Minimally invasive surgery vs conventional exposure using the Miller-Galante unicompartmental knee arthroplasty: a randomized radiostereometric study

Functional scores and prosthetic implant placement are different for navigated medial UKA left in varus alignment

PURPOSE

The purpose of this study was to analyze the clinical outcomes and radiologic position of the knee in two groups of patients after medial unicompartmental knee arthroplasty (UKA): one group with residual varus axis (RVA) alignment and other one with neutral mechanical axis (NMA) of the lower limb.

METHODS

All patients who underwent UKA between January 2015 and January 2018 were evaluated retrospectively. Inclusion criteria were: medial UKA for isolated medial femoro-tibial osteoarthritis, a varus deformity of < 15°, and a minimal follow-up of 2 years. All patients had a preoperative and postoperative clinical examination with functional scores (New International Knee Score (NewIKS) and Knee injury and Osteoarthritis Outcome Score (KOOS) and radiographs. Preoperative and postoperative values for continuous outcomes were compared using the Student's t test for paired data and differences between the groups were compared with the Mann-Whitney U test. p < 0.05 was considered statistically significant.

RESULTS

The RVA group consisted of 48 cases of medial UKA in 48 patients (22 females). Mean postoperative hip-knee-ankle (HKA) angle was 174.3° ± 2.8 and the corresponding mean AKI angle (tibial mechanical angle) was 82.9° ± 2.9. The NMA group consisted of 35 cases of medial UKA in 35 patients (14 females). Mean postoperative HKA angle was 178.9° ± 3 and the corresponding mean AKI angle was 85.5° ± 3.1. A significant difference was found between the two groups for the KOOS score and for global NewIKS, with a better score in the RVA group.

CONCLUSIONS

RVA alignment after medial UKA results in a significant improvement in functional knee scores at 2-year post-surgery. Return to sport and recreational activities was better than in patients with postoperative NMA.

LEVEL OF EVIDENCE

Level 3; retrospective cohort study.

Determination of the Accuracy of Navigated Kinematic Unicompartmental Knee Arthroplasty: A 2-Year Follow-Up

BACKGROUND

Unicompartmental knee arthroplasty (UKA) lacks history of patient satisfaction and research addressing technique validity. The aim of this study was to determine minimally invasive navigated kinematic UKA accuracy by comparing postoperative limb alignment with preoperative stress values.

METHODS

A single-center retrospective study was conducted on 53 consecutive patients (postoperative alignment: varus n = 51, valgus n = 2) who underwent computer navigation assisted UKA. Two patient groups (A and B) predetermined by joint deformity cut-off points (B included valgus deformity) underwent preoperative magnetic resonance imaging and x-ray evaluation to assess limb alignment and exclude lateral and patellofemoral osteoarthritis. Preoperative and postoperative joint alignment, stress value, and range of movement were recorded with navigation. Outcome measures include comparison of postoperative alignment to the preoperative stress values for varus and valgus postoperative alignment groups and preoperative and/or postoperative Western Ontario and McMaster Universities and Knee Society Score evaluations.

RESULTS

Minor systematic bias was found between stress value and postoperative alignment; however, the magnitude of difference was clinically acceptable. Score evaluations, prosthesis size or alignment didn't differ between groups. Furthermore, there was no significant increase in range of movement at 2 years. There was a high degree of agreement between stress value and postoperative alignment values suggesting strong validity for the surgical technique to determine optimal postoperative alignment.

CONCLUSION

This study validates our surgical technique. Minimally invasive navigated UKA allows us to predict predisease alignment and recreates it with high accuracy. Our clinical results at 2 years are comparable with other published data.

Mid-term results of Oxford phase-3 medial unicompartmental knee arthroplasty for medial arthritis in Chinese patients

BACKGROUND

The purpose of this study was to evaluate the mid-term results of an Oxford phase-3 unicompartmental knee arthroplasty (UKA) for medial arthritis in Chinese patients.

METHODS

The study included 64 patients who underwent a minimally invasive Oxford phase-3 UKA for medial knee arthritis. The patients were clinically evaluated preoperatively and at the final follow-up according to the clinical and functional components of the Knee Society Score (KSS), the Hospital for Special Surgery knee score and range of motion. A Kaplan-Meier survivorship analysis was performed with revision surgery as the end point.

