At a minimum 12 years follow-up the Authors performed a matched paired study between 2 groups: Bi-Unicompartimental (femoro-tibial) versus Total Knee Replacements, both navigated, they hypothesised that Bi-UKR guarantees a clinical score and patient satisfaction at least similar to TKR without differences in survivorship. 19 BI-UKR (1999–2003) were included in the study (group A). Every single patients in group A was matched to a computer-assisted TKR implanted in the same period (group B). The clinical outcome was evaluated using the Knee Society Score, the GIUM Score and the WOMAC Arthritis Index. Radiographically the HKA angle and the Frontal Tibial Component angle (FTC) were. Statistical analysis of the results was performed and Kaplan-Meir survival rate was assessed in both the groups.Introduction
Materials and Methods
The purpose of this study is to investigate whether traditional morphometric parameters of the femur trochlear surface are dependable to classify the severity of the trochlear dysplasia. An automatic method to process the distal femur surface is proposed to determine anatomical landmarks and compute morphometric parameters, namely the trochlear depth(TD), the trochlear sulcus angle(SA), the lateral trochlear facet inclination(LFTI), the trochlear facet asymmetry ratio(TFAR) and the ratio between the two (lateral and medial) maximum antero-posterior sizes(CAR) routinately used to quantify trochlear dysplasia. Tests on 11 cadavers and 43 patients, affected by aspecific anterior knee pain, elucidate the role of the parameter cut-off values traditionally used in clinical practice.Purpose
Methods
Aim of this study is to assess any differences in digital templanting accuracy of a modular short femoral stems implanted with 2 different appoaches (direct anterior and posterolateral). From December 2012 to Jenaury 2014 100 patient undergoing to a THA using the same implant with a short femoral modular stem were prospectively included in the study and divided in 2 groups according to the surgical approach. All the patients underwent to the same preoperative radiological protocol and the digital templating. The digital templating results were compared with the truly inserted implant size and a statistical analysis was carried on.Introduction
Material and Methods
Aim of the study was to assess difficulties and adverse effects in more than 400 CAS hip replacements using a short modular femoral stem to assess their incidence and to determine if this surgical procedure has to be considered as an high demanding surgical technique. Since 1998, 511 computer assisted hip replacements using a short modular stem were performed in our department. 403 implants were followed for at least 6 months postoperatively and included in the study. All the cases were divided into 3 series according to when the surgery had been performed to consider the evolution of the navigation systems and the surgeons familiarity with this improvement (group A: 1998–2003, group B: 2004–2008 and group C: 2009–2014). All intra-operative problems (difficulties that required no operative intervention to resolve or without any conseguence on the navigation process), intra-operative obstacles (difficulties that required operative intervention or that caused a failure of the navigation process) and complications (intra-operative injuries and all the problems following in the first 6 months post-operatively) were registered. Adverse facts not directly caused by the surgical but derived by other conditions were excluded from the study.Purpose
Materials and Methods
The purpose of this study was to compare the results and complications of tibial lengthening over an intramedullary nail with treatment using the traditional Ilizarov method. In this matched case study, 16 adult patients underwent 19 tibial lengthening over nails (LON) procedures. For the matched case group, 17 patients who underwent 19 Ilizarov tibial lengthenings were retrospectively matched to the LON group.Objectives
Methods
Despite clear clinical advantages Unicompartimetal Knee Replacement still remain an high demanding and less forgiving surgical procedure. Different Authors in literature pointed out how malalignment increases the rate of aseptic failure even more than in TKR. Computer-assisted surgery has been proposed to improve implant positioning in joint replacement surgery with no need of intramedullary guide despite no still proven clinical advantages. Likewise more recently Patient Specific Instrumentation (PSI) has been suggested, even in partial knee reconstruction, as a new technology capable of new advantages such as shorter surgical times and lower blood losses maintaining at least the same accuracy. Aim of the study is to present a prospective study comparing 2 groups of UKR s using either a computer assisted technique or a CT-based Patient Specific Instrumentation. Since January 2010, 54 patients undergoing UKR because medial compartment arthritis were enrolled in the study prospectively. Before surgery patients were alternatively assigned to either computer-assisted alignment (group A) or patient specific instrumentation group (group B). In the group A (27 knees) the implant (Sigma, Depuy Orthopaedics Inc, Warsaw, Indiana, USA) was positioned using a CT-free computer assisted alignment system specifically created for UKR surgery (OrthoKey, Delaware, USA). In group B (27 knees) the implant (GMK Uni, Medacta, Castel San Pietro, Switzerland) was performed using a CT-based PSI technology (MyKnee, Medacta, Castel San Pietro, Switzerland). In both the groups all the implants were cemented and using always a fixed metal backed tibial component. The surgical time and complications were documented in all cases. Six months post-operatively the patients underwent to the same radiological investigation to determine the frontal femoral component angle (FFC), the frontal tibial component angle (FTC), the hip-knee-ankle angle (HKA) and the sagittal orientation (slope) of tibial/femoral components. The number and percentage of outliners for each parameter was determined. In addition the percentage of patients in each group with all 5 parameters within the desired range was calculated. Furthermore the 2 groups were clinically assessed using KSS and Functional scoreINTRODUCTION:
MATERIALS AND METHODS:
Despite clear clinical advantages Unicompartimetal Knee Replacement (UKR) still remain a high demanding and less forgiving surgical procedure. Different Authors in literature pointed out how in coronal tibial malalignment beyond 3° as well as tibial slope beyond 7° increase the rate of aseptic failure. Likewise, overcorrection in the coronal plain is a well recognised cause of failure because of an overweighting on the controlateral compartment. Furthermore it has been shown how in UKR surgery even using short narrow intramedullary guide this can cause errors in both coronal planes. Computer assisted surgery has been proposed to improve implant positioning in joint replacement surgery with no need of intramedullary guide. Likewise more recently Patient Specific Instrumentation (PSI) has been suggested as a new technology capable of new advantages such as shorter surgical times and lower blood losses maintaining at least the same accuracy. Aim of this prospective study is to present comparing 2 groups of UKRs using either a computer assisted technique or a CT based PSI. Since January 2010 54 patients undergoing UKR because of medial compartment arthritis were prospectively enrolled in the study. Before surgery patients were alternatively assigned to either computer-assisted alignment (group A) or PSI group (group B). In the group A (27 knees) the implant (Sigma, Depuy Orthopaedics Inc, Warsaw, Indiana, USA) was positioned using a CT-free computer assisted alignment system specifically created for UKR surgery (OrthoKey, Delaware, USA USA). In group B (27knees) the implant (GMK uni, Medacta, Castel San Pietro, Switzerland) was performed using a CT-Based PSI technology (MyKnee, Medacta, Castel San Pietro, Switzerland). In both the groups all the implants were cemented and using always a fixed metal backed tibial component. The duration of surgery and all the complications according to Kim classification were documented in all cases. Six months after surgery each patient had long-leg standing anterior-posterior radiographs and lateral radiographs of the knee. The radiographs were assessed to determine the Frontal Femoral Component angle (FFC), the Frontal Tibial Component angle (FTC), the Hip-Knee-Ankle angle (HKA) and the sagittal orientation (slope) of both tibial and femoral component. The number and percentage of outliners for each parameter was determined. In addition the percentage of patients from each group with all 5 parameters within the desired range was calculated. Furthermore at the latest follow-up the 2 groups were clinically assessed using KSS and Functional score.INTRODUCTION
MATERIALS AND METHODS
A preoperative planning for accurately predicting the size and alignment of the prosthetic components may allow to perform a precise, efficient and reproducible total knee replacement. The planning can be carried out using as a support digital radiographic images or CT images with three-dimensional reconstruction. Aim of this prospective study is to evaluate and compare the accuracy of two different types of pre-operative planning, in determining the size of the femoral and tibial component in total knee arthroplasty performed with Patient Specific Instrument (PSI). The two compared techniques were: digital radiography and “CT-Based”. A prospective study was conducted to compare the accuracy in predicting the size of the prosthetic components in total knee replacement in 71 patients diagnosed with primary and symptomatic osteoarthritis of the knee. Inclusion criteria was “Easy Knee”: BMI ≤ 35, varus/valgus deviation ≤15° and residual flexion of the knee ≥ 90°. Pre-operatively all the patients underwent to the same standard protocol including digital radiographs with calibration and a CT scan. A dedicated IMPAX digital software (Agfa-Gevaert, NV, USA) was used to template the radiographs. The CT-based planning was performed on 3D reconstruction of CT scans of 3 joints: hip, knee and ankle, as established in standardised protocol to build up patient specific cutting mask (MyKnee, Medacta, Castel S. Pietro, Switzerland). All the surgeries were performed by 2 senior Authors (M.A and N.C.) using the same implant and the definitive component sizes implanted were registered and compared with the sizes suggested by both planning techniques considering also the range of error. Results analysis was carried out using nonparametric tests.INTRODUCTION
