The anterior cruciate ligament-deficient knee and unicompartmental arthritis

Fixed-Bearing Lateral Unicompartment Knee Arthroplasty in Degenerative ACL-Deficient and ACL-Intact Knees: A Matched Pair Analysis

BACKGROUND

Anterior cruciate ligament (ACL)-deficient knees are no longer considered a contra-indication for unicompartment knee arthroplasty (UKA). The purpose of this study was to determine if patients who had an ACL-deficient knee who underwent lateral UKA had similar mean 10-year outcomes compared to patients who had an ACL-intact knee and lateral UKA.

METHODS

Patients who underwent a lateral UKA with ACL deficiency by a single surgeon between 2004 and 2016 were identified. Preoperative magnetic resonance images were utilized to identify a torn or absent ACL in all knees. The absence of an ACL was confirmed during arthroscopy prior to UKA. Patients were matched 1:2 based on age and sex with patients who underwent lateral UKA with an ACL intact knee. The primary patient-reported outcome variable was survival without conversion to total knee arthroplasty. Secondary outcomes included Veterans Rand-12, the Lysholm score, the Knee Osteoarthritis Outcome Score activities of daily living subscale, and Sport subscale. A power analysis showed that 14 patients were needed to identify differences of 10 points on the Knee Osteoarthritis Outcome Score with a power of 80% (P = .05).

RESULTS

The cohort of patients who had an ACL-deficient lateral UKA included 4 men and 12 women (43 to 82 years of age). The matched control group included 32 patients. The mean age of both groups was 67 years (range, 43 to 85). There were 2 patients in the ACL-deficient group who failed. At 10 years, survivorship in the ACL-deficient group was 85%, while survival in the ACL-intact group was 100% (P = .035). At an average follow-up of 11 years (range, 4 to 19.6), there was no difference in outcome scores between ACL-deficient and ACL-intact patients.

CONCLUSION

Fixed-bearing lateral UKA in the ACL-deficient knee resulted in lower survival than patients who had an intact ACL. Patient-reported outcomes were similar in both groups. The ACL-deficient patient who wishes to undergo lateral UKA should be counseled on the lower survival.

LEVEL OF EVIDENCE

Level III. Retrospective cohort study.

Anterior cruciate ligament deficiency versus intactness for outcomes in patients after unicompartmental knee arthroplasty: a systematic review and meta-analysis

Objective: The unicondylar knee arthroplasty (UKA) procedure is primarily indicated for osteoarthritis of the knee. Anterior cruciate ligament (ACL) defects have long been considered a contraindication to UKA. However, recent clinical studies have found that ACL defects do not affect postoperative outcomes in UKA. To elucidate whether ACL defects affect postoperative outcomes in UKA, we performed a systematic review and Meta-analysis of observational cohort studies comparing the effects of ACL defects and intactness on surgical outcomes in UKA.

Methods: In this study, we used “Anterior Cruciate Ligament”, “Anterior Cruciate Ligament Injuries” and “Arthroplasty, Replacement, Knee” as the subject terms according to PICOS principles. These subject terms and the corresponding free texts were used to conduct a systematic search in the three major databases PubMed, Embase and Cochrane on December 9, 2021. The main study variables included age, gender, region, definition of ACL defect and diagnosed diseases. The study used a random effect model to pool the effect of 95% CIs. To explore the sources of heterogeneity and to test the stability of the results, a sensitivity analysis was performed.

Results: The systematic review found no significant differences in postoperative clinical outcomes in the elderly population when unicondylar replacement was performed in the setting of multiple factors such as injury, defects, longitudinal tear, and synovial bursa injury defined as ACL deficiency. The primary clinical outcomes included postoperative revision, Tegner activity score, and Oxford Knee Score (OKS). After statistical meta-analysis, postoperative outcomes such as postoperative revision (OR, 1.174; 95% CIs, 0.758–1.817) and Tegner activity score (OR, -0.084; 95% CIs, -0.320–0.151) were not statistically different.

Conclusion: There was no difference in postoperative revision rates and functional outcomes such as Tegner activity score between the ACL-deficient group compared with the ACL-intact group. For the present results, it is not advisable to consider ACL deficiency as a contraindication of UKA.