RESULTS

The mean preoperative clinical KSSs increased from 63.2 to 91.4 post-operatively, and the mean functional KSSs increased from 54.9 to 86.5 post-operatively. In addition, the mean Hospital for Special Surgery scores increased from 59.5 to 86.4. The mean active knee flexion increased from 109.1° preoperatively to 123.6° post-operatively. A total of six patients (six knees) required revision surgery at the time of the maximum 10-year follow-up. Four conversions to total knee arthroplasty were performed because of arthritis progression in the lateral compartment. One revision to total knee arthroplasty was performed for aseptic loosening, and one liner exchange was performed for wear. The cumulative survival rates at the 6- and 8-year follow-ups were 97% and 93%, respectively.

CONCLUSION

Oxford phase-3 UKA was largely applicable for medial arthritis in Chinese patients. However, the Oxford phase-3 medial UKA selection criteria for young Chinese males need further exploration to obtain the best treatment effect.

Roentgen stereophotogrammetric analysis: an effective tool to predict implant survival after an all-poly unicompartmental knee arthroplasty-a 10 year follow-up study

PURPOSE

The main purpose of the present study was to determine long-term implant fixation of 15 unicompartmental knee arthroplasty (UKAs) with an all-poly tibial component using Roentgen stereophotogrammetric analysis (RSA) at a mean 10-year follow-up. The secondary purpose was to investigate whether the progressive loss of implant's fixation correlates with a reduction in Knee society score (KSS).

METHODS

Fifteen non-consecutive patients with primary knee osteoarthritis received a UKA with an all-poly tibial component were assessed using KSS scores pre-operatively and post-operatively and RSA on day 2 after surgery, then at 3, 6, and 12 months and yearly thereafter. The mean last follow-up was 10 years.

RESULTS

An increase in maximum total point motion (MTPM) values from 6 months to 1 year post-operatively was found respect to post-operative reference. Implants' displacement values were always <2 mm during the first 6 months, and then, two different trends were noticed in revised and non-revised implants. MTPM increase between 1 and 2 years of follow-up in non-revised UKAs was always <0.2 mm, whereas it was >0.2 mm in revised UKAs. A linear and negative correlation with statistical significance was found between MTPM and both clinical and functional KSS scores (p < 0.001).

CONCLUSION

Also in a long-term follow-up evaluation, RSA is an effective tool to predict functional results after an all-poly UKA providing also a relevant predictive value at 1 year follow-up, and this can be very useful for both patients and surgeons.

LEVEL OF EVIDENCE

Diagnostic studies, Level III.

Adherence of hip and knee arthroplasty studies to RSA standardization guidelines. A systematic review

BACKGROUND AND PURPOSE

Guidelines for standardization of radiostereometry (RSA) of implants were published in 2005 to facilitate comparison of outcomes between various research groups. In this systematic review, we determined how well studies have adhered to these guidelines.

METHODS

We carried out a literature search to identify all articles published between January 2000 and December 2011 that used RSA in the evaluation of hip or knee prosthesis migration. 2 investigators independently evaluated each of the studies for adherence to the 13 individual guideline items. Since some of the 13 points included more than 1 criterion, studies were assessed on whether each point was fully met, partially met, or not met.

RESULTS

153 studies that met our inclusion criteria were identified. 61 of these were published before the guidelines were introduced (2000-2005) and 92 after the guidelines were introduced (2006-2011). The methodological quality of RSA studies clearly improved from 2000 to 2011. None of the studies fully met all 13 guidelines. Nearly half (43) of the studies published after the guidelines demonstrated a high methodological quality and adhered at least partially to 10 of the 13 guidelines, whereas less than one-fifth (11) of the studies published before the guidelines had the same methodological quality. Commonly unaddressed guideline items were related to imaging methodology, determination of precision from double examinations, and also mean error of rigid-body fitting and condition number cutoff levels.