MATERIALS AND METHODS
The authors performed a short term prospective study of unicompartmental knee replacement (UKR) associated to patella-femoral arthroplasty (PFA) for the treatment of bicompartmental symptomatic knee arthritis. At the latest follow-up all the implants were matched to a similar computer assisted Total Knee Replacements (CAS-TKR) group implanted for the same indications. Hypothesis of the study was that this bicompartimental implants could achieve comparable outcomes to TKR with a more conservative surgery and a higher joint function. 19 cases of anteriomedial (12) or anterolateral (7) arthritis in 19 stable knees were prospectively involved in the study. All the knees underwent to a selective reconstruction using simultaneously both UKR and PFR using the same surgical technique. All bicompartmental implants were performed by the same surgeon. Surgical time, hospital staying and all intra and post operative complications were registered. At a minimum follow-up of 20 months, every single case was marched to a similar case where had been implanted a computer assisted cruciate retaining TKR. Criteria of matching were: sex, age, pre-operative range of motion and arthritis grade. In both the groups all the cases were assessed clinically using WOMAC, KKS and GIUM scores. All the knees were radiologically investigated using the same radiological protocol.Introduction
Materials and Methods
Post traumatic arthritis of the knee can be a conseguence of distal femur fracture and retained hardware can complicate any further surgical option including arthroplasty. Both staged surgical procedures to remove before the hardware or simultaneous procedure of arthroplasty and removal of hardware have been indicated with an increased risk of complications. Aim of this study is to present a consecutive series of TKA following distal femur fracture using a computer assisted technique without the removal of retained hardware assessing both the efficacy of navigation in managing these complex cases as “routinary” primary arthroplasties. A consecutive series of 16 patients treated with a computer assisted TKR following femoral fracture and with retained hardware were included in the study (group A). The interval between the fracture and operation averaged 5.8 years (range 1–12 years), the retained hardwares was an intramedullary nail in 6 cases, distal lateral plates in 7 cases and screws in 4 cases. All patients in group A were matched with a patient who had undergone to a computer assisted TKR using the same implant and software because of atraumatic knee arthritis in the same period (group B). Patients were matched in terms of age, gender, pre-operative range of motion, pre-operative arthritis severity according to Albaack classification, type and grade of deformity and implant features (cruciate retaining or sacrificing). There were 10 male and 6 female for each group, the mean pre-operative age was 64.3 years (range: 54–72) for the group A and 65.4 years (range: 53–74) for the group B. The mean pre-operative flexion was 85.5 degrees (range: 65–115) and 88.1 degrees (range: 70–115) for the post traumatic group and the matched group respectively.Introduction
Material and Methods
The Authors performed a matched paired study between 2 groups UKR or CA-TKR implanted with a mini-incision (MICA group) in the treatment of isolated medial compartment knee arthritis. The Authors hypothesized that UKR offers a real less invasive surgery with lower economical costs despite a worse limb/implant alignment. Furthermore at a minimum 40 months follow-up they hypothesized that this small implant guarantees still both better clinical score and patient satisfaction than in the MICA group. Thirty two patients with isolated medial compartment knee arthritis who underwent to a medial UKR from February 2001 to September 2002 were included in the study (UKR group). In all 32 knees the arthritic change was graded according to the classification of Älback 1. Arthritic change did not exceed grade IV in the medial compartment and grade II in the patello-femoral compartment. All patients had an asymptomatic patello-femoral joint. All patients had a varus deformity lower than 8° and a body mass index lower than 30. No patient had any clinical evidence of ACL laxity or flexion deformity and all had a preoperative range of motion of a least 110°. At a minimum follow-up of 48 months, every single patients in group A was matched with a patient who had undergone a computer assisted TKR performed with a less invasive approach (shorter than 12 cm) for an isolated medial compartment knee arthritis between August 1999 and September 2002 (MICA group) in our hospital. At latest follow-up the clinical outcome was evaluated using both the Knee Society Score and a dedicated UKR score developed by the Italian Orthopaedic UKR Users Group (GIUM). The HKA angle and the Frontal Tibial Component angle (FTC) were measured at latest follow up on long leg standing anterior-posterior radiographs and the mean values between the 2 surgeons assessments were used as final values. Furthermore during the hospital staying we registered in both the groups when each patient was standing comfortably in full weight-bearing according to a self- answered questionnaire and the data were compared. Statistical analysis of the results was performed using parametric test (Student’s t-test). A statistical comparison of the percentage of results for the GIUM score was performed using the Chi-square test. A statistically significant result was given a p≤ 0.05. Both hospital stay and operative time were statistically longer obviously in MICA group. In the UKR group the mean surgical time was 51.5 minutes (range: 36–75) (p<