Computational analysis of tibial slope adjustment with fixed-bearing medial unicompartmental knee arthroplasty in ACL- and PCL-deficient models

AIMS

A functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different posterior tibial slopes.

METHODS

ACL- or PCL-deficient models with posterior tibial slopes of 1°, 3°, 5°, 7°, and 9° were developed and compared to intact models. The kinematics and contact stresses on the tibiofemoral joint were evaluated under gait cycle loading conditions.

RESULTS

Anterior translation increased in ACL-deficient UKA cases compared with intact models. In contrast, posterior translation increased in PCL-deficient UKA cases compared with intact models. As the posterior tibial slope increased, anterior translation of ACL-deficient UKA increased significantly in the stance phase, and posterior translation of PCL-deficient UKA increased significantly in the swing phase. Furthermore, as the posterior tibial slope increased, contact stress on the other compartment increased in cruciate ligament-deficient UKAs compared with intact UKAs.

CONCLUSION

Fixed-bearing medial UKA is a viable treatment option for patients with cruciate ligament deficiency, providing a less invasive procedure and allowing patient-specific kinematics to adjust posterior tibial slope. Patient selection is important, and while AP kinematics can be compensated for by posterior tibial slope adjustment, rotational stability is a prerequisite for this approach. ACL- or PCL-deficient UKA that adjusts the posterior tibial slope might be an alternative treatment option for a skilled surgeon. Cite this article: Bone Joint Res 2022;11(7):494-502.

Excellent outcomes with combined single stage Physica ZUK medial unicompartment knee replacement and anterior cruciate ligament reconstruction results in young, active patients with instability and osteoarthritis with a mean follow up of 5 years

BACKGROUND (INCLUDING THE AIM OF THE STUDY)

Young and more active patients with medial compartment osteoarthritis (OA) in conjunction with anterior cruciate ligament (ACL) deficiency are difficult to treat. The aim of this study was to explore the outcomes of combined fixed bearing Physica ZUK medial unicompartmental knee replacement (UKR) (Lima Corporate, Udine Italy) with ACL reconstruction for patients presenting with isolated medial compartment OA and symptomatic ACL deficiency.

METHODS

Patients who underwent simultaneous single stage ACL reconstruction and medial UKR between 2012 and 2020 by a single surgeon (GG) were included. Preoperative outcome measures including Lysholm, Tegner, Oxford Knee Score and VAS pain score were evaluated and were repeated postoperatively at the most recent follow up appointment.

RESULTS

Twenty four patients underwent simultaneous combined ACL and ZUK Medial UKR with a mean follow up of 5.1 years. Significant improvements in Lysholm (p < 0.001), Tegner (p < 0.001), Oxford Knee Score (p < 0.001) and VAS pain scores (p < 0.001) were seen with this combined approach with all patients returning to sport. Two patients had a minor peri-operative complication, which was treated conservatively. There were no revision procedures, and no evidence of implant loosening, however one patient had deceased due to an unrelated illness.

CONCLUSION

UKR combined with ACL reconstruction can be an effective treatment option for selected patients suffering from medial unicompartmental knee osteoarthritis and symptomatic ACL deficiency. This allowed active patients to return to sports, addressing both instability and OA pain in a specific patient population.

Patient-acceptable symptom state for reporting outcomes following unicompartmental knee arthroplasty : a matched pair analysis comparing UKA in ACL-deficient versus ACL-intact knees

AIMS

The patient-acceptable symptom state (PASS) is a level of wellbeing, which is measured by the patient. The aim of this study was to determine if the proportion of patients who achieved an acceptable level of function (PASS) after medial unicompartmental knee arthroplasty (UKA) was different based on the status of the anterior cruciate ligament (ACL) at the time of surgery.