INTERPRETATION

The guidelines have improved methodological reporting in RSA studies, but adherence to these guidelines is still relatively low. There is a need to update and clarify the guidelines for clinical hip and knee arthroplasty RSA studies.

Revision of unicompartmental knee arthroplasty: implants used and causes of failure

Objective

to determine the causes of unicondylar knee arthroplasty failures, as well as identify the implants used and the need of bone grafting in patients undergoing revision UKA in Center of Knee Surgery at the Instituto Nacional de Traumatologia e Ortopedia (INTO) in the period between January 1990 and January 2013.

Methods

a retrospective analysis of the medical documentation and imaging, determining the cause of failure of UKA and the time of its occurrence, as well as prosthetic components implanted during the review and the need for bone grafting.

Results

in this study, 27 UKA failures in 26 patients were included. Collapse of one or more components was the main cause of failure, occurring in 33% of patients. Aseptic failure was identified in 30% of cases, progression of osteoarthrosis in 15%, infection and pain 7% each, and osteolysis and polyethylene failure in 4% each. Early failure occurred in 41% of all revisions of UKA and late failure in 59%. 23 patients have undergone revision of UK.

Conclusion

in 35% of revisions the use of bone grafting was needed in tibial area; in 3 cases we needed allograft from Tissue Bank. We did not use metal increase in any of the revision. In one patient we used implant constraint for instability.

Minimally invasive surgery did not improve outcome compared to conventional surgery following unicompartmental knee arthroplasty using local infiltration analgesia: a randomized controlled trial with 40 patients

BACKGROUND AND PURPOSE

There has recently been interest in the advantages of minimally invasive surgery (MIS) over conventional surgery, and on local infiltration analgesia (LIA) during knee arthroplasty. In this randomized controlled trial, we investigated whether MIS would result in earlier home-readiness and reduced postoperative pain compared to conventional unicompartmental knee arthroplasty (UKA) where both groups received LIA.

PATIENTS AND METHODS

40 patients scheduled for UKA were randomized to a MIS group or a conventional surgery (CON) group. Both groups received LIA with a mixture of ropivacaine, ketorolac, and epinephrine given intra- and postoperatively. The primary endpoint was home-readiness (time to fulfillment of discharge criteria). The patients were followed for 6 months.

RESULTS

We found no statistically significant difference in home-readiness between the MIS group (median (range) 24 (21-71) hours) and the CON group (24 (21-46) hours). No statistically significant differences between the groups were found in the secondary endpoints pain intensity, morphine consumption, knee function, hospital stay, patient satisfaction, Oxford knee score, and EQ-5D. The side effects were also similar in the two groups, except for a higher incidence of nausea on the second postoperative day in the MIS group.

INTERPRETATION

Minimally invasive surgery did not improve outcome after unicompartmental knee arthroplasty compared to conventional surgery, when both groups received local infiltration analgesia. The surgical approach (MIS or conventional surgery) should be selected according to the surgeon's preferences and local hospital policies. ClinicalTrials.gov. (Identifier NCT00991445).

Minimally invasive versus conventional unicompartmental knee arthroplasty

INTRODUCTION

Unicompartmental knee arthroplasty (UKA) has been proven to be a viable procedure in case of medial osteoarthritis of the knee joint. Minimally invasive surgery (MIS) techniques have been described to facilitate recovery after surgery. The aim of this study was to rule out major failure mechanisms and to obtain clinical data for comparison between a conventional and the MIS approach.

MATERIALS AND METHODS

A consecutive series of 163 UKA (160 patients) were retrospectively included (83 conventional and 80 MIS interventions). Patients were invited for a clinical examination including clinical scores (KSS, Lequesne, UCLA, VAS, Feller- and Turba Patella Scores). Seven patients (4.3%) were lost to follow-up.

RESULTS

Average follow-up was 4.6 ± 1.3 (1.5-6.8) years. Average age at operation was 67.5 ± 7.9 (45-81) years. Fifteen implants had been converted to TKA (9.2%). There were seven conversions to TKA in the MIS and 8 in the conventional group. Of the applied clinical scores there were better values for the Turba patella score in the MIS group. Differences of the other scores were not statistically significant.