0.001) while in the MICA group was 108.8 minutes (range: 80–132) (p<
0.001). In the UKR group the patients remained in the hospital for a mean of 5.1 days (range: 3–7) and in the MICA group 8.2 days (range: 4–16). At the latest follow-up the mean Knee Society Score was 80.5 (range: 70–100) and 78.4 (range: 70–87) for group A and B respectively. No statistically significant difference was seen for the Knee Society score between the 2 groups (p=0.08). The mean Functional score was 83.5 (range: 73–100) for group A and 78.8 (range: 59–90) for group B. A statistically significant difference was seen for the Functional score with superior results for group A (p=0.02). A statistically significant difference was seen for the GIUM score with better results for group A (p=0.01). The mean GIUM score was 76 (range: 67–90) and 73.02 (mean: 65–85) for group A and B respectively. At latest follow up the mean HKA angle was 176.8° for group A (range: 174°–182°) and 179.3° for group B (range 177–182) (p<
0.001). The mean FTC angle was 86.9° (range: 84°–90°) and 89.4° (range: 87°–92°) for group A and B respectively (p<
0.001). All TKR implants were positioned within 4 degrees of a HKA angle of 180° and FTC angle of 90°. At the latest follow-up (minimum 48 months) no statistically significant difference was seen in the postoperative Knee Society score for either group. However, significant differences were seen between the 2 groups in the functional results and in the GIUM score with better results in the UKR group. All the patients achieved a range of motion greater than 120° and could walk for longer distances. During the hospital staying in this group the patients reported a statistically significant earlier full weight-bearing. This was despite a significant less accurate limb alignment. In addition to inferior results for the computer assisted mini-invasive TKR group the costs of the procedure were obviously greater because of the expensive implants and technology along with statistically significant longer surgical times and hospital stay
Patients were randomly assigned to either the traditional or computer-assisted alignment group opening a closed envelope just prior to the skin incision. In the MIS group (37 knees) a minimally invasive approach was performed using an intramedullary femoral guide and an extramedullary tibial guide. In the MICA group (37 knees) the implant was positioned using a CT-free computer assisted alignment system (Vector Vision, version 1.52, BrianLAB, Munich, Germany) using the same minimally invasive surgical approach (mini-parapatellar). The duration of surgery was documented in all cases. Eight months after surgery each patient had long-leg standing anterior-posterior radiographs and lateral radiographs of the knee. All the radiographs were always taken with a standardized protocol with the same magnification. The radiographs were assessed by an independent radiologist blinded to the original procedure to determine the frontal femoral component angle (FFC), the frontal tibial component angle (FTC), the hip-knee-ankle angle (HKA) and the sagittal orientation (slope) of both femoral and tibial components. The number and percentage of outliners for each parameter was determined. In addition the percentage of patients from each group with all 5 parameters within the desired range was calculated.
The alignment of the femoral component as determined by the slope was significantly better in the MICA group (p<
0.001). Comparison of the FTC angle showed a statistically better alignment in the MICA group (p<
0.029). There were no statistical significant differences in HKA, FFC angles and in the slope of the tibial component between the 2 groups. All the implants in the MICA group achieved HKA and FTC angles aligned within this range while only 31 implants (83.8%) in the MIS group achieved similar accuracy. These differences in HKA and FTC angles were statistically significant (p=0.025). Thirty-six (97.3%) implants in the MICA group achieved a femoral slope aligned within 3 degrees of the desired position compared with 31 (83.8%) implants in the MIS group. In the MICA group 36 implants (97.3%) achieved a tibial slope aligned within this range while in the MIS group 33 implant (86.5%) achieved a similar result. A FFC angle aligned within 3 degrees of the desired position was achieved in 35 (94.6%) and 32 (86.5%) of the implants in the MICA and MIS groups respectively. These differences in femoral and tibial slope and FFC angle were not statistically significant. A statistically significant difference (p<
0.001) in the total number of outliners was seen with 158 and 181 in the MICA and MIS groups respectively. The number of implants with all 5 radiological parameters aligned within the desired range was statistically higher in the MICA group (p=0.001). Thirty-three implants (89.2%) in the MICA group and 20 (54.1%) in the MIS group were correctly aligned in all measured parameters.