METHODS

A total of 114 patients who underwent UKA for isolated medial osteoarthritis (OA) of the knee were included in the study. Their mean age was 65 years (SD 10). No patient underwent a bilateral procedure. Those who had undergone ACL reconstruction during the previous five years were excluded. The Knee injury Osteoarthritis Outcome Score Activities of Daily Living (KOOS ADL) function score was used as the primary outcome measure with a PASS of 87.5, as described for total knee arthroplasty (TKA). Patients completed all other KOOS subscales, Lysholm score, the Western Ontario and McMaster Universities Osteoarthritis Index, and the Veterans Rand 12-item health survey score. Failure was defined as conversion to TKA.

RESULTS

Survivorship at ten years was 97% in both the ACL-deficient and ACL-intact groups. The mean survival was 16.1 years (95% confidence interval (CI) 15.3 to 16.8) for the ACL-deficient group and 15.6 years (95% CI 14.8 to 16.361) for the ACL-intact group (p = 0.878). At a mean of nine years (SD 3.5) in the ACL-deficient group, 32 patients (87%) reached the PASS for the KOOS ADL. In the ACL-intact group, at a mean of 8.6 years (SD 3) follow-up, 63 patients (85%) reached PASS for the KOOS ADL. There was no significant difference in the percentage of patients who reached PASS for all KOOS subscales and Lysholm between the two groups.

CONCLUSION

PASS was achieved in 85% of all UKAs for KOOS ADL, similar to reports for TKA. Fixed-bearing, medial, non-robotically-assisted UKA resulted in 97% survival at ten years in both the ACL-deficient and ACL-intact groups. There was no significant difference in all outcomes between the two groups. Understanding PASS will allow better communication between surgeons and patients to improve the surgical management of patients with single compartment OA of the knee. This study provides mid- to long-term data supporting the use of PASS to document outcomes following UKA. PASS was met in more than 85% of patients with no differences between ACL-deficient and ACL-intact knees at a mean follow-up of nine years. Cite this article: Bone Joint J 2021;103-B(8):1367-1372.

Medial Osteoarthritis in an ACL-Deficient Knee: A Critical Analysis Review

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In anterior cruciate ligament (ACL)-deficient knees, treatment of medial compartment osteoarthritis (OA) that is refractory to nonoperative modalities is a controversial subject.

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Currently available treatment options include unicompartmental knee arthroplasty (UKA) with or without ACL reconstruction (ACLR), high tibial osteotomy (HTO) with or without ACLR, and total knee arthroplasty (TKA).

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Each treatment option has its own risks and benefits, and the evidence that is reviewed in this article suggests that patient characteristics guide treatment selection.

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Future high-quality prospective studies that directly compare all 3 of the modalities are necessary to determine the best treatment option for different patient populations.

Anterior cruciate ligament reconstruction combined to partial knee replacement in active patients with ACL deficiency and knee osteoarthritis

OBJECTIVES

To report, through a systematic review of the literature, the clinical and radiographic outcomes of unicompartmental knee replacement (UKR) combined to anterior cruciate ligament (ACL) reconstruction. It was hypothesized that this combined technique is a safe and effective procedure providing satisfactory post-operative functional outcomes.

METHODS

A systematic review was performed by searching Pubmed/MEDLINE, CINAHL, SCOPUS, Embase, and Ovid. Only studies in English pertaining all levels of evidence reporting on subjects with medial osteoarthritis and ACL deficiency undergoing UKR combined to ACL reconstruction were considered. Review articles and expert opinion or editorial pieces were excluded. Outcomes of interest included indications, clinical assessment including activity level, associated procedures, rate of complications such as revision surgery.

RESULTS

Overall, nine studies met all the inclusion criteria for this review. All were published between 2006 and 2019. The search resulted in one comparative case series (Level III), four prospective cohort studies (Level III) and four case series (Level IV). From these studies, 249 patients were identified.

CONCLUSIONS

The combination of UKR and ACL reconstruction appears a safe and effective procedure providing satisfying outcomes and limited complications in selected patients with medial OA and ACL insufficiency. Further comparative studies reporting long-term outcomes are needed, as high-level studies on this topic are lacking.

Medial unicompartmental knee arthroplasty to patients with a ligamentous deficiency can cause biomechanically poor outcomes

PURPOSE

The aims of this study were to investigate the biomechanical effects of the deficiency of the collateral ligament and cruciate ligament in medial unicompartmental knee arthroplasty in normal and varus knee patients using computational simulation.