CONCLUSION

Comparable functional results for both UKA procedures could be shown. There were no significant differences in terms of clinical scores or revision rates. The MIS approach in medial UKA did not show any major complications. Its use seems to be safe.

The practice of unicompartmental knee arthroplasty in the United Kingdom

PURPOSE

To survey the current practice of unicompartmental knee arthroplasty (UKA) in the United Kingdom.

METHODS

Questionnaires were sent to all 341 local members of the British Association for Surgery of the Knee to inquire into their practice of UKA, including clinical indications, preoperative investigations, surgical approach, preferences in implant design, and the role of UKA in relation to high tibial osteotomy.

RESULTS

56% of respondents performed less than 16 UKAs per year, whereas 16.5% performed over 30 per year. 89.5% of the respondents used anteroposterior radiographs as their main investigation tool. Only 30% and 16.5% used posteroanterior 30 degrees flexion and varus/valgus stress radiographs, respectively, despite being better investigation tools. 57% considered arthroscopy, despite its invasive nature. The main contra-indications to UKA were anterior cruciate ligament deficiency with instability (95%), focal grade-III osteoarthritis in the contralateral compartment (87%), and osteoporosis with rheumatoid arthritis (80.5%), but only 59% of respondents considered an inability to passively correct a pre-existing varus or valgus deformity as a contra-indication. 51.5% of respondents preferred minimally invasive approach, 96% preferred cemented fixation, and over two thirds used the mobile bearing design. 72% of respondents expressed preference for total knee arthroplasty over UKA in localised lateral compartment osteoarthritis.

CONCLUSION

Modern UKA has gained popularity in properly selected patients with localised medial compartment osteoarthritis, provided the knee is not anterior cruciate ligament deficient and any deformity is passively correctable.

The Repicci II® unicondylar knee arthroplasty: 9-year survivorship and function

BACKGROUND

Unicompartmental knee arthroplasty (UKA) is a recognized procedure for treatment of medial compartment osteoarthritis. UKA using minimally invasive surgery (MIS) has the theoretical advantage of less bone resection and quicker rehabilitation. Whether the function of patients with UKA compares with that of patients with conventional TKA is unclear.

QUESTIONS/PURPOSES

We determined (1) the length of stay and complications associated with a short-stay MIS protocol; (2) whether MIS techniques allow for accurate positioning of the implant and alignment of the limb; (3) the change in functional scores; (4) the revision rate, reasons for revision, and survival of this implant.

PATIENTS AND METHODS

We prospectively followed 100 patients who had 114 UKAs. All completed an International Knee Society (IKS) score preoperatively, at 1 year, and at last followup. We determined survivorship. Minimum followup was 5.2 years (mean, 7.4 years; range, 5.2-9 years).

RESULTS

Mean length of stay was 1.2 days, with 41% discharged the same day. The perioperative complication rate was 6%. The mean IKS score improved from 77 to 93 and was 86 at last followup. The mean hip-knee-ankle axis changed from 6° varus to 1.7° varus. Twenty-two patients underwent a revision procedure at a mean 6.2 years after the index procedure. Survivorship of the prosthesis was 78% at 9 years.

CONCLUSIONS

The short-stay protocol was not associated with a high perioperative complication rate. This technique is associated with improvement in function and restoration of limb alignment, allowing accurate positioning of the implant. Compared with other reports of survival of UKA, this implant had a lower survivorship and increased revision rate.

Scientific evidence for the use of modern unicompartmental knee arthroplasty

Unicompartmental knee arthroplasty as a surgical treatment for monocompartmental knee arthritis remains a controversial procedure with questions surrounding the benefits and survivorship of the procedure versus osteotomies or total knee arthroplasties. The authors, by examining the complete body of literature for scientific evidence concerning the procedure, will describe the history of usage of these prostheses, their rationale for usage, modern devices and their results, and why they may have advantages as a treatment modality for monocompartmental knee arthritis. Outcomes of current unicompartmental designs will be presented and evaluated to determine which aspects of the design and patient selection technique are associated with success or failure. Commonly asked questions regarding the use of these devices will be addressed. The authors will also describe some potential modifications that might affect the use of these components in the future, including minimally invasive procedures and robotics, and how these devices may change over the next 5 years.

