic assessments were performed using the Knee Society clinical rating system, and the survival analysis was done by the Kaplan-Meier method with 95% confidence interval (CI).

Results

The mean Knee Society knee and function scores improved significantly from 53.8 points (range, 25 to 70 points) and 56.1 points (range, 35 to 80 points) preoperatively to 85.4 points (range, 58 to 100 points) and 80.5 points (range, 50 to 100 points) at 10-year follow-up, respectively (p < 0.001). Failures following the UKA occurred in 16 cases (9.6%), and the mean time of the occurrence of the failure was 6.2 years after the surgery. The 10-year survival rate was 90.5% (95% CI, 85.9 to 95.0) when failure was defined as all the reoperations, whereas the 10-year survival rate was 93.4% (95% CI, 89.6 to 97.1) when the cases in which only revision total knee arthroplasty was defined as failure.

Conclusions

The results of this study show outstanding functions of the knee joint and satisfactory 10-year survival rate after minimally invasive UKA. Therefore, minimally invasive UKA could be a useful method in the treatment of osteoarthritis in one compartment of knee joint.     

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.After total knee arthroplasty (TKA), more than half of the preoperative quadriceps strength is lost in the first month after surgery (Mizner et al. 2005). TKA surgery with minimally invasive surgery (MIS) may lead to less postoperative pain, shorter length of stay in hospital, and greater knee flexion (Chen et al. 2006), and the MIS approach may result in better outcome with regard to maintaining extensor strength than the conventional surgical approach (Kim et al. 2010). In unicompartment knee arthrosis, the Oxford Group recommend unicompartmental knee arthroplasty (UKA) operated with MIS, since recovery is twice as fast as after the conventional approach and damage to the soft tissue of the joint is greatly diminished (Price et al. 2001). Althrough fast-track UKA with length of stay of about 1.5 days has been described (Reilly et al. 2005), there have been few reports on quadriceps strength after UKA (Mancher et al. 2002) and to our knowledge there have been no reports on early leg-extension power (LEP) after UKA.We studied changes in LEP within the first month after fast-track MIS Oxford Phase III medial UKA in relation to pain, knee motion, functional performance, knee function, and the need for physiotherapy after discharge.     

Comparison of three different tourniquet application strategies for minimally invasive total knee arthroplasty: a prospective non-randomized clinical trial

Introduction

It is still controversial on the optimal timing of tourniquet used in total knee arthroplasty (TKA). Most previous studies focused on the comparison of different tourniquet application in controversial TKA, while the aim of our work was to compare three strategies of tourniquet application in minimally invasive TKA.

Materials and methods

90 patients were enrolled in this study. Based on the different tourniquet application strategies, they were divided into three groups. Group A: using tourniquet during the whole surgery; Group B: tourniquet inflated before incision and deflated after the hardening of the cement; Group C: using tourniquet during the cementation. Blood loss and serum levels of C-reactive protein, IL-6, creatine kinase and myoglobin were checked preoperatively. The HSS knee score, VAS pain score, range of motion (ROM), limb swelling and hospital stays were also recorded.

Results

The mean levels of Hb and Hct were lower in Group C (104.2 ± 10.4 g/L, 31.8 ± 3.2 %) than those in Groups A (111.4 ± 14.4 g/L, p = 0.035; 34.1 ± 4.1 %, p = 0.032) and B (112.8 ± 14.3 g/L, p = 0.013; 34.5 ± 3.7 %, p = 0.011) immediately after the surgery. Compared with Groups A and B, both serum inflammation and muscle damage markers were lower in Group C. There were no significant differences between the groups in terms of HSS knee score, ROM, estimated blood loss, swelling ratio, VAS pain score and hospital stays.

Conclusions

Using a tourniquet full time in minimally invasive TKA causes less intraoperative blood loss and more excessive inflammation and muscle damage. However, the advantage of part-time using tourniquet did not show in early functional outcomes.     

Minimally invasive total hip arthroplasty: a randomized controlled prospective trial

Introduction

Advantages of minimally invasive total hip arthroplasty (THA) are controversially discussed.

Method

In this prospective study 51 patients (52 hips) were randomly allocated to a classical lateral or a minimally invasive approach (modification of the Hardinge-approach). Operating time, intraoperative blood loss, postoperative hemoglobin, muscle enzymes CK and myoglobin were recorded. Radiologically the positioning of the prosthesis was analyzed. WOMAC- and Harris Hip Score (HHS) were assessed preoperatively, at discharge, at 6 weeks and 3 months.

Results

In the minimally invasive group there was a shorter length of surgery, the scores in the WOMAC and HHS were slightly better at discharge and at the 3 months- examination, myoglobin-rise was slightly less. The positioning of the prosthesis was good in both groups. Minimally invasive THA led to a quicker recovery, at 3 months postoperative there was still a slight difference to the standard group.

Conclusion

If these slight differences subside has to be examined in studies with a longer follow-up.     

Patterns of Compartment Involvement in End‐stage Knee Osteoarthritis in a Chinese Orthopedic Center: Implications for Implant Choice

Objectives

Knee osteoarthritis (OA) is a prevalent disease in the elderly, causing pain and contributing to poor quality of life. Surgical intervention, such as knee arthroplasty, can be used in those with end‐stage knee OA. Total knee arthroplasty (TKA) is one of the most common surgical procedures for end‐stage knee OA, with promising clinical outcomes. However, a large proportion of patients with isolated compartment OA can be treated with unicompartmental knee arthroplasty (UKA) instead. UKA has shown better patient‐reported functional outcomes, and lower mortality and major complication rates than TKA. The percentage of UKA in knee arthroplasty varied in different orthopedic centers, and we believed that the requirement for UKA was underestimated in many centers. A retrospective study was carried out on our Chinese patient population presenting for knee arthroplasty; it aimed to identify the proportion of patients that might be suitable for UKA.

Methods

A retrospective cross‐sectional study of 155 consecutive patients (168 knees) awaiting TKA for end‐stage primary OA was performed. The pattern and grade of OA was recorded from preoperative weight‐bearing anteroposterior and non‐weight‐bearing lateral radiographs. The medial, lateral, patellofemoral compartment was given an individual Kellgren–Lawrence grade on the radiographs, and those grade ≥3 were defined as end‐stage OA. The compartments involvement was established then. The integrity of the anterior cruciate ligament (ACL) was determined by the modified Keyes classification on lateral radiographs. The applicability for total or partial knee arthroplasty was determined according to the compartments involvement.

Results

Medial compartment involvement was found in 154 (91.7%) knees, while the involvement of the lateral compartment and patellofemoral joint was found in 54 (32.1%) and 57 (33.9%) knees, respectively. Eighty‐one (48.2%) of the knees showed medial compartment OA with or without patellofemoral joint involvement, and modified Keyes classification grade 1, indicating an intact ACL, and, hence, potential suitability for medial UKA. Isolated lateral OA indicating possible suitability for lateral UKA was identified in 11 knees (6.5%). No patients showed isolated patellofemoral joint OA. The other 76 (45.2%) knees could be treated by TKA.

Conclusions

The medial compartment was the most commonly affected in our Chinese patients indicated for knee arthroplasty. More than half of the patients in this group could be treated by either medial or lateral UKA.