METHODS

Validated finite-element (FE) models for conditions of various cruciate and collateral ligament deficiencies were developed to evaluate the biomechanical effects of ligamentous deficiency in UKA for normal and varus knee patients. Contact stresses on the polyethylene (PE) insert, contact stresses on the lateral articular cartilage, and quadriceps force were analyzed under gait-loading conditions.

RESULTS

Contact stresses on the PE insert and lateral articular cartilage as well as quadriceps force in a normal knee UKA FE model were increased in the order of anterior cruciate ligament (ACL) deficiency, medial collateral ligament (MCL) deficiency, lateral collateral ligament (LCL) deficiency, and posterior cruciate ligament (PCL) deficiency in the stance phase of gait cycle, as compared with those in the model without ligamentous deficiency. In two or more multiple ligamentous deficiencies, contact stresses on the PE insert and articular lateral cartilage and quadriceps force were significantly increased versus in the case of single-ligament deficiency.

CONCLUSION

Poor outcomes of medial UKA in patients with ACL or MCL deficiency can be predicted. Care should be taken to extend the indications when performing medial UKA in patients with ligamentous deficiency, especially when varus knee with ACL or MCL deficiency is present.

Excellent long-term results in combined high tibial osteotomy, anterior cruciate ligament reconstruction and chondral resurfacing in patients with severe osteoarthritis and varus alignment

PURPOSE

To determine survivorship and functional results of medial open-wedge high tibial osteotomy (HTO) combined with anterior cruciate ligament reconstruction (ACLR) and a chondral resurfacing (CR) procedure (abrasion/microfracture) in patients with Kellgren-Lawrence grade 3 and 4 osteoarthritis with full thickness-cartilage defects, ACL-insufficiency and varus alignment.

METHODS

A cohort of 23 patients undergoing a combined procedure of HTO (fixation with angular stable internal fixator, Tomofix^®), ACLR and CR for the treatment of severe symptomatic medial osteoarthritis, ACL insufficiency and varus alignment (> 4°) between 2005 and 2009 was prospectively surveyed with a minimum follow-up of 10 years with regard to survival (not requiring arthroplasty), functional outcome (subjective IKDC score), pain level (numeric rating scale), Oxford Knee Score (OKS) and subjective satisfaction. The Wilcoxon signed-rank-test was used for statistical evaluation of non-parametric data in these related samples.

RESULTS

Twenty-one cases were included, one case with incomplete follow-up data and another case excluded. The follow-up rate was 91% at 12.0 ± 1.0 years (10.0-13.4). Mean age at time of surgery was 47.3 ± 5.9 years (37.8-57.7). At final follow-up, no arthroplasty was performed in any of the cases (survival: 100%). Subjective IKDC score improved from 47 ± 11 to 75 ± 15 at 1, 72 ± 15 at 3, 73 ± 17 at 6 years and 70 ± 16 at final follow-up (p < 0.001), respectively. At final follow-up the OKS was 40 ± 7 (17-48) and pain-level significantly decreased from 7.5 ± 1.0 preoperatively to 2.9 ± 2.3 (p < 0.001) at final follow-up. All patients were satisfied with the result and stated that they would retrospectively undergo the procedure again.

CONCLUSION

A combined approach of HTO, ACLR and a CR shows excellent results in a long-term follow-up in selected young patients even in severe osteoarthritis. However, the role and potential benefit of the ACLR and CR compared to HTO alone remains unclear.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

[Research progress in unicompartmental knee arthroplasty]

OBJECTIVE

To summarize the clinical application and research progress in unicompartmental knee arthroplasty (UKA).

METHODS

The literature related to UKA in recent years was reviewed and the emerging indications, implant options, comparisons between other surgical techniques, and recent advances were summarized.