Medial unicompartmental knee arthroplasty with Miller-Galante II prosthesis: mid-term clinical and radiographic results

AIM

The purpose of our study was to evaluate retrospectively the mid-term results of the Miller-Galante II (Zimmer, Warsaw, USA) unicondylar knee arthoplasty (UKA).

METHOD

The study included 46 patients with medial UKAs. Mean follow-up time was 7.0 years (range 2.7-13.1 years).

RESULTS

Survival rate of the prosthesis was 86.6% (95% CI 73.7-99.6) at 7 years. The mean clinical and functional Knee Society Scores had increased from 51 and 62 points preoperatively to 76 and 93 points (P < 0.001) postoperatively. Five of the 46 knees were revised because of excessive wear of the polyethylene liner, and three due to progression of the osteoarthritis in the lateral compartment of the knee.

CONCLUSION

Survival of this fixed-bearing UKA was not as good as previously reported and polyethylene wear seems to be a more common problem than previously assumed.

Reduced hospital stay, morphine consumption, and pain intensity with local infiltration analgesia after unicompartmental knee arthroplasty

BACKGROUND AND PURPOSE

The degree of postoperative pain is usually moderate to severe following knee arthroplasty. We investigated the efficacy of local administration of analgesics into the operating area, both intraoperatively and postoperatively.

METHODS

40 patients undergoing unicompartmental knee arthroplasty (UKA) were randomized into 2 groups in a double-blind study (ClinicalTrials.gov identifier: NCT00653926). In group A (active), 200 mg ropivacaine, 30 mg ketorolac, and 0.5 mg epinephrine (total volume 106 mL) were infiltrated intraoperatively into the soft tissue, while in group P (placebo), no injections were given. 21 hours postoperatively, 150 mg ropivacain, 30 mg ketorolac, and 0.1 mg epinephrine were injected intraarticularly via a catheter in group A, whereas patients in group P were injected with the same volume of saline (22 mL).

RESULTS

Median hospital stay was shorter in group A than in group P: 1 (1-6) days as opposed to 3 (1-6) days (p < 0.001). Postoperative pain in group A was statistically significantly lower at rest after 6 h and 27 h and on movement after 6, 12, 22, and 27 h. Morphine consumption was statistically significantly lower in group A for the first 48 h, resulting in a lower frequency of nausea, pruritus, and sedation. Postoperatively, there were improved functional scores (Oxford knee score and EQ-5D) in both groups relative to the corresponding preoperative values.

INTERPRETATION

Local injection of analgesics periarticularly at the end of the operation and intraarticularly at 21 h postoperatively provided excellent pain relief and earlier home discharge following UKA. There was a high degree of patient satisfaction in both groups after 6 months (Clinical Trials.gov: NCT 00653926).

Comparison of minimally invasive unicompartmental knee arthroplasty with or without a navigation system

The authors investigated the hypothesis that navigation system-assisted minimally invasive unicompartmental knee arthroplasty (NA-MIS UKA) produces better short-term clinical results than MIS UKA without a navigation system. After a minimum 2-year follow-up, short-term functional results and component alignment accuracies of 31 knees that underwent NA-MIS UKA (the NA-MIS group) were compared with those of 33 knees that underwent MIS UKAs without a navigation system (the MIS group). The Hospital for Special Surgery and Western Ontario and McMaster Universities Osteoarthritis Index scores of 2 groups showed significant improvement at final follow-ups, but no significant intergroup differences were observed (P = .071 and P = .096, respectively). However, NA-MIS UKA produced more improvement in the desired mechanical axis and a lower percentage of prosthetic alignment outliers than MIS UKA.