However recently, after initial enthusiasm, authors have recommended caution when using mini-invasive techniques for total joint replacement. Computer-assisted surgery has the potential to address the difficulties of correct component positioning and alignment in minimally invasive knee replacement. Recently a prospective randomised study comparing computer navigation assisted minimally invasive TKR to conventional TKR reported a lower incidence of radiological outliners and better pain score in the computer navigation group. In this prospective randomized the comparison of the radiological results showed statistically significant differences between the 2 groups for component positioning both in the coronal plane and sagittal plane. The desired femoral slope and FTC angle were achieved in significantly more patients in the MICA group than the MIS group. Furthermore the results supported previous studies showing a statistically significant reduction in the number of outliners in the computer-assisted technique. In addition, the number of implants with all parameters aligned within desired values was statistically higher in the MICA group. No complications were seen in either group however the surgical time was statistically longer in the MICA group. Longer follow-up will be needed to demonstrate any correlation between the lower numbers of outliners and superior clinical outcome and implant survivorship in the computer navigation group.
Nowadays unicompartimental knee replacement (UKR) is a valuable solution for the treatment of knee osteoarthritis. Likewise in selected cases bicompartimental arthritis of the knee in patient younger than sixty still remains a challenge for the orthopaedic surgeon. In this selected cases, the Authors present their experience in performing a mini-invasive bi-unicompartimental knee replacement assisted by a computer navigation system trying to obtain both a correct alignment and a soft tissue balancing. From January to December 2003, the Authors treated 5 patients (5 knees) with bicompartimental arthritis of the knee. The mean age was 66 and in all the cases there was a arthritis deformity with intact both ACL and PCL without any pain at the femur-patella joint. All the patients had previously undergone to multiple surgical procedures. Orhophilot (4.0 version) navigation system (Aesculap, Tuttlingen, Germany) was used during the surgery to assist prosthesis placement. In all the cases a minimal surgical approach was used (7 to 9 cm skin cut). The patients were assessed using a UKR dedicated outcome score, Italian UKR User’s Group (G.I.U.M.) score, pre-operatively and at the latest follow-up. Pre-operatively the mean GIUM score was 49.1 (range 26–63) At the lastest follow-up the mean GIUM score was 80.2 (range :75–94). The average femoral-tibial angle was 179° (range 177° −181°). All the patients had a good ligament balancing with computer assisted spreader device. All the patients were satisfied and had returned to their previous occupation soon. According to their previous experience performing bi-unicompartimental prosthesis, the Authors underline how the computer navigation system support ligaments balancing and a correct prostheses alignment. They emphasize this real mini-invasive surgical approach to the cure of the knee arthritis, above all in young patients with post traumatic deformities.
Drainage of the surgical wound following major surgical procedures is advocated to avoid haematoma formation. Recently the need for of wound drainage in joint arthroplasty has been questioned. The aim of this prospective randomised study is to determine the benefits of a postoperative closed-suction drain after UKR. In a prospective randomised trial we evaluated the use of a postoperative closed-suction drain in unicompartmental knee replacement. Seventy-eight patients were divided into two groups: one without a postoperative closed-suction drain (Group A) and one with a drain (Group B). Both groups were matched for age, sex, and pre-operative haemoglobin. In group A we observed a lower day one post-operative analgesic requirement, smaller knee circumference 3 days postoperatively and less local wound complications. No deep infections occurred in either group during the follow-up period. Drain usage in UKR resulted in no significant advantage in postoperative pain, range of motion, and hospital stay. Post-operative drainage does however increase the cost of the procedure both in labour and equipment expenditure. We conclude that avoiding postoperative closed-suction drainage in UKR does not influence the final outcome.
As total knee arthroplasties (TKA) have become the gold standard procedure for severe gonarthrosis, greater interest in postperative tibiofemoral instability has developed. Emphasizing the correlation between evaluation of symptoms and findings, offers an opportunity to elucidate the specifics of the instability. Mandatory is the joint gap measurement during surgery to assess the effect of specific cuts or releases of the anatomic portion of the joint gap. By performing navigation-assisted total knee arthroplasties, we are capable of measuring the joint gap in a highly reliable way. During the ligament balancing in navigation-assisted TKA, we performed a data collection of the joint gap in 0–30 and 90 of flexion in 100 patients. The measurements were repeated after 10 and 20 minutes in extension. The result offers us an opportunity to assess the interesting effect of ligament-stress relaxation in TKA and to gain more insights in the further release-necessity and choice of insert during the TKA procedure.