RESULTS

Clinical studies show that UKA has many advantages, such as less trauma, faster recovery, and fewer postoperative complications. At present, the operative indication has been expanded. The body mass index more than 25 kg/m 2, less than 60 years old, patellofemoral arthritis, and anterior cruciate ligament dysfunction are no longer considered as contraindications. The prosthesis type in UKA should be selected according to the patient's condition. In recent years, the robot-assisted UKA can effectively improve the effectiveness, improve patient satisfaction, and reduce postoperative complications.

CONCLUSION

With the development of surgical techniques, designs of prosthesis, and the robotic technology, UKA would be further applicated. As more long-term data on UKA become available, it will further guide clinicians in counseling patients on whether UKA should be performed.

Arthroscopy combined with unicondylar knee arthroplasty for treatment of isolated unicompartmental knee arthritis: A long-term comparison

BACKGROUND

Knee osteoarthritis is the most prevalent form of osteoarthritis and is becoming the main reason for progressive pain in knee joints. Arthroscopy combined with unicondylar knee arthroplasty (UKA) is one of the effective methods for the treatment of severe unicompartmental knee arthritis. This surgical approach gives us the capacity to explore all the articular cavities and plays a vital role in UKA patient selection. However, some scholars think that the surgical procedure is traumatic and may increase the rate of surgical infection, and its clinical efficacy needs further study.

AIM

To compare the clinical effect of arthroscopy combined with UKA and UKA alone for patients suffering from unicompartmental osteoarthritis (OA).

METHODS

A retrospective study was conducted on patients who were diagnosed with unicompartmental OA (Kellgren–Laurence grade ≥ III) and underwent UKA between October 2012 and November 2006. The patients were followed at 3, 6, and 12 mo and every 2 years thereafter. During each follow-up, the radiographic materials, the range of motion of knee and hospital for special surgery (HSS) score, knee society score and knee function score as recorded, and the modes and time of failure and revision details were collected as well.

RESULTS

Data on 104 patients (118 knees), including 54 patients (60 knees) in the arthroscopy combined with UKA group (group A) and 51 (58 knees) in UKA alone group (group B) were collected during an average follow-up duration of 7.25 years, excluding the cases who were lost to follow-up. At the final follow-up, 3 (5.0%) of 60 knees in group A compared with 4 (6.9%) of 58 knees in group B failed and converted to total knee arthroplasty, with no statistically significant difference between the two groups (P = 0.933). The percentage of patients receiving blood transfusion was 40% in group A, significantly lower than that in group B (67.2%; P = 0.003). Total volume of blood transfusion in group A was also significantly lower than that of group B (P = 0.001). Both groups improved significantly after operation in clinical symptoms and functions. HSS score, knee society score, and knee function score increased significantly at the latest follow-up compared to pre-operation in group A, from 59.6 ± 10.9 to 82.7 ± 9.3 (mean difference [MD], 23.2; 95%CI: 19.3-27.0; P = 0.000), 47.3 ± 6.3 to 76.2 ± 13.1 (MD, 28.9; 95%CI: 25.1-32.7; P = 0.000), and 57.5 ± 6.3 to 75.1 ± 19.6 (MD, 17.5; 95% CI: 12.1-23.0; P = 0.000); and in group B, from 59.3 ± 15.6 to 84.3 ± 10.1 (MD, 23.7; 95%CI: 18.9-28.5; P = 0.000), 49.1 ± 9.2 to 75.1 ± 13.2 (MD, 24.7; 95%CI: 19.9-29.5; P = 0.000), and 59.3 ± 9.0 to 77.4 ± 13.8 (MD, 17.2; 95%CI: 12.8-21.6; P = 0.000).

CONCLUSION

Arthroscopy combined with UKA and UKA alone both provide benefits in clinical symptom improvement and alignment correction. Arthroscopy combined with UKA does not increase the infection probability and surgical complications, and has an advantage in reducing the total volume of blood transfusion and the percentage of patients receiving blood transfusion.

Anterior cruciate ligament reconstruction in association with medial unicompartmental knee replacement: a retrospective study comparing clinical and radiological outcomes of two different implant design

PURPOSE

Unicompartmental knee arthroplasty (UKA) combined with anterior cruciate ligament (ACL) reconstruction has recently been suggested as a feasible treatment option for young and active patients with medial compartment osteoarthritis (OA) and ACL deficiency. The aim of this study is to evaluate retrospectively the outcomes of two different implant designs in patients with medial OA secondary to traumatic ACL rupture, who underwent combined ACL reconstruction and unicompartmental knee replacement.