Minimally invasive surgery of the knee

Minimally invasive knee replacement surgery has been developed in an attempt to lessen the impact of operations on the patient's quality of life, in the same way as arthroscopy, the forefather of minimally invasive surgery (MIS), revolutionised cartilage and ligament surgery three decades earlier. The technique is based on minimising soft tissue and muscle trauma, skin incision length, and capsular disruption while trying to maintain the ultimate goal of a well-aligned, well-fixed knee replacement. Short-term advantages including accelerated recovery and reduction in blood loss have been demonstrated, but it remains to be investigated whether MIS is able to provide sustainable benefits and long-term outcome equivalent to conventional surgery. Successful application of MIS techniques have been confirmed in conjunction with unicompartmental knee arthroplasty (UKR) implantation, while its use with total knee arthroplasty remains experimental. Critics have expressed concern that reduced visibility may compromise implant positioning and leg alignment which could have a negative effect on prosthetic long-term survival. MIS clearly represents a unique and more technically demanding procedure, but the learning curve may perhaps overshadow the benefits. Computer navigation may help to avoid such problems but so far scientific evidence regarding definitive outcomes is lacking, and some of the MIS techniques are still in the early phases of development.

Unicompartmental knee arthroplasty: technique through a mini-incision

Unicompartmental knee arthroplasty is a logical procedure when the lesion is limited to one femorotibial compartment. The procedure can now be performed through a mini-incision to provide quicker recovery because the extensor mechanism disruption is minimized. We have found the length of the incision varies according to patient mass and muscle tone. Specific instrumentation limited to the replaced compartment and using either an intra- or extramedullary femoral technique provides femorotibial component alignment and allows slight undercorrection of the deformity. Radiographic assessment demonstrates precise implantation of the components is possible with a mini-incision, which is believed important for the long-term results of the arthroplasty. The functional evaluation of patients implanted with unicompartmental knee arthroplasty performed through a mini-incision suggests appropriate kinematics can be restored after the procedure, enhancing the importance of a functional anterior cruciate ligament.

LEVEL OF EVIDENCE

Level V, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The ugly underbelly of the MIS movement: in the affirmative

Minimally invasive surgery (MIS) for hip or knee arthroplasty has been a recent rage in orthopedics. However, there are no substantial data supporting the use of these techniques, and multiple articles document increased risk of complications with MIS technique. Unfortunately, a huge marketing effort on the part of the implant industry and many surgeons is creating pressure on surgeons to sacrifice the quality of outcome for purported improved cosmesis or shorter length of hospital stay. This review examines the data from prospective studies evaluating the outcomes of MIS techniques and implores the surgeon to place quality before decreased incisional quantity!

Unicompartmental knee arthroplasty: functional recovery and radiographic results with a minimally invasive technique

We prospectively evaluated 100 consecutive unicompartmental knee arthroplasties, performed in minimally invasive quadriceps-sparing fashion, for medial compartment osteoarthritis in patients aged 46 to 79 years, with anteromedial tibial wear, less than 10 degrees of flexion contracture, correctable varus not exceeding 15 degrees , and an intact anterior cruciate ligament. We aimed to determine (1) early functional outcome and (2) radiographic limb alignment and component placement. Mean incision length was 7.2 cm, hospital stay 2.1 days, and blood loss 240 ml. Flexion at 3 months was between 120 degrees and 155 degrees (mean, 139 degrees ). Among the patients, 80% could flex beyond 130 degrees , and 91% could sit cross-legged, kneel, and get up easily from the floor. The mean hip-knee-ankle axis was 177 degrees . Ninety-five percent of femoral components were centered on the tibial component. Tibial component slope was restored in 91%.

Clinical experience using a minimally invasive surgical approach for total knee arthroplasty: early results of a prospective randomized study compared to a standard approach

There has been recent attention concerning minimally invasive techniques for knee arthroplasty. It is not clear whether these complicated techniques can be reproduced across multiple centers and for all surgeons. This prospective, randomized, multicenter study was carried out to assess safety and efficacy of a minimally invasive total knee arthroplasty. The study consisted of 80 knees. There were no differences in blood loss, operative time for completion of surgery, infection, and ultimate wound healing. There were 4 knees with delayed wound healing in the minimally invasive surgical technique group versus 1 in the standard group, which did not affect outcome. Early clinical and radiographic results were also indistinguishable. At 12 weeks follow-up, there was no difference in mean Knee Society objective and functional scores. In summary, in this study, minimal incision total knee arthroplasty demonstrated no improvement over a standard approach.