Malalignment in total knee replacement (TKR) is frequently associated with early failure and poor functional results. It has been suggested that errors in tibial and femoral alignment of >
3° occurs in at least 10% of TKR. Since 1999 we have been using a computer-based alignment system (Orthopilot;Aesculap,Tuttlingen,Germany) for TKR in more than 300 implants. The aim of this retrospective study is to present our experience in comparison with traditional alignment systems for TKR. Patients receiving TKR with different alignment systems were enrolled in the study and assigned to three different groups. In group A (38 cases) TKR was performed using a computer-assisted alignment system, in group B (40 cases) TKR was performed using a totally intramedullary alignment system and in group C (37 cases) TKR was performed using a totally extramedullary alignment system. The criteria for inclusion were a diagnosis of primary osteoarthritis, a pre-operative mechanical frontal axis (MFA) ranging from 165° to 195°, and a pre-operative knee flexion deformity not exceeding 10° calculated according to pre-operative radiographs. The radiographs were assessed for the alignment of the femoral and tibial component and the lower limb alignment, considering the lateral femoral component angle (FCA), the medial tibial component angle (TCA), respectively. The surgical time was statistically longer in the computer-assisted group. The results did not show statistically significant differences in FCA, TCA and MFA among the three groups. However, in the extramedullary aligned group there was a statistically higher percentage of TKRs with both an abnormal FCA and MFA compared to the computer-based alignment group. Furthermore, in the computer-based alignment group all the implants were aligned within 4° of an ideal MFA. Our results demonstrate the significant improvement in the accuracy of implant alignment using a computer-assisted system compared to an extramedullary one. Furthermore, we underline how stressing the knee during all the phases of the registration process for the navigated implant can demonstrate how much of the deformity can be corrected and thus guide the soft-tissue release.
Unicompartmental knee arthroplasty (UKA) surgery has had a troubled history. In the late 1970s high failure rates and the success of bicondylar knee replacement made UKA less popular. Failures were mainly caused by improper implant design, incorrect patient selection and inadequate instrumentation. In the last few years the advent of guiding systems for more accurate alignment, new implant design and better patient selection have improved results and renewed interest in UKA. We present a retrospective study of two consecutive series of 60 cases of UC-PLUS SOLUTION UKA and 60 cases of SEARCH AESCULAP computer-assisted total knee arthroplasty (TKA) using ORTHOPILOT software navigation, performed between September 1999 and September 2001. The patients, 45 men and 75 women, had a mean age of 69.5 years (47–85) and the two groups were comparable in terms of age, sex, size, weight (60–85 kg), aetiology, pre-operative range of motion (mean flexion: 100°; range: 90°–140°), pre-operative IKS score, mechanical axis and Alhlback radiographic degrees. The mean femoral-tibial angle was 175° (range:167°–195°). All the operations were performed by the same surgeon. Aim of the surgical procedure was to obtain an ideal femoral-tibial angle of 180°, relieve the pain and restore a better range of motion. The results showed an excellent alignment of the limbs with the computer-assisted system, but a better IKS score in the UKA group as regards range of motion, pain and walking.
Nowdays bicompartmental arthritis of the knee in patients younger than 60 still remains a challenge for the orthopaedic surgeon. In these selected cases, the authors present their experience in performing a minimally invasive bi-unicompartmental knee replacement assisted by computer navigation. From January to December 2003, the authors treated seven patients (seven knees) with bicompartmental arthritis of the knee. The mean age was 66 and in all the cases an arthritis deformity was present but with no ligament deficiency and a pain-free femur-patella joint. The Orhophilot (4.0 version) navigation system was used during the surgery to assist prosthesis placement. In all the cases a minimally invasive surgical approach was used (7- to 9-cm skin incision). The patients were assessed using a UKR dedicated outcome score (GIUM Score), pre-operatively and at the latest follow-up. Pre-operatively the mean GIUM score was 49.1 (range 26–63) At the lastest follow-up the mean GIUM score was 80.2 (range :75–94). The average femoral-tibial angle was 179° (range 177°–181°). In all the cases a good ligament balancing was achieved using a computer-assisted spreader device. All the patients were satisfied and had returned to their previous occupation soon. The authors underline how the computer navigation system supports ligament balancing and correct prosthesis alignment. They did not register any fracture of the tibial intercondylar eminence because of wrong balancing and incisions. They emphasise this truly minimally invasive surgical approach to the cure of knee arthritis, above all in young patients with post-traumatic deformities.