METHODS

From January 2007, to December 2013, 24 patients with medial OA secondary to ACL rupture underwent medial unicompartmental knee arthroplasty (UKA) and ACL reconstruction. Nine patients received a mobile bearing UKA (Group 1) and fifteen a fixed-bearing one (Group 2). The mean follow-up was 53 ± 8.3 months for Group 1 and 42 ± 6.7 months for Group 2. Knee Society Score (KSS), Western Ontario and McMaster Index of Osteoarthritis (WOMAC) index and radiological evaluation used to assess the implant loosening alignment of the knee joint and tibial slope were recorded pre-operatively and at the last follow-up.

RESULTS

At the final follow-up, all patients showed statistically significant clinical improvements with respect to the pre-operative values (p < 0.05). No significant difference was observed in WOMAC index and KSS both objective and functional between groups at the last follow-up (KSS obj. 73.4 ± 9.3 vs 77.3 ± 10.5; KSS funct. 86.2 ± 6.2 vs 84.7 ± 5.9; WOMAC 79.3 ± 7.3 vs 81.3 ± 7.6 for Group 1 and 2, respectively). No differences in radiolucent lines were found between the groups.

CONCLUSION

The use of different prosthesis design (fixed- or mobile-bearing) during a combined procedure of ACL reconstruction and medial unicompartmental arthroplasty does not affect the middle-term clinical and radiological outcomes.

Outcomes of a Fixed-Bearing, Medial, Cemented Unicondylar Knee Arthroplasty Design: Survival Analysis and Functional Score of 460 Cases

BACKGROUND

Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty in isolated medial osteoarthritis (OA). However, despite satisfactory reports on the clinical performance, UKA revision rates are still concerning. This retrospective study reports on the long-term survivorship, functional outcomes, and reasons for revision in fixed-bearing UKA implant.

METHODS

Between 2005 and 2013, 460 consecutive patients were treated with medial UKA in one center using a fixed-bearing UKA system. All patients were evaluated clinically and radiographically before surgery, and postoperatively at 6 weeks and 1 year. Between February and April 2016, all patients were reevaluated using the Oxford Knee Score.

RESULTS

Mean follow-up was 5.5 (range, 2-11) years. The mean Oxford Knee Score was 43.3 (7-48), with 94.6% patients showing excellent or good outcomes. Eleven revisions (2.4%) occurred. The survivorship was 97.2% (95% confidence interval, 96.2%-99.2%) and 94.2% (95% confidence interval, 86.8%-97.5%) at 5 and 10 years, respectively, with revision of any implant component for any reason as the end point. The causes for revision were infection (4 cases, 0.9%); lateral pain due to overload (2 cases, 0.4%); progression of OA in the lateral compartment (2 cases, 0.4%); patellar pain with patellar chondropathy (2 cases, 0.4%); and severe synovitis (1 cases, 0.2%). There were no reoperations or revisions for component loosening, instability, component wear, or periprosthetic fracture.

CONCLUSION

A fixed-bearing UKA system is a good treatment option for medial end-stage OA. Satisfactory functional results were achieved with low incidence of complications and revisions.

Medial unicondylar knee arthroplasty combined to anterior cruciate ligament reconstruction

PURPOSE

The purpose of the present study was to retrospectively evaluate the outcomes of patients who underwent combined medial unicompartmental knee arthroplasty (UKA) and anterior cruciate ligament (ACL) reconstruction. The hypothesis was that this procedure would lead to a high success rate in patients affected by isolated medial unicompartmental osteoarthritis and concomitant ACL deficiency.

METHODS

Fourteen patients with primary ACL lesion and concomitant medial compartment symptomatic osteoarthritis treated from 2006 to 2010 were followed up for an average time of 26.7 months (SD 4.2). Assessment included KOOS score, Oxford Knee score, American Knee Society scores, WOMAC index of osteoarthritis, Tegner activity level and objective examination including instrumented laxity test with KT-1000 arthrometer. Radiological assessment was done with standard simple radiographs in order to get information about any presence of loosening of the components.

RESULTS

KOOS score, OKS, WOMAC index and the AKSS improved significantly after surgery (p < 0.001). Regarding AKSS, improvement was noted both in the objective score and in the functional one (p < 0.001). There was no clinical evidence of instability in any of the knees as evaluated with clinical laxity testing. No pathologic radiolucent lines were observed around the components. In one patient signs of osteoarthritis in the lateral compartment were observed 28 months after surgery.

CONCLUSIONS

UKA combined with ACL reconstruction is a valid therapeutic option for the treatment of combined medial unicompartmental knee osteoarthritis and ACL deficiency in young and active patients and confirms subjective and objective clinical improvement 2 years after surgery. The use of a fixed-bearing prosthesis represents a reliable feature as it allows to overcome problems of improper ligament tensioning during the implantation of the components.

LEVEL OF EVIDENCE

IV.

The Role of Preoperative Patient Characteristics on Outcomes of Unicompartmental Knee Arthroplasty: A Meta-Analysis Critique

BACKGROUND

In 1989, Kozinn and Scott introduced strict exclusion criteria for unicompartmental knee arthroplasty (UKA). Because outcomes have improved with modern techniques and implants, these criteria have now been challenged. Therefore, the goal was to assess the role of these criteria on (1) functional outcomes and (2) revision rates of medial UKA. The hypothesis was that, with modern surgical techniques and implants, these traditional exclusion criteria are no longer strict contraindications for UKA.

METHODS

Databases of PubMed, EMBASE, and Cochrane and annual registries were searched for studies comparing UKA results in subgroups: age (young vs old), gender (male vs female), body mass index (obese vs nonobese), present vs absent patellofemoral osteoarthritis, and intact vs deficient anterior cruciate ligament.

RESULTS

Thirty-one comparative cohort studies (7 level II and 24 level III/IV studies) and 6 registries reported outcomes in 17,147 patients and revision rates in 285,472 patients. Females had inferior functional outcomes compared to males (odds ratio [OR], 4.03; 95% CI, 1.77-6.30). Furthermore, younger patients (in studies: OR, 1.52; 95% CI, 1.06-2.19; in registries: OR, 2.09; 95% CI, 1.70-2.57) and females (OR, 1.13; 95% CI, 1.06-1.21) had increased likelihood for revision. No increased likelihood for inferior outcomes or revisions was detected in patients with obesity, preoperative patellofemoral osteoarthritis, or anterior cruciate ligament deficiency.

CONCLUSION

Findings of increased revision risk in younger patients and increased revision risk with inferior outcomes in females give a more nuanced perspective on historical criteria, such that surgical decision-making may be based on UKA outcome data for subgroups rather than strict exclusion criteria.

No difference between unicompartmental versus total knee arthroplasty for the management of medial osteoarthtritis of the knee in the same patient: a systematic review and pooling data analysis

INTRODUCTION

One-third of patients with knee osteoarthritis (OA) has involvement of only one compartment, especially the medial one.

SOURCES OF DATA

We performed a comprehensive search of studies comparing unicompartmental knee arthoplasty (UKA) and total knee arthroplasty (TKA) in the same patient on PubMed, OVID/Medline, Cochrane, CINAHL, Google scholar and Embase databases.

AREAS OF AGREEMENT

UKA is indicated in knee with medial OA, no flexion deformity, no joint instability and no varus deformity.

AREAS OF CONTROVERSY

Although high tibial osteotomy, UKA and TKA have been proposed to address medial OA of the knee, the best management is still controversial.

GROWING POINTS

Studies investigating surgical management of medial OA of the knee are increasingly frequent.

AREAS TIMELY FOR DEVELOPING RESEARCH

Large, multicentre, powered, randomized trials comparing UKA and TKA are needed to identify the best management for medial OA of the knee. Moreover, new score systems for satisfaction of the patient should be formulated.